| Author | Message | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 1 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
discovered this site a month ago,it is simply amazing,i've learned so much already. i am buying either a gm1964 detroit 4106 155000 miles and 35ft it looks in pretty good shape,not much smoke at startup my uncle is asking $5000 inside is already converted to my needs or my friends father has a 40ft gm4107 with 450000miles and asks $6000 for it,the bus smokes very very heavily(white smoke)at startup and smokes a bit while driving(even after 200 miles) a mechanic claims after only hearing the engine that it is either bad injectors or a bend rod. also this one is already converted to my satisfaction and this one looks ok on the outside. i have not much money to spend now but will have some more cash flow in a few months. what do you think and what do you recommend me doing before i pay and drive 1000 miles home. i'm planning on bringing it to a shop here in austin for a mayor tune up and have all fluids changed. thanks 4 | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 715 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
the 4107 is 35 too.. & it sounds like an expencive overhaul is in it's future,can't imagine why you would consider it...all diesels smoke on start-up,NONE of them are happy till they get to 180..the two cycle is especially sensative to cold & my thoughts are it should never be started below 30 without a warm-up from a block heater,I guess there are times when this is not possible,I'd definitly buy the one that runs good,I'm not too far from you, I'm in Harlingen | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 2 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
he bob yeah other busdrivers i know also tell me to stay away from that 4107 and the guy told me it is 40ft,and a bend rod is a red flag to anybody i mwntioned it to. the gm4106 sounds great with not much smoke at all for a 1964 bus. so i guess i go with the 4106,does the price seem reasonable(5k)or am i 100% sure doomed for an overhaul even if it has only 155000 miles. off course i'm expecting "minor" repairs since i'm planning on traveling 7 months with it this year | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 93 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
Evening Dutch, Before morning, several people will tell you to take the prospective coach of your choice to a COMPETENT bus mechanic for a thorough exam BEFORE you buy. Please follow their (and my) advice and do so. A 4107 is 35 feet long, and is known as a buffalo, for obvious reasons, after looking at a side view. If the second coach you are talking about IS 40 feet, then it is a 4903, or 4905, just a longer buffalo. Unless these two coaches were bought as shells and converted new, I would add at least 750,000 miles to the 4106, and 500,000 to the other. There are other very well informed members here who can tell you who the original owner of both of these buses was, just by the serial numbers. Post 'em and watch! Look closely at the tires, look for a spare. See if you can find out when the hoses were changed last. Buses have a defroster core in the nose, the main heater is underneath, be certain that the driver's heater/defroster works/heats before you attempt to drive 1000 miles in a new to you vehicle! HTH George | ||
| Laryn Christley (Barn_owl)
Registered Member Username: Barn_owl Post Number: 4 Registered: 10-2006 Posted From: 71.254.45.168 Rating: N/A |
Dutch, If it is the bus in Virginia that I think it is, the owner has said that “The mileage listed is only an estimate because the old mechanical odometer has never worked since we acquired it about 12 years ago.” With that being said, mileage doesn’t mean much with a bus; it’s how well it has been maintained. They can be repaired and rebuilt time after time. The 4106 is a great bus, I own one, and my father owns two. Good luck. | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 112 Registered: 10-2004 Posted From: 71.59.75.212 Rating: N/A |
Not all Diesels Smoke on Startup Not all DD's Leak Oil at least 750,000 to the 06..... My 04 had over 2.5 million miles on it when we got it in 1978 and thats just from the records of the first operator. | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 3 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
he laryn you know about a bus in virginia??? any info on that one?? both busses i had in mind are in oklahoma.anyway im just worried with the traveling that im planning that i need a decent bus and hope the 4106 will do it also what do you guys think of pressure washing the engine(like at a blue beacon washplace) and can i fill an old 1964 bus up with flying j diesel???? thanks for all the help | ||
| Douglas Wotring (Tekebird)
Registered Member Username: Tekebird Post Number: 113 Registered: 10-2004 Posted From: 71.59.75.212 Rating: N/A |
washing enngine no real problem. Fuel......anyplace that sells diesel....I prefer Flying J myself | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 4 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
douglas you fill up at the rv island or the trucklanes? | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 716 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
