| Author | Message | ||
| John Rigbyj
Rating: N/A |
After installing the new radiator, fan and shroud where would I go or what would I do to give the system a good check out? living on the gulf coast I-10 corridor It is imposible to find the kind of mountains for a good check out. When the price of fuel drops, and I take another trip out west. I dont want to find out I still have problems?? | ||
| S.M. Heath (Hotspring_44)
Rating: N/A |
Re: ("When the price of fuel drops",)... I absolutly love the optimisim!!! Thanks John R. S.M.H. | ||
| jimmci9 #2 Rating: N/A |
use an infrared thermometer... measure the top tank temperature.. then measure the bottom tank...make sure that the tanks are similar in color.. (both black, rusty, etc)... a good system will have about a 12-15 degree drop....more differential means a coolant flow problem (like a stopped up cooling system or thermostats stuck shut, for example)... less differential means that either the coolant is free-flowing (like stuck open thermostats) or your fan isn't moving enough air....other than that, make sure you have a 60/40 mix... and keep the coolant conditioned properly... test strips are available at cat, cummins and dd dealers.... | ||
| Gary McFarland (Gearheadgary)
Rating: N/A |
Man, that's one good tip. Jim, you should consider doing this stuff for a living. Gary | ||
| John that newguy Rating: N/A |
Hey Jim... One the '79 MC9 I have, there's an air scoop attached to the outside vent for each of the radiators. I assume these are some sort of after market device (?), and would like to know if they're a needed option, or if it's safe to remove the clumsy looking scoops? | ||
| RJ Long (Rjlong)
Rating: N/A |
John TNG - If your cooling system is serviced properly, and all the various rubber seals are in place, those scoops are unnecessary (besides being ugly!!). Most overheating problems, with MCIs in particular, is operator error anyway! An interesting trick to increase the air flow into the radiators is to install a piece of 3/4" or 1" aluminum angle iron vertically along the front edge of the radiator opening. This breaks up the laminar air flowing along the side of the coach, and the back side creates a little more vacuum for the air to be sucked into the rads. One other idea, borrowed from GMC, is a "mudflap" completely across the rear of the coach just behind the tag axle. This flap creates a low pressure area behind it, helping to draw more air thru the engine compartment while running at highway speeds, and is unobtrusive. The WORST thing you can do, especially on an MCI, is hang one of those mudflap things off the back bumper "to keep the toad clean". That helps trap the hot air in the engine compartment, which is what you DON'T want. And I agree with Jim about using the infrared thermometer! HTH, RJ PD4106-2784 Fresno CA | ||
| Dave Wheat
Rating: N/A |
Air Scoops on the MCI: On the MCI's our company had here in MN we drove with the air scoops attached in the summer and without scoops in the winter. A little added insurance for better air flow in the summer was nice to have. D Wheat | ||
| jimmci9 #2 Rating: N/A |
ive seen scoops on mci7's and 8's... they had smaller radiators, slower blowers... maybe some other differences from the mci9's... my '81 mci9 doesn't have the scoops... kinda wish it did... if you decide that you don't want yours. i'll take 'em.... | ||
| Craig Smith (Craigs)
Rating: N/A |
By coincidence, my 1975 MC8 has scoops and it originally came from AZ. I also have the smaller radiators and the slower blowers. But, my cooling system works good. Craig S | ||
| Glenn-MC-9 Rating: N/A |
Our singing group recently purchased a 1984 MC-9 "Jersey Cruiser" that has "air scoops". I don't know if they were put on in New Jersey or added later. The best that I can find out, Lewis Bus Lines in Augusta, Ga. bought it at auction. I heard stories from other groups about there 9's heating up, but ours, even with the "coach air" on doesn't get up over 180 degrees. This past Sunday night the temperature here was in the middle 50's, and with me pulling several hills coming in our engine temperature stayed around 170 degrees. I wonder if the scoops were off would it have made much difference? Glenn Tallulah Falls, Ga. | ||
| John that newguy Rating: N/A |
Ok. I ripped 'em off and the bus looks better, but after reading all the comments, I'm tossing 'em in the bay until I'm sure I don't need the things. They're ugly as sin and I'm going to hate like hell putting 'em back on, if I end up having to. Thanks guys. | ||
| H3 (Ace)
Rating: N/A |
