Author Topic: Smoking. Cracked ring...??? What to do  (Read 158745 times)

Offline thejumpsuitman

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Smoking. Cracked ring...??? What to do
« on: February 24, 2011, 10:08:14 AM »
W.W. Williams just called me back.  They had their Sr. mechanic run the rack again.  They say it is now running smoothly, but smoking badly on acceleration out of the right side.  They are not interested in getting into it any further, saying I would be better with a new updated engine than to spend $13,000+ on a rebuild.  Their opinion is is smoking and has lost power because it has a cracked piston ring.  Mercy!

What do you guys think this means for me?  I think their standpoint is that it wouldn't be worth fixing that old engine, but obviously I am not a fleet and am not going to be driving 80,000 miles a year.  How big and expensive of a job is it to replace the piston ring and keep chugging? 

Marc
1986 Blue Bird Wanderlodge PT-40
DD 8V92TA, Allison HT748
Albemarle, NC

Offline NeoplanAN440

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Re: Smoking. Cracked ring...??? What to do
« Reply #1 on: February 24, 2011, 10:42:24 AM »
i think your best bet is to get of of their shop as fast as you can!!!

dont wanna say something wrong, but that all sounds like they dont know what they do.and they go a lot of shortcuts.

a cracked ring should be easy to see through the air box. also should have shown at compression test, if it is that bad that the engine smokes allready.
i would have left allready, and at least now .
they let you drive away first, and now they have to run the rack again to get it!! ????
what did they do first ???

i think somebody has to start over.
what happened to the injector.
did parts get into the combustion chamber.
are the valves good
compression test
rings inspected through air box

if its only a ring ,maybe a liner, still doesnt make up for a complete rebuild!!!!

just be carefull, it all sounds like they dont wanna work on a bus or even two stroke.



Offline NeoplanAN440

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Re: Smoking. Cracked ring...??? What to do
« Reply #2 on: February 24, 2011, 10:47:26 AM »
what color smoke ??  white or blue ???


Offline thejumpsuitman

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Re: Smoking. Cracked ring...??? What to do
« Reply #3 on: February 24, 2011, 10:49:11 AM »
I am at a disadvantage for lack of knowledge, but it doesn't strike me as a lost cause either.  I am going to drive it home and check with Gene Russell.
1986 Blue Bird Wanderlodge PT-40
DD 8V92TA, Allison HT748
Albemarle, NC

Offline thejumpsuitman

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Re: Smoking. Cracked ring...??? What to do
« Reply #4 on: February 24, 2011, 10:49:55 AM »
what color smoke ??  white or blue ???



White smoke under acceleration.
1986 Blue Bird Wanderlodge PT-40
DD 8V92TA, Allison HT748
Albemarle, NC

Offline NeoplanAN440

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Re: Smoking. Cracked ring...??? What to do
« Reply #5 on: February 24, 2011, 11:06:38 AM »
white smoke , is unburned diesel fuel.

it can come from low compression (cracked ring), or poor spray pattern and late timing of injector.
cracked ring makes no sense to me,that its running good in idle !!??

rings and liner can be checked through air box.
running the engine without exhaust manifold will also help pinpoint the trouble cylinder.
if not maybe the whole bank is still not running right timed.

thats just me
i wouldnt drive to far without having a second opinion.
not to hurt the engine , only because its still adjusted wrong.
if its really a broken ring , then its poker to drag her home.
its all about what will it cost to repair at place or what will go bad trying to drive home.


Offline thomasinnv

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Re: Smoking. Cracked ring...??? What to do
« Reply #6 on: February 24, 2011, 11:17:32 AM »
this may be overlooking the obvious but...as was already said white smoke is unburnt fuel.  Did they run it down the road to get it up to operating temp?  if they just throttled it while sitting in the shop it is not warmed up and white smoke while cold is not unusual.  make sure it's warmed up before worrying about any smoke.  run it down the road a few miles, get it up to op temp and see if the smoke clears.  these 2 strokes don't like to run cold, almost as much as they don't like to run hot.  IMHO & FWIW
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Offline Highway Yacht

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Re: Smoking. Cracked ring...??? What to do
« Reply #7 on: February 24, 2011, 11:36:04 AM »
this may be overlooking the obvious but...as was already said white smoke is unburnt fuel.  Did they run it down the road to get it up to operating temp?  if they just throttled it while sitting in the shop it is not warmed up and white smoke while cold is not unusual.  make sure it's warmed up before worrying about any smoke.  run it down the road a few miles, get it up to op temp and see if the smoke clears.  these 2 strokes don't like to run cold, almost as much as they don't like to run hot.  IMHO & FWIW