It will love Flyin J diesel,the buses cost 3 to 400 to fill-up....shocking... | ||
| norcal kyle (Kylexisxrad)
Registered Member Username: Kylexisxrad Post Number: 119 Registered: 12-2005 Posted From: 216.220.208.233 Rating: N/A |
I use the truck lanes when I use truck stops. but the closest truckstop to me is something like 25mi, so I just use the regular old Chevron station down I-5. it has a mcdonalds, so I just stick the nozzle in and go eat, then come back to a full bus. kyle in norcal | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 717 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
I know he's just jokeing,but don't anybody get the idea that you can leave your nozzel unattended, a fuel spill of a gallon,will get you the police and the fire departmet,and a bunch of paperwork | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 212 Registered: 7-2006 Posted From: 66.217.108.110 Rating: N/A |
At 3 bucks a gallon, I'd be out there with a sponge. | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 718 Registered: 7-2006 Posted From: 64.136.49.228 Rating: N/A |
over a gallon & there is a possibilty of a FINE diesel is considered a hazardus waste | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 5 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
doenst the punp have an automatic shutoff??? | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 6 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
o and can i be "rough" with the 4106 or do i need to pamper the engine by never ever flooring it. i have a 31 ft rv class a ford 450 v10 gas engine now and have 200100 miles on it and am pampering it to death----serviced every month after a trip oil changes every 3000 miles o and don't i get like 1 cent a gallon of if i use my rvcard from flying j??? dutch | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 95 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
Dutch, Yes, you get a penney off from Flying J. You will probably get better fuel mileage from your 4106 than you are getting from your gasser. A heavy duty diesel engine is a whole different animal from a gas engine. All diesels have a governor which actually controls the amount of fuel injected into the engine. The governor keeps the engine at idle speed regardless of auxiliary load, and will not let it over-rev at full throttle with NO LOAD! You can put the trans in neutral and floor the throttle, the engine will go to full governed speed, (factory setting 2100RPM) and stay there, it won't blow up. The governor also "tries to do what it is told." Essentially, if you are at 3/4 throttle pedal, the governor will try to make the engine go to about 1700RPM, more or less. It will move the "fuel rack" which is the linkage between the governor and the eight individual unit injectors, to provide the amount of fuel it thinks it needs to make the engine speed asked for by your foot. So, if the engine is turning 1300-1500RPM with 3/4 throttle pedal, THE GOVERNOR WILL HAVE THE RACK IN FULL FUEL POSITION! Likewise, at 2000RPM and 1/4 pedal, the rack will be in the NO fuel position. Detroit factory recommended oil is 40 weight, be ready for about an eight gallon change! If you are not familiar with air brakes, please get familiar before you depart. These buses came with "DD3" type air brakes. Many of us will be glad to help off board. Be also aware that the engine is stopped with air pressure, and will not stop by just turning off the switch until air pressure builds up to 70-90lbs. This is an air ride bus, DO NOT GO UNDER IT WHILE AT NORMAL RIDE HEIGHT WITHOUT BLOCKING IT SECURELY AT THE JACKING POINTS! Have your mechanic explain the emergecy shutdown flapper and its latch. A diesel without Jake brake gives no compression braking when compared to a gas engine with the throttle closed, please see the recent posts about Jake buffer switch setting etc for several good explanations, descend hills in the same gear you ascended them! There's a whole lot more... George | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 7 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
he george thanks for the info,i will barely do any maintenance on it ,,i will bring it to a mechanic after every trip. although i want to be able to do the basics:oil and coolant service. | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 215 Registered: 7-2006 Posted From: 66.217.108.110 Rating: N/A |
I keep reading and re-reading this stuff about: "....A diesel..... gives no compression braking....", and wonder how in all hell I was able to bring the Eagle to a damn near full stop, by down-gearing and using the engine, alone. I can't count the trips the damned skinner valve would freeze on the way up to the ski slopes, leaving the driver without any means of stopping (aside from the mechanical hand brake). When that engine's in first, it doesn't move unless you want it to. Hell, you can't even "roll start" it, using first..... Wazzup? | ||
| norcal kyle (Kylexisxrad)
Registered Member Username: Kylexisxrad Post Number: 120 Registered: 12-2005 Posted From: 216.220.208.232 Rating: N/A |