Your probably not wanting to hear this but I think your better off with the scoops, in the long run. One reason the scoops help is due to the side of the bus not allowing the air to enter the open area of the radiator door. It has something to do with turbulance. I think you will find that if the air entered an open door near the front of the bus say right in front of or behind the front wheel, it would enter cleanly, but once the air is deflected off the side of the bus at or near that area it doesn't come back to the bus's side until almost the very end or rear and missing the stock open radiator door completely or maybe sucking in very little if any. Next time your driving your bus in a light rain, look in the mirror and notice the flow of water on the sides. That can show you in a sense how the air hits the side of the bus. Some water gets bolwn off and some appears to never get touched though your speed never changes! I may not have described this clearly but it all has to do with aerodynamics! Same thing applies to race cars and air flow! They use Naca Ducts in numerous places on the side to draw and direct air INTO places that would never get air due to the sleek body lines. One other example is a Cup car has open windows but still the inside gets very hot. Have you ever seen a driver stick his hand partly out the window net which is on an open window during caution laps? Acts as a scoop to get a little air inside! Same would apply to your bus! HTH Ace | ||
| Marc Bourget Rating: N/A |
Scoops are a band-aid for an old or poorly maintained (both?) cooling system. Air flows in response to a pressure differential. By anology, an air molecule is like a guy on crack stuck in a crowded room, vibrating furiously - but no room to move. The pressure differential "shows up" when someone opens a door and people close to the door begin to leave the room. He starts moving more or less in the direction of the door, accellerating as he gets closer to door (Bernoulli principle) and slows once he "escapes" to an area of higher pressure. Air is never drawn or sucked anyplace, it moves when "room" is made for it, that room being a lower pressure area. If the MCI fans and radiators are clean, perimeter seals maintained and drive belt operaing properly (tensioner), sufficient pressure differential exists to run sufficient air thru the radiators to adequately cool the engine WITHOUT the scoops. All the above was offered to clarify. Ace is correct. Use scoops if you're not inclined or motivated to maintain/repair your system. But keep the consequences in mind. Onward an Upward Marc Bourget | ||
| H3 (Ace)
Rating: N/A |
Air is never drawn or sucked anyplace, it moves when "room" is made for it, that room being a lower pressure area. I "think"  that is what I was trying to say! It was late and brain cells didn't work as well as they should have! The front side of the bus has a lower pressure area just back from the frontal area due to the air being deflected by the flat front. The rear end of the bus has a much higher pressure hence no air moving IN the desired area without the help of a "scoop" of some sort. I would have to dis-agree that scoops are a band- aid due to many applications that are brand new, clean, and eventually maintained, use scoops. Hoods of cars and trucks have scoops. Air filters on semi's have scoops. Look at the sleeper births on older semi's. The little door acted as a scoop when it opened outward, and it opened to the front to scoop air. Drag cars most always have scoops to attract air IN, even the open wheel dragsters with no body use scoops on the open air engines. As I said, Naca ducts used in racing are a scoop, designed to be flat, attract air flow IN BUT still a scoop. As for air never being "sucked" in anyplace. I think if there was a vacuum of sorts it could very easily get sucked IN or OUT. You can do a lot with moving air and expierementation. I designed and mfgr. a scoop to act as a velocity stack on small engines. It actually draws ("sucks") air to IT by means of it's shape. Many different designs were tried before we got what we wanted. Grant the carb creates a vacuum but it never changes. The air flow does! Not a slam, merely a clarification on what I was trying to say! Ace | ||
| John that newguy Rating: N/A |
Hey.. Both explanations are great; both explanations work well to draw the picture. I see plenty of Greyhound's older MC9s down here in Flor-ah-duh zipping by on a daily basis. Some have the scoops, but most do not. By the overall look of the vehicles, I would seriously doubt they have a stringent maintenance schedule. With doors aflappin', clouded front glass, and oil on the ground wherever they stop, I rarely see them sitting in an overheated state aside the road... So.... I guess I'll give it a whirl w/out thew scoops, but I -will- hold onto them until I'm more than sure I don't need them. It's fairly easy to figure out the hows and whys of the scoops, but there are times that operators add things to their units that aren't needed. I guess only time will tell.... | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Gene Rochester (a bus nut who used to post here a lot) did some extensive testing on this problem. IIRC, he determined there was a low pressure area along the side of the bus and this low pressure area tried to draw the air out of the radiator. The scoop acted to break up the air flow along the side of the bus and eliminated the low air pressure area. This allowed the radiator fan to draw more air in and thru the area. This was a couple of years, (or more) ago so I may not have it exactly right. Probably some info in the archives. Richard | ||
