| Author | Message | ||
| Dave Hartshorne (Yeeolde48)
Rating: |
Hi Guys, I know the old 8V71 is supposed to smoke, but just fired up the motor in my Scenicruiser today and it normally smokes at start, but once I get it on high speed the right bank always cleans up almost imediately, and the left bank within about 10 seconds. Today, the right bank was the same as usual, but the left continued to smoke (white). After I had built air pressure, I could reduce the smoke by increasing throttle, but it is still there a whisper, and as soon as I drop back to idle, it starts again. I was not able to take it for a run today to see if warming it up fully clears the problem, but can anyone tell me if this is a common thing for cold weather (about 35 deg. today in Cincinnati), or a sign of something more serious. Any thoughts would be appreciated, I was trying to decide if I pull the drive module to put the auto trans in this spring, and if I have an impending problem in the engine that would swing the decision, and allow me to check it at the same time. Appreciate your experience before I go back tomorrow and take it for a run. Cheers, Dave PD4501-304 | ||
| Bill K Rating: N/A |
May have a leaking head or head gasket or ect. | ||
| TWO DOGS Rating: N/A |
seems like maybe an injector line inside the valve cover might be leaking...rack needs to be run...make sure first thing you check anytime more smoke than usual is The mouse trap...especially if any kids have been in the bus...they like to push any button they can... | ||
| dave4106 Rating: N/A |
anything under around 150 degrees your gonna get smoke. only way to find out is to put a load on it and get the temp up 170- 180. if it doesn't clear up then ,you have a problem but it may not be as serious as a blown head gasket. generally white smoke at (operating temp) means coolant being burned i.e. head gasket, hole in liner etc. darker smoke at operating temp usually a fuel issue. cold weather makes a difference. hope this helps. dave | ||
| Dave Hartshorne (Yeeolde48)
Rating: N/A |
Hi Two Dogs, please excuse my ignorance, I am still new to the bus scene, what do you mean by the mouse trap? My 2 year old was in the bus last week... Thanks, Dave | ||
| Dave Hartshorne (Yeeolde48)
Rating: N/A |
That's 2 year old GRAND SON, I guess I was trying to convince my self I am getting younger not older. Do you mean the emergency shut off? Dave | ||
| TWO DOGS Rating: N/A |
It's the emergency stop...should be on your control panel...it's a switch that activates a flap that covers your air intake...(in case you have a runaway)...it has to be reset once it has been tripped...usually in the tube before your supercharger.... called a mousetrap,cause you set it....it trips when button is pushed & a flap covers the air intake... | ||
| jimmci9 #2 Rating: N/A |
white smoke on start-up is unburned fuel.... several things can cause it.. mainly wear.. 1) an injector being worn enough to not properly atomize the fuel to get a proper spray pattern.. 2) condition of a cylinder---worn rings, sticking rings, poor compression... | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
Dave, if the light or white smoke is made worse when cold, and better when warmer, I would zero in on low compression. Since you got it started, and the white means misfires in some cylinders, I would look for a one or more cylinders to be low, compared to the rest. Since you know which bank, you know which covers to pull for an inspection. A good Detroit man should be able to give you a usable opinion. Tom Caffrey PD4106-2576 Suncatcher | ||
| Dave Hartshorne (Yeeolde48)
Rating: N/A |
Thanks for the information guys. I will see how warm it gets tomorrow and maybe take her for a run to get the motor warmed up, and see if it clears. If not, I found out today that my wife's ex is an old detroit mechanic and would probably come over and take a look at her for me. Cheers, Dave PD4501-304 | ||
| TWO DOGS Rating: N/A |
this is something that just now happened...possibly cold...(GET A BLOCK HEATER) If it was low compresson....it would have been doing it for a while...not low compresson overnight...the mousetrap has two levers...one spring loaded & the other one is the trigger...move the spring loaded one over ,then move the second one to "set" the trap..it should hold the spring loaded one in set position...usually...it's little boys between two & 12....just GOT to push all buttons...lots of smoke...no power...not able to get rpm's | ||
| BrianMCI Rating: N/A |
If white smoke persists at anything CLOSE to normal operating temps it is from water in the combustion chamber and could be from a leaking head gasket as Bill mentioned... Brian | ||
| jimmci9 #2 Rating: N/A |
leaking head gasket will be kinda obvious... it'll put compression in the cooling system... like blowing cooling out of the radiator.... and you'll be smelling glycol.. from antifreeze....lots of guessing going on here... by some really uninformed people, not mechanics....take it somewhere and get a professional, paid-for opinion.... | ||