lol, I actually was kidding about leaving the bus. I bring the mcdonalds BACK to the bus. nothin' like the smell of a 99 cent dbl cheeseburger and diesel #2. although, the downside to filling @ a car stop as opposed to the truck stops(where the truckers could care less about the bus) is that you are GUARANTEED to hear the same three questions EVERY time you get fuel: "are you a band?", "where are you heading", and "how much to fill that thing up?". I think I'm just gonna paint the answers on the side of my bus and just point at it. ha kyle in norcal | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1843 Registered: 1-2001 Posted From: 75.108.87.29 Rating: N/A |
Kyle, the one I got the most was "who you haulin' in there", from even the gals at the toll booths. LOL Richard | ||
| John Feld (Wvobus)
Registered Member Username: Wvobus Post Number: 13 Registered: 2-2005 Posted From: 204.184.224.34 Rating: N/A |
DML, tell em Elvis' Twin brother. | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1049 Registered: 5-2001 Posted From: 65.74.69.234 Rating: N/A |
Dutch, if the cooling system is clean and the engine is anything like normal, you will be really surprised at the difference between your motorhome and the 4106. Only some of these buses had DD3s. AFAIK, they were an option. The OEM handbrake is a parking brake, not much as an emergency brake. If oily, it won't hold very well even when set very hard. When George says that the diesel engine doesn't have much compression braking, he's comparing it to lighter vehicles. The real problem is you are looking at a vehicle that will weigh twice as much as your motorhome; it takes a lot to stop one on a downgrade. Our choice was to install spring brakes because that was what I was used to. I didn't like the price of the DD3s and I thought that not being able to stop on a downgrade if a hose or diaphragm blew on one of the rear pots was unacceptable. The stock ICC valve depends on the rear pots holding air; if they don't, you will have no emergency brake. I'm sure that the designers were figuring the the loss of air would not be too sudden to get parked. I wasn't willing to count on that. The bus has been optimized to beat it down the road and it handles much better than an ordinary motorhome. If the engine is not seriously worn, it should have no trouble getting better fuel mileage than your motorhome. With a worn engine, two stokes lose fuel economy much more than four strokes; they can come close to getting half the fuel mileage when worn out. It seems to me that you need to drive one; I think that the "sportscar of buses" will sell itself. Good luck. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska (Message edited by pvcces on February 21, 2007) | ||
| dutch (Dutch)
Registered Member Username: Dutch Post Number: 8 Registered: 2-2007 Posted From: 24.27.63.2 Rating: N/A |
thanks for all the help sofar i think im going for the gm4106 but first to a mechanic in town for an evaluation | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 96 Registered: 8-2006 Posted From: 207.231.81.154 Rating: |
To John MC9, In regard to "WAZZUP." In the post: "Expected fuel mileage" a while back, I was the poster who suggested being careful about descending grades (especially with new drivers in an old bus) due to a diesel engine having no compression braking. Yours was one of several later posts asking questions, so I undertook a detailed explanation several posts later. Now, under a different topic, we have another new-to-bus driver going to take a new-to-him bus on a thousand mile first trip. He has stated that his present RV is powered by a 460 Ford gas engine. So, I again cautioned a new diesel bus driver to be careful going down hills because a diesel has no compression braking, compared to a gas engine. Under "EXPECTED FUEL MILEAGE," please read the post by Chuck Brush dated 1/31, 12:21am, and yours of 1/31, 7;41am, Tom Caffrey's of 1/31, 10:21, and mine of 2/2, 12:15. Please then go to the post" "JAKE BRAKE SMOKE" and read the post by Bill Gerrie dated 2/19, 12:44pm, especially the second paragraph! Later in that post, I made another detailed explanation of Jake brake operation, and got a lot of comments! The two I enjoyed the most were the one about "Thanks for not having to have a sitdown, and avoiding a lot of energy consuming thought!" The other was about "a diesel being a big air spring." You are talking about an Eagle, so we will assume it is a two-cycle Detroit? Starting with the piston at the bottom of the cylinder, it is clear of the intake ports, the exhaust valves are open, and the blower pushes air into the cylinder. As the crankshaft pushes the piston upwards, it covers the ports, and the camshaft allows the springs to close the valves. Then, as the piston is pushed up the cylinder, it compresses the air in it to a high pressure. As the crankshaft moves over top center and allows the piston to start moving down, ALL OF THE PRESSURE DEVELOPED BY THE UPWARD STROKE PUSHES THE PISTON BACK DOWN. So, all of the energy consumed on the upward stroke is re-invested on the downward stroke. Now, every engine has friction loss, some heat from the high compression pressure is absorbed by the cylinder head, which will lower the downward pressure SLIGHTLY, the Detroit has a blower which must be powered, in addition to a water pump, an oil pump, a fuel pump, a two-cylinder air compressor, (and since