| Marc Bourget Rating: N/A |
I shoulda been more accurate. Scoops on a MCI-x cooling system are a band-aid. Note, I didn't say they were wrong, just an interim type, "treat the symptoms not cure the cause" kinda "repair". If scoops are incorporated in the original cooling system design it's because is was intended or needed, for instance, something else is limiting air flow, like fan size or radiator opening size or their position. In MCI's position, the "low pressure" back of the bus affected the engine compartment also, so they attempted to get more cooling air past the engine by dumping the fan exhaust into the compartment. Same as with a side radiator but the way they assembled the engine components and where they put the axles may have had an influence. Even so, OEM scoops can be troubling (I meant to limit that point to cooling system applications) since the low speed cooling criteria is so slow that scoops are rarely a benefit (not "ever" just rarely and there'll be a different reason this is so). Remember the phrase "nature abhors a vacuum" This was a "double entendre", it has two meanings or points. First, air will flow to a low pressure area to relieve the vacuum, and, the second meaning is aimed at making the point there's no such thing as a vacuum. Another example may help. You could say that air would respond to a "vacuum" if the air molecules had little hooks or something like magnetic attraction to eachother. Then you could "suck" or pull air into something like a carburator because the molecules would "pull" each other along. Nitrogen and Oxygen molecules, comprising 90+ % of the air are non-polar molecules and aren't magnetic so there's nothing to pull or "suck" with IYKWIM. You understand how it "behaves" by all the examples you gave. Close enough here for this discussion but someone else might get themselves outta kilter or in a corner in another situation. One such situation might be with NASA ducts. NASA Duct "scoops" are intended for intake of "impact air" NASA ducts work better than scoops only if they're in the correct position - on the front of a part of a moving body that is in the middle of an expanding cross-section. Like on a nose cone of a rocket, not like on the side like a bus. They act to reduce the drag associated with air "collection" they're not some sort of "super scoop". Pound for pound of air delivered, a correctly installed NASA scoops would slow the vehicle down less than an external scoop. And the faster the speed the more the benefit, like on a Mach 3 air to air missle. This isn't to say they're use on the rear quarter window of a Nextel Cup car is wrong, not at all! They're also great for "sex appeal", which is important in its own way! The NASA Duct opening on the flat side of a vehicle just won't have the drag reduction benefit sought after by NASA when they originally designed it. I'm sure the Nextel guys recognize this since they generally dump into a flexible, wound wire duct. The internal drag from such a duct would quickly eat up whatever benefit the NASA Duct gained. Finally, air flowing along the flat side of a bus doesn't exist in a "low pressure" area. The highest pressure is at the front from impact air, the lowest is probably at the corners of the front where the air speeds up as it transitions the corner. Once it's flowing down the sides, it will be at ambient or "normal" pressure. Air pressure along the body in front and in close proximity to the tires will be higher than ambient, lower at the trailing edge of the tires. What happens at the rear is hard to guess because of airflow out of the cooling system is hard to predict but the air along the sides will first "speed up" (pressure falls) when it "falls" into the "hole in the air" made by the bus pushing itself along and pressure will "recover", i.e. increase, when the air from opposite sides starts banging into eachother in the middle. It generally won't get as low as the front corners however, because the speed change at the rear is probably less since the cooling exhaust is expanded by heat and mixed in. It would have to be measured by a sensitive instrument as the overall differences are slight. (I'm talking about the whole setup, averaged out, not what you'd feel by sticking your hand out a window). My resource for this information is an engineer Ph.D. that worked for NASA at the Ames Wind Tunnel(s) Laboratory. He is a wind tunnel expert. During the Cold War his knowledge was considered so valuable, he was visa restricted. They didn't want to worry about the Ruskies kidnapping him! So much for non-bus trivia, but I thought the source of the info might interest the BB in general. Onward and upward Marc Bourget | ||
| Stan Rating: N/A |