My old RTS use to smoke (white) like crazy on acceleration after it had been idled but it would clear up very quickly like a couple miles. It also didn't smoke at idle...just under hard accelerations. I had been told that my problem was it was either loading up from the idling or I had an injector that was squirting instead of spraying. I was told to pull the manifold off and crank it to see if one of the cylinders were smoking anymore than the others. They said that would pinpoint the cylinder causing the trouble.
« Last Edit: February 24, 2011, 11:38:03 AM by Highway Yacht »
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Offline chart1

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Re: Smoking. Cracked ring...??? What to do
« Reply #8 on: February 24, 2011, 11:37:50 AM »
I agree they did not do there diagnostics. A compression test would have indicated the problem. The bad news now is that new fuel injector might not be to new by the time you get home if those cracked rings are coming apart and exiting through the combustion chamber. If need to be, I have a brand new set of pistons and liners for 8v71 that I could let you have for 800.00 which is half price. A rebuild gasket set is 130.00 and main bearings 50.00 and rod bearings 50.00.  All you need is someone that knows 2 stroke detroits to do the labor.
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Offline papatony

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Re: Smoking. Cracked ring...??? What to do
« Reply #9 on: February 24, 2011, 12:05:08 PM »
    There is another way to check without taking the exhaust off. crank it up and get a pot holder check the manifolds beside the cylinder. for heat if you have a large deference in the temp. that will be the bad cylinder.  if all are about the same that's not your problem. It is hard to find any body that really knows 8v71  most have retired or dead. check around until you find one.  One all knowing mechanics cost me a total rebuild he didn't know half as much as he thought.

Offline thejumpsuitman

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Re: Smoking. Cracked ring...??? What to do
« Reply #10 on: February 24, 2011, 12:06:14 PM »
I just picked up the bus.  The smoke is more blueish according to my friend who followed me.  It looked like white from the mirrors, but that's 40 feet back.

The engine is running smoothly now and seems to have a little more power.  They have cracked ring at the top of their list of possibilities.  

I am 400 miles from home and have no other place to take it.  If I could damage the engine further, I will find somebody around here, at least within 100 miles or so who can fix it and just go home until it's fixed.



1986 Blue Bird Wanderlodge PT-40
DD 8V92TA, Allison HT748
Albemarle, NC

Offline thejumpsuitman

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Re: Smoking. Cracked ring...??? What to do
« Reply #11 on: February 24, 2011, 12:14:21 PM »
I agree they did not do there diagnostics. A compression test would have indicated the problem. The bad news now is that new fuel injector might not be to new by the time you get home if those cracked rings are coming apart and exiting through the combustion chamber. If need to be, I have a brand new set of pistons and liners for 8v71 that I could let you have for 800.00 which is half price. A rebuild gasket set is 130.00 and main bearings 50.00 and rod bearings 50.00.  All you need is someone that knows 2 stroke detroits to do the labor.
309-453-0963

You are right, they did NOT do a compression check, just replaced the injector to see if that worked.  I assumed a compression check was standard procedure, but apparently not. 

That is a generous offer on parts.  I will keep that in mind. 

Marc
1986 Blue Bird Wanderlodge PT-40
DD 8V92TA, Allison HT748
Albemarle, NC

Offline uncle ned

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Re: Smoking. Cracked ring...??? What to do
« Reply #12 on: February 24, 2011, 12:32:02 PM »


David's caoch   828-874-6105

russells diesel  828-863-2102

Call either one   you will not regret it.  every mile closer to them will save you dollars.


uncle ned
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Offline thejumpsuitman

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Re: Smoking. Cracked ring...??? What to do
« Reply #13 on: February 24, 2011, 12:43:29 PM »
Thanks Uncle Ned,

I just spoke with Gene.  He said it was probably a valve or a ring and to go ahead and drive it.  So that is my plan.  Drive it straight to him.
1986 Blue Bird Wanderlodge PT-40
DD 8V92TA, Allison HT748
Albemarle, NC

Offline Barn Owl

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Re: Smoking. Cracked ring...??? What to do
« Reply #14 on: February 24, 2011, 12:56:46 PM »
Quote
There is another way to check without taking the exhaust off. crank it up and get a pot holder check the manifolds beside the cylinder. for heat if you have a large deference in the temp.

Good advice, but I would use an inexpensive temperature gun instead of my hand.

Quote
go ahead and drive it.

My mechanic claims he drove a 8v71 across country after breaking a piston and having the rod flop all around. He has more war stories like that one and believes they are one of the toughest engines ever made. Overheating them are one of the few weaknesses that I know of.
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