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Author Topic: 8V92 leaking oil  (Read 7191 times)
paul102a3
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« on: August 02, 2009, 02:17:40 PM »

My 8V92 DDEC II has started to leak oil from the front crankshaft seal and possibly the rear seal as well. In addition, there is oil leaking from the alternator both at the mounting flange and the wire connection end.

A little history is in order. There are 215,862 total miles on the coach since new in 1988. In 2003 and 188,000 miles the engine and transmission were pulled to repair a suspect transmission. (it turned out to be a shorted wire causing the shifting problems). While the drive train was out, the front and rear main seals were replaced as was the alternator to block gasket. The oil leaks supposedly were not big but since the package was out of the bus, the PO decided to replace the main seals and gasket.

According to the PO, there have been no oil leaks since those repairs were completed in 2003. Since my purchase of the bus this spring, a slight oil leak started at the front main seal (I say front but I really mean the seal located behind the harmonic balancer). I noticed it a few weeks ago when we did a 100 plus mile run with many of those miles between 70 and 75 MPH. It amounted to a few drops collected at the rear motor mount. The next few runs were mostly local and there was no additional oil present so I chalked it up to the high speed run.

Two days ago, I took the bus on a 271 mile exercise run mostly on interstates and maintained between 65 and 70 MPH.

When I pulled into my driveway, the back of the bus was covered in a fine mist of oil. Looking under the bus today, the bottom of the oil pan was covered with oil as was the rear motor mount. There were quite a few big drops just waiting for gravity to take its course and stain my driveway.

Up until this episode the oil level has not changed in the 1380 miles since the oil and filter were replaced a few months ago. After this run on Friday, the oil level is halfway between the marks on the dip stick.

As far as the rear seal is concerned, I canít tell if there is oil coming from the seal or if it is the alternator leaking and dripping or a combination of the two.

My questions are; what could have caused the seals to fail and does the motor need to be pulled to change these seals? How hard is it to pull the alternator and have new seals put in it? There doesnít seem like there is much room to pull the alternator without pulling the air filter and related plumbing. The bus is a 102A3.

Any thought or advice would be appreciated.

Paul
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2001 Prevost XL II
buswarrior
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« Reply #1 on: August 02, 2009, 03:15:14 PM »

First, the back of the bus looks lots worse than the amount of oil it takes to make it look that way.

In other words, a very small amount of oil goes a long way to covering you in dirt. I have had coaches with oil appearing to run down the back only show the stick down a quarter of the way to add from full, where it was in the AM before it went wrong, so about one quart. It looked like GALLONS.

So, don't be too worried because of the appearance.

Second, what oil is in the engine? Multi-grade leaks much better than 40 wt.

Third, forget the crank seals until everything else has been dealt with.

Fourth, yes, the alternator needs to see a doctor and can be re-sealed.

happy coaching!
buswarrior

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expressbus
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« Reply #2 on: August 02, 2009, 04:52:41 PM »

Paul,

There is another source for a leak at the rear of the 8V92. There is a little o-ring seal for the power steering pump that has a bad habit of going out about every 2-3 years. It is the dickens to get at. I found a local tour bus garage with a really skinny and flexible mechanic to make the repair. No more leaks so far. Check the fluid level in the power steering reservoir. If it is low to really low the leak in the rear could be that pesky little o-ring. I think the o-ring costs $0.75. I bought a spare to carry with me just in case I am in transit the next time it fail. Priceless!
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Will Garner, Jr
Southern Pines, NC
1991 Prevost Conversion by Country Coach
paul102a3
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« Reply #3 on: August 02, 2009, 06:38:14 PM »

The oil is 40 wt which is what has been used all along. My concern is the sudden increase in oil loss from the engine. My best guess is it all went bad somewhere in the last 140 miles of my trip.

Is there a standard amount of oil between the high and low marks on the dip stick? I know my boat is 1 quart between the marks but is it the same on an 8V92?

I will check the power steering reservoir and pump but I believe my power steering is filled with ATF. I have not verified that it is ATF but there is a note written on the inside of the rear door stating this fact. I guess now is a good time to verify if it is ATF or oil.