Marc: I don't want to get into a long discussion on your theories but I would appreciate an explanation of why the curtains or any loose paper fly out an open side window if the air along the side is at ambient (the same as the inside air). | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Also Marc, Gene Rochester had an opening in the front of his bus which was open to the passenger compartment. At some road speed, the suction was so great that it sucked all his documents lying on the floor out the front of the bus!!. I have to believe this was a low pressure point in the front of the bus. | ||
| Marc Bourget Rating: N/A |
Stan and Richard, I should of thought to include the following information, but the post was pretty long as it was. The example was assuming a sealed body, which was unrealistic on my part and for that I apologise. The simple answer is, in each example, the pressure inside is higher than outside. This is an immutable rule of physics. Why the pressure inside is greater is much more complicated. I'm sure, with a magnahelic guage, or even a cleverly used aircraft airspeed indicator, if I had the chance to inspect and ride in the respective coaches I could find the cause. I've recently been stripping out the interior of my MCI-9, following Gumpydog's lead. The full floor is pulled up and wheelwells disassembled. It's just a big "Cage" inside at this time. I'm amazed at the number, variety and position for, sources of air incursion. Before this I "knew" there was an answer to questions like this (the rule is "immutable" you know!) But I didn't have the ideas of where to look and how many there were, like I do now. Up front below the driver is complex, the bus air channels complicate this times 3 or 4, etc., whether the bus air is operating and pressurizing the interior is also a factor. Remember, the impact air at 100 MPH increases the pressure only 5" of H20, I think someone compared that to the drag upon inhaling a cigarette - a fact I wouldn't know since I've never smoked, but it's still an example. An intake in front, closest to the center of pressure of greater than or equal size to a opening closer to the corner where the air speeds up and pressure drops (Bernoulli again) would witness air flowing out the opening or the window along the side simply because dynamic pressure is greater. Cross wind conditions can complicate this. I rememeber a similar thread where Jack Conrad posted regarding reverse airflow out the black tank. Which window was open vs the wind direction and vehicle speed are all factors. There are so many variables, that it'd probably take 10 pages of describing which window was open, condition of bus air, model of bus, speed, cross wind, etc., and there would still be unknown factors By this description I'm not being evasive or trying to confuse. You have to understand these molecules are like "very tiny marbles" that have very little mass and respond quickly to pressure differences so small only tiny skin hairs can detect the larger, more significant influences on the currents of air. I'll be putting my project on the road as a shell. I've been curious about these in-an-out airflow issues for years. I have a couple of magnahelic guages. I'll be able to test these issues and will report. Hope ya'll will find it interesting! Onward and Upward Marc Bourget | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Thank you, Marc, I like the solid info in your posts. Every busnut would quickly find that an infra-red temp gun is the best tool in your collection. Well worth the money. Mine was CDN$140. Some have reported US$90, much the same. Just about everything that goes wrong on your bus will show heat, or abnormal temperature, before it ultimately fails. Check bearings, tires, fan belts, radiator, heater cores, electric motors, electric wires and connectors, poor grounds, generator air flow temp, insulation, surface temps, interior temps. Lets you compare things precisely, and lets you teach yourself about the mistakes that "common sence" and high school science have installed in our heads. (Please remember that high school dealt with pure theories and didn't allow for real world variable - where out here are you going to find that vacuum to drop the feather and steel ball in?) I might even suggest for the budget minded that an infra-red temp gun is better value than a torque wrench! happy coaching! buswarrior | ||
| John Rigbyj
Rating: N/A |
I understand that the best place to add any form of air interupter on the 4104 is just infront of the radiator,(3.5"X 30"X 1/4" Aluminum flat bar attached vertically just before the radiator )only 1.5" stick out from the side of the coach,the air come along side the bus hits the aluminum is pushed out then goes back in towards the side of the bus. At this time it goes streight in and though the grill and radiator. John | ||
| RJ Long (Rjlong)
Rating: N/A |