| busnutphil
Rating: N/A |
how about white smoke that comes out of the breather tube only on my 8v-71. The exhaust is fine, it runs great, but blows tons of white smoke likes its on fire and loses alot of oil. Does it all the time, cold and hot. One retired mechanic told me it could just be the rings are stuck any chance thats all it is?... hopeful, but open to all opinions.. sincerely, busnutphil | ||
| FAST FRED Rating: N/A |
Sounds like it just hasn't been run up to temp in a while. Ideling without going for a ride is slow DEATH for these engines. Start it , get air up and MOVE! at moderate speeds till the water is 140, then you can go faster, above 160 go for IT. Most of these engines are broken in operating near max rpm , highway speed , so low temps really effect the shape and seal of everything. Drive da Bus Mon!! Thats what it was created for! FAST FRED | ||
| Jim in California Rating: N/A |
Put Nicorrette patches on the engine. Stops smoking! | ||
| RJ Long (Rjlong)
Rating: N/A |
Dave - Hope you took your coach out for a 50-100 mile run today. . . what happened?? Did the smoke clear up? Get worse? Turn black? Curious. . . RJ | ||
| Dave Hartshorne (Yeeolde48)
Rating: N/A |
Hi RJ, we got 4 inches of snow last night, so did not take her out today. I am off tomorrow for MLK day and most of the snow has cleared so may get chance, but only if the temp gets a little higher (in the low 30's today. If not it will be a couple of weeks before I get chance again. I have to travel to Orlando for business on Tuesday, then to NY early next week, so will just have to worry about it till then. Will re-post once I get her out. Cheers, Dave PD4501-304 | ||
| busnutphil Rating: N/A |
hey i know the differance between warmned up smoking vs cold. actually i do drive the bus,thouands of miles per year, usually 3-6,000 per trip. it uses a gallon of oil every 300-500 miles,my foot stays pegged to the floor most of the time,i never let it idle for more than a couple minutes, i have a fast idle switch, my emergy stop flap is in the right position i only stay in climates that are warm . It doesnt stop smoking and i get pulled over by police,& people flipping me the bird all the time because its smokin so bad. The problem is after running it for many miles i then park somewhere for months and i can't start it till i am leaving or the fire dept shows up & they kick me out of the park.One mechanic told me it could be cracked rings in just one cylinder. Another told me that its too much smoke for just one cylinder & that sitting for a while can get them stuck & to try sraying something in them to try & free them up. Has anyone ever had a similar experience?. busnutphil | ||
| TWO DOGS Rating: N/A |
have the rack run | ||
| Brian (Bigbusguy)
Rating: N/A |
Hay busnuts, If its using that much oil and not leaking Its time for some motor work .Your using the right oil and the preivios owner did also? Sounds like some rings are shot. I heard of people just repairing the bad CYL(s) if the rest of the moter is fine . I guess they do a compression test and repair the bad cyl and leave the rest. It would be a very cheep way to fix the problem. Brian 4905 Klamath Falls Oregon | ||
| jimmci9 #2 Rating: N/A |
pull the air box covers and look at the condition of the rings..... | ||
| busnutphil Rating: N/A |
what's an airbox cover and how do you remove them to see the rings?. Has anyone had stuck rings, and freed them up?. | ||
| jimmci9 #2 Rating: N/A |
airbox covers are side-plate covers on the side of the engine block that over up castng/acess holes in the block that extend into the cylinder/liner area.... there are 3 on each side of a v-8 block...(1 double, 2 singles) and 6 on each side of a 6-71 inline block.... on the transverse mounted 671's in the gm coaches, the blower covers up the 4 middle 1's... so you only see 2 on that side... 1 right behind the governor drive/fuel transfer drive and another right past the blower, just before the flywheel housing....kinda difficult to see....the other side of the engine has better acess, but with dual mufflers and a bus rear bulkhead in the way, its difficult to get to them....as far as freeing up rings????.. good luck... probably not going to happen.......after i remove the air box covers to check/look for worn/broken rings, coolant in the cylinder.. i also use a borescope to look at the injector tip and exhaust valves.... when you look in the air box, you'll see the clyinder liner with air-passage holes...inside the liner, you'll see the piston, move the piston up and down by rolling the engine over and you can look for broken/stuck rings, scuffed/galed piston... move the piston down past the holes in the liner and you can see the inside of the liner, the exhaust valse, and the bottom of the head, the injector tip... | ||
| TWODOGS (Twodogs)
Rating: N/A |
I just LOVE the way a diesel engine is built....love wet sleeve engines ! ! |