Thanks,

Paul
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luvrbus
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« Reply #4 on: August 02, 2009, 07:03:54 PM »

Paul the marks are different depending on the oil pan my 8v82 in the Eagle is 1 gal between the full and low marks   

good luck
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buswarrior
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« Reply #5 on: August 02, 2009, 07:16:04 PM »

Correction to your trouble shooting thinking:

Don't be naming the engine, you'll miss something important.

You are loosing enough oil to be wearing it on the back of the coach.

What kind of oil, still remains to be seen, as a half gallon in 1300 odd miles could just as easily gone out via the exhaust.

Out of the engine, or out of anywhere else in that lubrication system.

Tranny and power steering look the same on the back of the coach mixed with dirt.

usually, it is one gallon between add and full on a bus dipstick.

Put this in perspective, as long as there is oil in all the reservoirs, the machine is not harmed.

Every little drip under the coach will be worn on the back due to the vortex of air curling up the back while going down the road. A nice early warning system, but not a cause for alarm.

happy coaching!
buswarrior

happy coaching!
buswarrior
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« Reply #6 on: August 02, 2009, 07:40:03 PM »

Assuming the correct dipstick?
Where is the oil level on the dipstick when the engine is cold?   
Checking and adjusting the oil level on a hot engine will result in overfilling...
The engine may have a lot of wear and at the speeds you're driving, it's blowing oil out wherever it can.
The fact that the seals were replaced is probably an indication that the problem onset isn't as new as you may think. 
One other tidbit of information is that the seals must be "rotation" correct (RH in your bus), and they are Teflon seals.  Teflon seals are installed dry.  A good many old DD mechanics have a difficult time with the "dry" concept.   Lubed Teflon seals won't 'seat.'   Failure to follow proper intallation technique could cause premature failure of the seals.  And add another layer for failure, the seals are matched to the wear rings.   Perhaps the wear rings were not replaced, or maybe the wrong dia seals were used.
Oil leaking in small puddles from the bottom of the bell housing once the coach is parked is a pretty good sign of a rear main leak.   It collects in the bell housing and oozes out when parked.
Check the oil level cold, make sure it's between the full and low marks.  Don't add oil if it's between these marks.   Take the bus out for a 60 MPH ride.  If the leak issue subsides considerably at lower speeds, blowback in the engine may be pressurizing the crankcase.   
You may want to check your airbox drains and valve cover road draft tubes and filter.  Make sure that they are not stopped up by bees or crud. 
Does the engine smoke when cold?  Smoke when driving at highway speeds?
The oil use you are describing, halfway down the dipstick from full in 270 miles, is abnormal oil use. 
There is no harm in allowing the oil level to fall off to the lower levels on the dipstick.   I wouldn't let it drop below the 'add' mark, but some well-worn two strokes blow out the first couple of quarts when full.   
Checking the engine oil level cold will give an accurate oil level.   If it's overfilled, it'll blow the extra oil out.
Alternators don't typically leak.  A 50dn adaptor requires centering with a special tool before installing the alternator.  You might have a series of screwups by a poor mechanic.   However, since all the same points seem to be leaking after repairs were made, you might have an engine problem too.   
A good many extremely low mileage coaches seem to have issues due to lack of use. 

HTH, JR

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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.Ē

Ayn Rand
paul102a3
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« Reply #7 on: August 03, 2009, 03:56:02 AM »

Buswarrier and JR, I always try to check the oil under the same circumstances, flat surface, engine cold, etc, and up till now, the oil level has been at the full mark each time.

I will call the shop today and try to verify oil brand and viscosity. The same guy has changed the oil and filters for the past 6 years and the invoice states 34 qts oil, 40W but we all make mistakes and who knows, he may have substituted multigrade. If multigrade were substituted, would it take a while for things to go wrong?

For 1380 miles, there has been no change to the oil level, no oil misting on the back of the bus and no significant drips in my driveway. After this last trip, I left a 10 inch long oil run on my driveway as I was backing up the slight incline of my driveway.

The engine does not produce oil related smoke when cold or hot, just a puff of black smoke when starting out from a stop light. I ran the bus several times yesterday in the driveway with no visible smoke at startup or when it was hot.