Stan - Way back when I drove Crown skoolies (while putting myself thru college), we had to clean out our bus at the end of the day. Many of us would use the "6-50 broom" to do so on our way back to the garage from our last drop: ~ Close all the windows in the coach except the last three on each side. ~ Open the front door. ~ Drive 50 mph for at least one mile, preferrably two. Sure beat trying to wrestle a broom around all those seats. . . (But you DIDN'T hear that from me, OK?!?!?) RJ PD4106-2784 Fresno CA | ||
| RJ Long (Rjlong)
Rating: N/A |
After re-reading some of the posts in this thread, I remembered something else that might be helpful in this discussion. Take a look at this pic. It's a 1964 Chevy Corvair Greenbrier: The third row of seats in this little van was right where the second-to-last side window is located. If you rolled this window down while traveling, the wind would blow right at the side of your face. Now, look in the white stripe area, just below that window and slightly to the rear. It's hard to make out in this small an image, but you can just barely see the cooling air intake grillwork. Bob Benzinger, who was on the Corvair engine development team for Chevy, stated during a Q&A session at one of the national Corvair club conventions that the air intake grill was located at that point on the sides of the "Forward Control" models because it was the point of greatest air pressure along the vehicle's flanks. And yes, this was determined thru wind tunnel testing. A friend of mine in college had one of these, but it was the panel van version, w/o windows behind the front seat. He bought a set of air scoops to put on his van to increase the cooling, just like the ads proclaimed. Shortly after installing them, while running 60-65 mph on a 90 degree day between Chico and Bakersfield, he kept getting the "Hot Engine" idiot light on the dash. He'd pull over, check the oil and fan belt, find they were ok (no radiator - engine was air cooled), then scratch his head in bewilderment. He'd never had that light come on before while making this run, except when he'd flip off a fan belt, which wasn't uncommon on the 'Vairs. He limped on home into Bakersfield, worried that he'd be facing a major repair bill, not something a starving college student needs. While explaining this tale of woe to his father (who just happened to be a Chevy Zone Warranty Technician), they wandered out to the van. Dad immediately noticed the new air scoops, and suggested that son take them off, and see what happens on the return trip to Chico. You guessed it. . . no "Hot Engine" light the whole way. The scoops had actually been impeding the air flow thru the grillwork and therefore the engine compartment, starving the cooling fan and causing the engine to run hot. Just a little anecdote to illustrate an example of this thread's discussion. . . FWIW, RJ PD4106-2784 Fresno CA | ||
| Stan Rating: N/A |
Marc: Try a little experiment. Blow across the end of a straw and you will find the pressure will drop enough in the straw to hold a piece of paper on the opposite end. This is just a miniature example of a bus rushing through the air with a window open. | ||
| H3 (Ace)
Rating: N/A |
I was noticing on our H3 that the air intake has a louvered panel on the RR top corner. This panel is factory and the louvers are angled and flared in a way that would allow air IN to the air filter. I think this would be called some kind of scoop! FWIW Ace | ||
| Marc Bourget Rating: N/A |
Stan, Try the same experiment with the straw filling a carefully sized hole in the center of a sheet of cardboard clipped from a cereal box. Blow on the side of the flat surface with the hole, not both sides of the cardboard. This mimics an open bus window better than the end of a straw in a free air stream. This is a question from curiosity not an attempt to answer a question with a question. I don't have a straw in the house or I'd try it and report. You have a good point but I feel your example doesn't accurately represent the "bus window" situation. If the straw were full of various tiny holes and the full straw subject to the blowing wind - like in a bus, with all the various holes (and their position in the stream of wind) you'd have a point. Your example assumes the bus interior is a sealed body, similar to the simplistic (and incorrect)assumption I made in my first post on this thread. For these reasons (and a bunch more variables) I don't think your example is valid. Don't get me wrong. I believe your results are accurately reported, I just feel that your "experimental model" doesn't fit what we are presented with in a bus. That's why I reserved my opinon on the eariler posts until I could be in the particular bus with my magnahelics while running down the road. Keep in mind, at this point all I have is an opinion based on prior information and I've never done this in a bus. That's why I said above that I'm going to play with this when I get my interior "shell" installed. It will be easiest to control all the different "ins and outs" with a bare floor with no "unsealable" holes in it. That way I can open windows at the four corners, etc. and see what happens. The curtain in the window will be easy to duplicate. Now that I think of it, I'll take the thing to a long grade and do some coasting tests. That way engine noise won't mask the "whistles" IYKWIM. Onward and Upward Marc Bourget | ||