we're splitting hairs here,) only loaded part of the time, but still moving two pistons up and down all the time, some kind of LARGE radiator fan, an alternator, maybe two? maybe a power steering pump, and maybe an air conditioning compressor? All of this is called auxiliary or parasitic load. The same thing happens with a four-cycle diesel, only slightly differently. At the top of the intake stroke, the intake valve is open, and there is no intake restriction, so the crankshaft pulls the piston down easily, filling the cylinder with air. At the bottom of the intake stroke, the intake valve closes, and the piston is pushed up on the compression stroke. Again at the top of the compression stroke, the piston is pushing against high pressure compressed air. It took a lot of energy to compress this air, but now the crank moves over top center to the power stroke, which allows said compressed air to push the piston back down, re-investing the same energy it took to compress it!!! On the exhaust stroke, the exhaust valve opens, and the piston pushes out the air it took in on the intake stroke. The net result? DARN NEAR NOTHING, EXCEPT FOR THE AUXILIARY LOADS, HEAT AND FRICTION, same as a 2-stroke. I won't even mention the rolling resistance of at least 6 big stiff tires, or the wind resistance of a big flat front. Bottom line? I don't deny (AND NEVER SAID) that a bus won't go downhill in 1st gear at idle speed. I know mine will, and at 70MPH downhill, with 12 cylinders, the engine braking is SQUAT. The whole operating practice, theory, or function of Jake brakes is to remove the compressed air from the cylinder at the top of the power stroke, so it doesn't push the piston back down. Then, energy is consumed pushing the piston up, and blown out the exhaust manifold as hot, noisy, compressed air. Compression braking in a gas engine, or a diesel without Jake brake, is a misnomer, but that's what everybody calls it. That's WAZZUP! In reading this preview, I realized that I omitted thanks to SEVERAL PEOPLE who said thanks for the other explanation, I blew it, and your thanks mean a lot! Thanks again!! George | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 218 Registered: 7-2006 Posted From: 66.217.107.177 Rating: N/A |
Just read your "profile", George.... Neat! Say, without attempting to cause any argument.... And trying my very best, not to play my usual role as "Devil's Advocate" wearing my full Don Quixote uniform.... It almost appears that there's a tough course of semantics at work here... You stated the following: 1. "I don't deny (AND NEVER SAID) that a bus won't go downhill in 1st gear at idle speed. " 2. "Compression braking in a gas engine, or a diesel without Jake brake, is a misnomer, but that's what everybody calls it. That's WAZZUP! " Since there's such a roar being made about calling that phenomena "engine braking", or "compression braking", what exactly should all unknowing, uneducated, or otherwise "unqualified" individuals (as myself), call the phenomena of the engine holding 11 tons back whilst descending a steep grade? What -is- the correct terminology, George? I seriously never gave this topic much thought... I just knew it happens... Kinda' like a bowel movement.. Or in this instance... constipation. | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 726 Registered: 7-2006 Posted From: 64.136.26.225 Rating: N/A |
I too don't want to start an arguement,but,buses go down hills just fine,not anything like a 80,000 pound truck,HONESTLY,do not see the need for jakes, | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 15 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
Hey George, Diesel don't hold back? Just for fun, next time you are going down a nice steep 5 mile grade in what ever gear you feel comfortable, half way down kick it into neutral. According to your theory there would be little to no difference, right? Let us know how it turns out. Tongue firmly in cheek. If this is your normal downhill procedure- "at 70MPH downhill, with 12 cylinders, the engine braking is SQUAT. " - you must be used to 'thrills on hills'. Seriously, I don't see why people seem to want to scare newbie/wannabes with brake issues. These coaches work just fine uphill and downhill. They have carried people around for billions of miles. Are there things you need to know? Sure. Do you need to inspect and maintain them? Maybe more so considering their age. Mine is 40! Do you have things to learn if you are not in the habit of hustling 30 or 40 foot vehicles around, you bet. Does this make me want to hump up and down hills in a nice modern S&S instead of the bus, no way! PS We are a two bus family. First bus has a 478 GAS engine with a 5 speed . Other one is a 07 with 8V71 4 speed no jake. Both have air brakes. Gas rig weighs about 11 tons, 07 is stripped and would guess about the same. 07 does better going downhill. Huge difference? No. Real world, yes. (Message edited by doninwa on February 22, 2007) | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 727 Registered: 7-2006 Posted From: 64.136.26.225 Rating: |
anybody can drive a s&s....it's more fun to get your clothes ripped off in Wal-mart by some lady that thinks you are Conway Twitty | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 16 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