I donít know if the replacement seals were Teflon but I will find out. I have the invoice with the part numbers so it should be easy to call and ask. There is part number listed on the invoice for both a sleeve and a crank spacer so I assume that may be the wear ring you refer to???

I am not getting any pooling of oil under the bell housing at this time, just a lot of oil covering the oil pan.

How does one check the airbox drains and valve cover road draft tubes and filter? We have a lot of mud daubers here and I have found several drains clogged with their nests, so that may be a possibility.

JR, if I understand correctly, I could pull the alternator, have it resealed but I would need an alignment tool to reinstall it???

FWIW, prior to my purchasing the bus, I took it to DD for an overall engine and trans inspection, oil and coolant samples were taken and were clean and I had them run the bus on their chassis dyno. I also took it to an independent shop and had them go over the bus from front to back. Both shops commented at how clean the drivetrain was so this oil leak situation seems to be sudden onset.

Thanks,

Paul
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paul102a3
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« Reply #8 on: August 03, 2009, 03:05:13 PM »

After several hours of crawling under the bus today, I am 99% sure the front main seal is the primary source of my oil leak. There is also a small amount of oil leaking somewhere around the rear of the engine but I canít determine if it the alternator, the rear seal or a little of both.

I called DD and they are quoting 4-5 hours to replace the front seal and 22-23 hours if the rear seal needs to be replaced. Do these labor hours seem reasonable? The reason I ask is the PO was charged 37 hours to do the same work at ABC bus here in Florida.

Talking with the DD service manager, he feels that the seals that were replaced 6 years and 35,000 miles ago have dried out from sitting and now that the bus is being run a fair amount, they are just passing oil.

My thoughts are to replace the front main seal, repair the oil leak from the alternator, and see what happens with the rear seal. Does this make sense?

I did check the power steering reservoir and there is no loss of fluid but thanks for the tip.

Thanks,

Paul
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« Reply #9 on: August 03, 2009, 07:26:34 PM »

Sounds like a plan.  The rear main would be the last thing I'd take potshots at.   
You can remove the alternator from the adaptor without any special proceedures.   
The adaptor is what has critical alignment.   Unless the adaptor gasket is leaking, don't remove the adaptor.   Just pull the alternator off of the adaptor..."just" is a relative term. 
There are various methods to pull the alternator.  You can remove the air cleaner and pick it out with a cherry picker, or if you know someone that has more muscles than good sense, it can be manhandled out thru the floor hatch.   It is nasty, very heavy and sorta fragile.  Be careful with the alternator project if you're not familiar with such things.    Make sure that the battery mains are off and the alternator is de-powered before removing cables. 
If you plan to pull the powertrain, clearly that would be the time to work with the alternator. 
The alternator is a PITA to remove when the engine is installed in the bus. 
You'll have to gain access thru the hatches located where a bed is usually installed...? 
The seals may be suffering from sitting.   May have been improperly installed.  Hard to screw up both of them?
The time quoted is at the extreme end of 'reasonable' IMHO.   
They are probably quoting two mechanics (one mechanic and one helper) for about 2 days worth of work.
The engine and transmission can be removed in a few hours.  Once the cradle is out, another 2-4 hours should install the seal and wear ring.  The problems begin when special tools for two strokes aren't available, and such things as removing wear rings can be a hangup.  However, removal of the bell housing is not required to replace a rear main and wear ring.  The wear ring is a PITA and must be removed without damaging the crank or bell housing.   They are covering their butts. 
They may be using truck flat rates too.  In this repair, a bus is a much quicker operation than truck.  One of the rare easier jobs.  No accessories must be removed to pull a cradle from an MCI.  Even the transmission oil cooler remains connected to the transmission, and the power steering lines have quick disconnects located at the bulkhead.   
I'd steam clean the engine and then drive it enough to see where the oil is coming from for sure. 
It would be a bad situation to have all that work done and still have a leak.   The mechanic will not be able to ID a bad rear main seal unless it's displaces or damaged from poor installation during prior service.
Regarding the airbox drains....you may have a catch-can under the rear of the engine with two small hoses attached to it.  The drain hoses exit about center on each side beneath the exhaust manifolds.  You'll see the hoses and a check valve.   
When the bus is idling, both hoses should drop a small amount of oily gas.  If they do this, they are clear.   If they are dry, the hoses should be clean, replaced, or whatever it takes to get them cleared.  The check valves are in the hoses and same applies.   
If you are not dripping oil from the hole in the bottom of the bell housing...you may not have a bad rear main seal.  The oil could be coming from a cracked line, head gaskets...ad infinitum.   Cleaning the engine and evaluation should resolve what's leaking.   
My rear main seal failed at about 180K.  It wasn't difficult to see where the oil was coming from.
Leaking from both the open unused motor mount holes in the bell housing (middle sides of bell housing) and the drain hole in the bottom of the bell housing.   
You might want to check that the bell housing drain isn't plugged with a pipe plug.  It's threaded and someone may have decided to plug the hole.  Then oil would run out the sides of the bell housing and ooze from all over the rear of the engine.  This would not cause the alternator to leak.  The alternator is driven from inside the gearcase in front of the bell housing. 
If oil isn't running out of the bell housing drain, the rear main seal is likely not the proximate cause of your problem. 
Odd that both front and rear crank seals have failed suddenly at the same time?   Pull one of the valve cover breathers off the engine and see if you get a 'rush' of air and oil vapors.   They are easy to remove. 
Make sure that you have the correct oil in the engine.   I'm not sure that you've driven enough for multiV to screw anything up, but old DDs don't work well on 15W40.    That's all most mechanics know about these days.   They swear it's best.  But, it won't work in 2 strokes. 
BTW, black smoke isn't indicative of a problem.  That's due to overfueling at startoff.  That's one of the reasons electronic engine control systems were developed. 
Good luck, JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.Ē