| Stan Rating: N/A |
Marc: You will be quite surprised by how tightly you can seal the bus. I used sprayed in foam everywhere I could put it and just four Peninsula windows. The fresh air intake to the driver's heat system has a door with a seal on the edge. I completely blocked the A/C air intake because I removed the bus A/C and I put bellows on the accelerator and brake rods where they come through the floor. This left no obvious holes and with good window seals it is pretty air tight. If you are interested in low heat-A/C operating cost as well as comfort, you have to eliminate air infiltration as much as possible. | ||
| Marc Bourget Rating: N/A |
Stan, I agree with your point on sealing. At the same time, comments by Gumpydog on his site alerted me to the "sign" or evidence given by air ingress/egress. In disassembling my interior I came across extensive proof that areas suposedly sealed with adhesive tape, putty and other means "magically" allowed air to get in and out. One time I stopped what I was doing and crawled under the bus trying to figure out where the air was coming from - No Luck! I'll be checking further when I pressure spray the interior. Based on the amount of dirt in these "sealed" areas, we're talking about a lot of air flow. I'm looking at achieving as much of a seal as possible by a total strip of the interior, spray foam and paying attention to such things as the pedal shaft bellows you described. I'm not sure if you went this "far" and it will be interesting (if you didn't) to compare the two projects. Mine, a totally insane, overdone 'cuz I was curious about airflow, vs your diligent, practical approach. By the way, I have a MCI-9 what are/were you working on? I want to test the coach with a sealed interior box, no cabinets, penetrations, zip, zero, zilch, nada, as a control, test the coach and then go from there. As far as black tank smell, a magnahelic with one tube in the bays and one in the "cabin" will help determine this issue. Once the tanks are installed and vented, one tube in the vent vs. the cabin and other variations will give accurate data on what's happening. Onward and Upward Marc Bourget | ||
| Stan Rating: N/A |
Marc; I was working on a MC-7 Combo. There is a simple solution to commode odor. Just put a whisper fan in the tank vent pipe that is powered by the commode area light. By the time you are ready to flush the fan has pulled a vaccumn on the tank. The air will rush in with the flush with none coming out. | ||
| John that *&^%guy Rating: N/A |
Marc: "You will be quite surprised by how tightly you can seal the bus. I used sprayed in foam everywhere I could put it and just four Peninsula windows. The fresh air intake to the driver's heat system has a door with a seal on the edge. I completely blocked the A/C air intake because I removed the bus A/C and I put bellows on the accelerator and brake rods where they come through the floor. This left no obvious holes and with good window seals it is pretty air tight. " Gee, Marc.... It sounds like one good fart at the wrong time and you'll blow that windshield across town! | ||
| Marc Bourget Rating: N/A |
To Stan: I agree with the exhaust fan, but was thinking of underway. Jack Conrad's post contemplated smell incursion while underway, not stopped and in use. JohnTNG: I don't know if flatulence alone, without the presence of a lighted match would attain the results you described! We'll have to compare diets, IYKWIM!! Onward and Upward Marc Bourget | ||
| Stan Rating: N/A |
Marc: If the pressure inside is higher than outside as you suggest then it is impossible for odor to come from the outside. If you use deep traps on the fixtures and there is water in the commode it is impossible for odor to come in from the fixtures. | ||
| Marc Bourget Rating: N/A |
Stan, I think I lost track of where you were coming from. The pressure might be higher inside but relative to what?. (more below) I responded to your commode post assuming that the bus was stopped and therefore there was no dynamic pressure. I wouldn't begin to delve into dynamic pressure whether to equip the vent pipe with a fan until I had made some preliminary measurements. Sometimes following the "KISS" principle is complicated! Not to say it doesn't work, just my approach would be different and I wasn't responding to the questioned you asked/comment made. Back to the open window. Air flowing down the flat side of a bus, parallel to the relative wind, assumes ambient pressure, but you introduce another factor/phenomena with the open window, like with the straw. Air flowing past an opening is not air flowing down the side. I was trying to keep apples with apples, etc. when I postulated my "sealed body" example. That example is quite simple and a "real" bus is quite complex to the point it can't be easily predicted. Onward and Upward |