Bob, the truth eventually comes out. Now everybody knows why you REALLY drive the bus.  | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 219 Registered: 7-2006 Posted From: 66.217.107.177 Rating: N/A |
If you look like Twitty -now-, they'd have to fight the worms for yer duds....... "Monday, June 7, 1993... Conway Twitty's unexpected demise provided a once-in-a-lifetime opportunity. Country's answer to Neil Diamond had collapsed and died on his tour bus - appropriately enough, in Branson, Missouri -- while headed home to his "Twitty City" complex in Hendersonville, Tennessee. The bus now sat parked in the driveway of Twitty City, a macabre photo opportunity on a par with a glimpse of Elvis's bathroom during a Graceland tour. " Twittys bus  Nice bus, ehh.... | ||
| Bob greenwood (Bob_greenwood)
Registered Member Username: Bob_greenwood Post Number: 728 Registered: 7-2006 Posted From: 64.136.27.229 Rating: N/A |
well... I don't think I look like him...but have had other people say the same..it's funny now..but when those two guys grabbed me,it wasn't..finally,they realized I was not attacking her...SHE was attacking me | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 220 Registered: 7-2006 Posted From: 66.217.107.193 Rating: N/A |
Yeah, I know what you mean! Some gals tore at my clothes at a Target store, thinking I was some famous character... I don't know why..... Here's one of my pics from a few years back:  HEY DUTCH... I'd buy that '06, if I thought I could trust my uncle.. For 5k, you could always sell it again and not lose a dime. (Message edited by john_mc9 on February 22, 2007) | ||
| David Evans (Dmd)
Registered Member Username: Dmd Post Number: 147 Registered: 10-2004 Posted From: 71.125.61.116 Rating: N/A |
Its hard to get my paper work done with this board around!! Get the 06 from your Uncle. Fuel at truckstops but remember they are making a living.Its usually normal to pull foward after filling up and then go pay. Drive your bus with the accelerator, you gotta look ahead and anticipate and watch everthing. Have fun and good luck. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 98 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
John and Don, With tongue in cheek, (we won't get into thumbs) PLEASE read both mine and Bill's posts carefully again. What I have said is not my theory, its high school auto shop. I will gladly discuss this with you at length, but please now offer your explanation of why a diesel holds back. Also, let me answer part of this with a question of my own. IF diesels held back well, why was all of the research and developement money spent by the Jacobs Company, and why do the vast majority of the trucking and bus companies pay the considerable amount of money they do to have Jakes installed? Also, why do Jacobs, Pac-Brake, and Banks make exhaust brakes for diesel pickups? Why do Allison and Telma among others make retarders? Now, the whole bottom half of my post describes energy consumed by: water pumps, oil pumps, fuel pumps, alternators, radiator fans, air compressors, power steering pumps, air conditioning compressors, etc. Driving all of that takes energy, it uses fuel going flat or uphill, and it helps slow down going downhill. Like it or not, the retarding effort generated by a gas engine comes from the effort required to pull the piston down on the intake stroke against a vacuum. As the valves are closed on both the compression and the power strokes, there is no net energy consumed. The exhaust valve opens at the start of the exhaust stroke, which nullifies the small vacuum left over from the intake stroke. Net result? One stroke out of four consumes energy. In a diesel, NO intake restriction, so NO energy consumed, (Other than everything I've already listed.) I know, somebody tried to compare a Chevy Suburban to a Buffalo, I'm still trying to figure that one out!!! WAZZUP is now the bottom of a beer can! CU-ATABOW! | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1848 Registered: 1-2001 Posted From: 75.108.79.35 Rating: N/A |
George, please review the post regarding Jake Brake smoke and discuss what your feeling is about Dale and my posts regarding Jake operation. Richard | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 17 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
Just for fun. Why are there Jakes? $$$$$$$$$$ Saves Brakes.$$$$$$ Lets you go down hill in very heavy rigs faster, time is money.$$$$$ Companies such as Jacobs found something that had a market.