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« Reply #10 on: August 03, 2009, 07:31:40 PM »

One more thing...the alternator oil inlet line has a flow limiting orifice (small jet) that may be missing. 
I would guess that if it wasn't in place, the high oil flow might cause the alternator to leak. 

JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.Ē

Ayn Rand
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« Reply #11 on: August 03, 2009, 07:51:58 PM »

Paul, I would clean the area good and check the oil pan a DDEC uses a special gasket and bolts to prevent the pan from being over tighten and they do come loose and will have the same appearance as a seal leaking   

good luck
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paul102a3
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« Reply #12 on: August 03, 2009, 08:24:01 PM »

JR,

Thanks for all your input. Both airbox drains function as you describe so that is good news to me. The threaded hole in the bottom of the bell housing is clear and is not dripping oil so maybe the rear seal is fine.

I am pretty confident that there is straight 40W in the engine. The mechanic that did the oil & filter change went to great lengths to tell me to never use multi grade oils and to only use 40W. He could have grabbed the multi grade hose but I really doubt it.

I did take a long look at the alternator and how I would remove it if I have to and you are right, it looks to be a bear to get out. I will look at the bed and see how hard it will be to open it up and gain access that way.

I agree, it is odd that both seals might fail at the same time however, if the front seal has failed due to drying/sitting, logic suggests the same might happen to the rear seal.

The engine, trans and surrounding areas are now clean of all oil and dirt (what a mess). I was planing to do some local, around town driving in the morning and see if it leaks under city conditions. If it stays dry, I will then run the interstate and verify the location of the leaks.

Thanks for your help and I'll keep you posted as to the outcome.

Paul
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paul102a3
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« Reply #13 on: August 03, 2009, 08:28:12 PM »

Luvrbus,

Thanks for the oil pan tip. I will check the bolts before I head out tomorrow. Do the bolts need to be torqued?

Paul
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buswarrior
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« Reply #14 on: August 04, 2009, 12:29:16 AM »

Assembling a collection of lumber in order to make a ramp of sorts to roll/crash land the alternator out via the side engine access door will probably be easier. Pay CLOSE attention to the cabling and connectors that are in harms way on the rear junction box and don't snap any of them off!

To re-install, pushing it up the lumber ramp and your helper working the fasteners from above will work better than trying to hang it from above and your poor sod of a helper waiting for it to be dropped and crush fingers.

It ain't pretty, lots of cursing and lots of lumber bits to prop, pry and heave. An old long fan belt used as a sling from above to help it all along might be thrown into the mix.

85 pounds of electrical love.

happy coaching!
buswarrior
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