$$$$$$ Do all trucks have jakes? No, it is an accessory, a convenience. Why do diesel pickups owners have/want exhaust brakes? Some can use them because they pull weight. Some like more toys. Speaking of reading the posts, as I said I have a GAS and a DD bus that are similar in weight and displacement. No theory. DD has better compression braking. I also have a Semi tractor sans jake. Works just fine going down hill. Just not as fast as it would with a jake. That time thing again. The main holes in your argument are; Gas engine has little/nothing to compress because throttle plate is almost closed. Gas engines maintain some fuel and combustion because, among other things, exhaust valves don't like sudden cooling. Diesel engines fire because they create a whole bunch of heat when they ingest a full charge of air on every compression stroke. If you watch the pyrometer when going down hill you will see the exhaust is pretty cool. Why? The heat of the compression stroke is carried away by the coolant and oil. Net effect is energy consumed by the engine. Now before you tell me that the cooling system can't move that much heat that quick, remember how much it carries away under full power. A little experiment for you. Find a rose gun, you know, looks like a grease gun but is used to put oil in a diff, ect. You will find if you plug the hose you can suck a pretty good vacuum by pulling on the handle. Much like a gas engine. How hard did you have to pull? Does it get warm? Cool? Now fill the gun with air and compress it oh say 18 -22 times like a diesel. You will only need to push hard enough to create about 425-515PSI (DA Book). You can push 1200-1500 or so pounds can't you? When you get to 500 or so PSI grab the tube at the compressed end. What you say? Its VERY hot. Hot enough to cause diesel to fire, right? Which requires more energy? If you don't have a rose gun and 800lb gorilla handy, block the intake of you shop compressor with your hand. Feel the vacuum? Air cleaner housing get hot? Get cold? Now touch the output of the compressor after it's been running a while making all of 120 or so PSI. Warm? Down right hot? Happy trails, with or without jakes. | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1054 Registered: 5-2001 Posted From: 65.74.64.138 Rating: N/A |
Don, I think you covered the energy comparison very nicely! Thanks. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 223 Registered: 7-2006 Posted From: 66.217.106.156 Rating: N/A |
(Thanks Don.) George - You asked: "IF diesels held back well, why was all of the research and developement money spent by the Jacobs Company, and why do the vast majority of the trucking and bus companies pay the considerable amount of money they do to have Jakes installed?" How about: To save the expense of brake shoe/pad replacement? Most of today's companies like to hire "new" drivers; drivers that will work for less money. The Jacob system saves the brakes from the wear an inexperienced driver will give it. It's the same reason most of the outfits have moved to automatic transmissions. Less wear and tear on clutch discs and plates.... and tranny gears. Try to roll start your bus George.. Put it in first gear, depress the clutch, and roll it to 15-20 mph and let out that clutch. OH ... and wear a hard hat, willya? It'll keep your head intact when it bounces off the windshield (a certain gal will probably jump in now, and tell you that if you wear your seatbelt, you won't wouldn't need that hard hat). Why do you suppose the bus damned near stopped dead in it's tracks? You think that maybe the engine's compression did that? Or was it (as you pointed out): "the Detroit has a blower which must be powered, in addition to a water pump, an oil pump, a fuel pump, a two-cylinder air compressor, (and since we're splitting hairs here,) only loaded part of the time, but still moving two pistons up and down all the time, some kind of LARGE radiator fan, an alternator, maybe two? maybe a power steering pump, and maybe an air conditioning compressor? All of this is called auxiliary or parasitic load. " Really George? A "parasitic load" is what's stopping 11 tons dead in it's tracks... at a slow roll, with nothing on and running? Really.... Seriously George... Since we can't call it "compression braking", or even "engine braking", what exactly is it called? Give me a clue... (I'm serious) | ||
| Christy Hicks (Christyhicks)
Registered Member Username: Christyhicks Post Number: 21 Registered: 1-2007 Posted From: 65.77.66.1 Rating: N/A |
<It'll keep your head intact when it bounces off the windshield (a certain gal will probably jump in now, and tell you that if you wear your seatbelt, you won't wouldn't need that hard hat).> HAHAHAAHAHA, thanks for that tip, . . .something I can use in the future ;-) Christy | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1850 Registered: 1-2001 Posted From: 75.108.79.35 Rating: N/A |
I believe that anyone that would put a vehicle in first gear to try and bump start it has little or no experience in bump starting automobiles or busses. On the older cars in the 40's and 50's, we always bump started in second gear. When I had to bump start my 4104 a few times we used a regular pickup to get it rolling about 20 mph. With the tranny in third gear you release the clutch and the 6-71 starts very nicely with no big jerk. You kids just need to learn what many of us old timers have known for years. LOL Richard | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 225 Registered: 7-2006 Posted From: 66.217.107.198 Rating: N/A |
Ahhh... Richard... That "example" was only intended to show George what engine compression is all about. Second gear (or higher) is what's used to roll start a diesel... Hell, even the Mercedes, our Peugeots, or the Jetta diesels we had, wouldn't roll too easily (if at all) in first gear without the engine running. I can't say that for any gas powered vehicle I've owned. I learned quickly, not to down-gear any diesel vehicle on ice or snow.. That enormous amount of engine compression can lock up the wheels as well as the brakes can. I think there's really no argument going here, except for the terminology used in the explanation of what the Jakes do. If anyone is totally unfamiliar with driving a diesel vehicle as big as a bus, they shouldn't be frightened into believing that without the addition of a Jake, or a Telma system, they'd have no other means to slow or stop the vehicle in the event of a brake failure. Having brake systems freeze (in the winter), and fail, wasn't all that unusual years back. We managed quite nicely to have full control, in spite of a frozen brake system. Not too many bus companies ran Jakes, and the reasons for not running them were fairly well known.... The noise factor was one of the main reasons... There were a lot more "line runs" traversing our countryside years back, and a whole lot more buses being used daily; Not disturbing people and passengers, was the main goal. But I believe there was also a safety factor involved.. Greyhound and Trailways drove north to south with the same buses. The use of a jake on icy ground could be disastrous. It only takes one time forgetting it's on, to lose the world's most precious cargo.. George claims that there's more usage of Jakes in commercial buses today..... Hmmm.... I wonder of that would explain the higher bus accident rate (during the winter months) we read about? It was rare, very rare... to hear of a bus crash years back... Oh well.... just an idle observation... don't mind me.. I digress.. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 102 Registered: 8-2006 Posted From: 207.231.81.154 Rating: N/A |
John, MY lady doesn't think much of your post of "Roll up to 20 and dump the clutch in first," either. Actually her comments are un-printable on this board. Once again, I have never said that a bus won't hold back in either 1st or second gear, they will. However, take yours or mine over the top of a grade at 70 with a reasonable load, and you will be on the brakes all the way down. Do us all a favor, and go over to "Jake Brake Smoke," scroll down to Len Silva's post of the Jacobs link, use it, and go to the frequently asked questions section. There, please go all the way through it, including the reason Clessie Cummins developed it. Then I will galdly discuss it with you further in a positive manner if you wish. Poor weather conditions and poor drivers cause wrecks, not Jake brakes. Then comes a post from someone who starts out: "The main holes in your argument are:" In the first paragraph, he says "Gas engine has little/nothing to compress... Then down in the bottom of the fourth paragraph, he asks "how hard did you have to pull?" (He's talking about pulling a Rose gun [AGAINST A VACUUM] WHICH MIGHT JUST BE WHAT I HAVE SAID ABOUT GAS ENGINE BRAKING ALL ALONG?)The second sentence of the second paragraph says, and I'm really having trouble staying civil, "If you watch the pyrometer when going downhill you will see the exhaust is pretty cool. Why? The heat of the compression stroke is carried away by the coolant and oil." (We all understand that a pyrometer measures exhaust gas temperature?) Well Don, I didn't just fall off the turnip truck you profess to have driven, but I AM QUITE CERTAIN THAT THE REASON THE EXHAUST IS "PRETTY COOL" WHILE GOING DOWNHILL IS BECAUSE THE THROTTLE IS CLOSED, AND THERE IS NO FUEL BEING INJECTED, OR BURNED!!!!! Duh! You expect me and the rest of the board to believe what? I know, John says "I seriously never gave this topic much thought...I just knew it happens..." Now, I am going to respond to you in the same way you responded to me. What do Rose guns, shop air compressors, and 800 pound gorillas have to do with diesel engine operation? The holes are in his argument, sorry, but here goes. One more time, remembering all of what you have tried to say, and I do get what you are trying to prove, you only miss the second half. At the bottom of the compression stroke, the cylinder is full of ambient (outside) temperature air, at essentially no pressure. The piston is pushed up by the crankshaft, greatly compressing the air and raising its temperature. This takes (or wastes) considerable energy. At top center, the crankshaft allows the piston to be pushed back down on what would be the power stroke by the aforementioned compressed air, so this energy is re-invested. ARE YOU WITH ME? All valves have stayed closed, right? Piston has compressed and decompressed the cylinder, still with me? What is the NET change? Some heat has indeed gone into the head and the piston, and through the piston into the oil spray on the bottom of the piston. But you have to admit, using your air compressor and Rose gun comparison, that when you decompress the air in the cylinder, it loses the built up temperature. Now, do you agree that air expands as it gets warmer? Also that it contracts as it gets cooler? We can't get beyond this if you don't. So, what is the NET change? Due to the heat loss, the pressure is very definitely SLIGHTLY LESS on the down, or what would have been the power stroke. I'm not a physicist, I can't quote you the number, but it is not significant. This gets me to the whole point of why Jake brakes were invented, and PLEASE read Len's link that I mentioned above, because Jacobs explains it very well. I'm done, and like the steer said, I tried. | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 227 Registered: 7-2006 Posted From: 66.217.106.212 Rating: N/A |
George - You're using a ton of pixels here, and totally missing the point. You said (boldly): "Once again, I have never said that a bus won't hold back in either 1st or second gear, they will. " Great! Good start. My question to you was simple: What do you call that power the engine displaces in 1st, 2nd, or 3rd gear, that enables us to slow the vehicle down, using those gears while not applying fuel? Simple question George. And the reason I ask it, is to clear the dysfunctional air that manages to permeate this place, every time someone says that a diesel has -0- compression braking. A diesel has an enormous amount of braking power, if the vehicle is in the correct gear for the job. You've got yerself worked into a dither... Relax man, life's short. It's clear that you have a great understanding of "how things work". (I've picked up a few things from you, but I hated to tell you) Did you ever hear ther comment: "engineers should never write instruction manuals"? Now ya'know why. HAR! But please.... answer that question that's left hanging? If it's going to drive you crazy everytime a person refers to using the engine to stop his bus, as using it's "engine braking power", then you better help devise a better term to use. | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 18 Registered: 1-2007 Posted From: 65.61.96.82 Rating: N/A |
I need to have a heart to heart talk with the 8V71 in my 4107 and convince it that even thought it really wants to, it has to stop holding back more than the 478 in my gas bus. Would not want it to PROVE your THEORY wrong. I have avoided trying to compare big rig diesels to gas since there are not many 11 or 12 liter gas engines to compare. This is as close as I can come. My son's pickup that we changed from a 6.2 diesel to a 454 gas with same tranny/gearing does not have as much compression braking now either. Something must be wrong with the 454, it has more cubic inches, it goes like crazy, just does not exhibit MORE compression braking to support your THEORY. I've had three 5.7 GMC diesel rigs. Many 5.7 gas rigs and they, the gas rigs, all had/have less compression braking. Exact same displacement. No theory there. My other son, the Diesel Heavy Equipment Mechanic----Never mind, no use mudding the water with facts. I give! Suppose I should send my 30+ year CDL back the the DOL. I must be a menace. | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1056 Registered: 5-2001 Posted From: 65.74.64.138 Rating: N/A |
George, I think what got you into trouble on this thread was thinking that the loss of heat energy into the cylinder head and block was not very significant. I believe that it is significant and the major reason that diesel engines have the compression braking that they do; it's the parasitic loads that are not very significant on a long downgrade. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Tim Hoskinson (Tdh37514151)
Registered Member Username: Tdh37514151 Post Number: 210 Registered: 9-2004 Posted From: 4.253.121.76 Rating: |
Hi everone at the risk of getting my self in trouble here I wanted to just offer a thought or two. As I read down through the posts I find at least one fact missing. Really George is correct in his anaolgy of how all this works. One point that can be added is that most buses out there do have some wear on the engine not all but alot do. The compression in any engine will leak off to a degree of course more in a worn engine only slightly in a fresh one. The leaking of compression can cause a slight differential in the compression to decompression alowing for a small amount of possible engine restriction. Along with that as George said you also have parasitic loads. All of these loads don't amount to much when looking at them from the engines torque perspective to the drive line. Normally the ring and pinion multiply the engines torque to the wheels. In the case of engine restriction to the wheels the torque must now overcome the reverse gearing up of the rotation from the wheels to the engine. This greatly mutiplies any restriction present. I hope this explanes some of George's point and while you certainly do get some restriction from the engine it is greatly increased by a Jake brake's method of releasing the compression at just the right time. As George had stated. I hope we can try to learn from everones posts and not tear at each other as I know for sure we can all learn form anyone if we choose to listen think over what they have to say and consider that we our selfs may have missed something leading us to not understand. Best of luck to all Tim (Message edited by tdh37514151 on February 28, 2007) | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 477 Registered: 10-2003 Posted From: 71.58.117.21 Rating: N/A |
Let's see 2,500000 divided by 24 years equal 104,166 per year divided by 52 weeks equal 2000 miles per week or 285 per day, or probably 400miles per day with downtime. Man, that is a lot of driving.Wonder how many overhauls, and tires replaced? |
