Workhorse GM8.1L engine problems

I can only think of one other report of a failed 8.1L, and you've had two go. What colossal bad luck! That ought to be a 200,000 mile engine.

The originator of the thread had 2, I had one, and have heard of several others with self destructing pistons. You'd notice them more if you had one.  I have not heard of 200,000 miles on that engine. 

I put one in a race car that had 250,000 miles. It ran great, burned a bit of oil and is still living a happy life at or near the rev limiter on any given sunday somewhere in the american desert. Great engines but had their share of growing pains.

Wayne

Like the 454 before it, the 8.1 is really only a truck engine, (1/2, 3/4, and 1 ton).
They do a pretty good job in these MH's. 37 and 38 feet is really pushing it. GVWR
of what, 26k-30k#'s? And some of them want to pull grades at 40-45 mph.
Time for a DP.
J

IMO, the 496  is much better suited to be in a muscle car than a MH.  Especially out here in CO.  All the gassers are like a chain saw engines crossing the Rockies @ 4 or 5000 RPM and 25 to 35 MPH. Poor things.
Oh well, the new gassers may be obsolete soon. If they don't figure out a way to put a turbo charged diesel in even the entry level coaches, they'll be selling a lot less MHs

Some time ago I read a post by a representive of Redlands (A RV service facility)

He spoke of having half a dozen 8.1 L's come in in a very short time with piston failures, all identical failures.  3 had the Ultra Power upgrade (Which Redlands sells and installs) and 3 were Stock.

Workhorse covered the 3 stock ones but said the UP caused the other 3

But.... All six had identical damage/failure.

Myself....... My rig runs fine, so far that is.

I have a 2003 35' SOuthwind on a Workhorse Chassis with the Allison 5 or 6 speed. On both legs of my trip, after about a day and a half of smooth driving, it just seemed to run out of fuel. (plenty in the tank) It reminded me of vapor lock. Through experimentation, I found that turning off ignition and starting again cleared problem for a while. After resting overnite, problem did not reappear the third day. Both legs were only 3 days in length. No check engine light ever appeared and GM dealer found no codes stored in the computer. I had them replace the fuel filter before the second leg of the trip and the problem still cropped up late in the second day. Does anyone have any ideas? The unit only has about 17000 miles on it.

You have a clogged fuel filter which is intermittently choking off the fuel delivery. Not surprising in an '03, which has probably never had it changed.  It's inline, probably over the right side frame rail and fairly near the engine. rear.

You have a 5 speed Allsion in the '03.

I changed the fuel filter before starting the return trip and it still happened? Can it be a problem with Fuel filler neck or cap losing pressure?

cfodell43 said:

I changed the fuel filter before starting the return trip and it still happened? Can it be a problem with Fuel filler neck or cap losing pressure?

Click to expand...

Not likely.  The fuel system  is "sealed" to prevent excessive evaporation, but it isn't "pressurized" to force the fuel to the engine. 

Your chassis fuel filter is in the driver's side frame rail just aft of the rear axle.  If the inline filter is new,  that should not be the problem, but maybe the one you got is defective.  Since they only cost ~ $10.00 you could change the filter again to see if that eliminates the problem. 

In your OP you stated it happens "late in the day" and I'm wondering if you may be getting low on fuel (not out).  FYI,  on your model chassis the excess fuel returns to the tank AFTER the engine, unlike the newer units which return excess fuel to the tank directly from the filter.  Your earlier model fuel system allows heated fuel to return to tank and the return line is very near to the pump intake.  As the total quantity of gas in the tank gets lower, the hotter all of it becomes.  This is why I choose to not let mine get much below a half tank before refilling.  It is "possible" that your pump becomes weaker as the fuel gets hotter, causing the pump to run hotter.  Yes, the fuel is actually a cooling medium for the pump.

You need to have the pressure at the engine fuel rail tested ( I think "normal" is around 55-60 PSI )  and they should do that during a test drive, not just idleing in the shop.  If the pressure test indicates a new pump is needed you are looking at at least $500.00-750.00 for the pump and labor to drop the tank and R&R the pump, so I hope that is not the case at only 17,000 miles.

If the pump checks OK, then start checking the sensors which send signals to the ECM which controls how well the engine runs.  The most common suspects are the MAF (behind the air filter box) and each of the O2 sensors in the exhaust pipes.  I'm sure there are other sensors that "may" be suspect, but I'd start with those.  Good luck resolving this troublesome issue.  Ed 

Back to topic, I just had my second cam or valve train failure on my 8.1,  in my 26' Sightseer. First cam went flat at 10k and was replace by a GM authorized repair shop at no cost to me. Last week I had #7 intake valve start rattling, the same as last failure. I don't know yet what the diagnoses is, but I expect the same, only now I am out of warranty. Only 22K miles but it is a 2008. It is always Dealer serviced according to the  manual. My Coach only weighs 17,000 lbs. Certainly not an overload for this engine. I loved my V-10 in my last 24' coach. I nearly bought it again, but when we found this Sightseer, we like the coach and thought the Vortec 8100 would be fine. Mileage rarely gets better than 7+ MPG. Ford V-10 got better with what seemed about the same power. Hard to tell. This Coach has a high drag ratio.
No excuse for this second failure. It will be hard to get me into another 8.1.
It does not appear to be a continuation of any kind with warranty help. It seems like the same problem as before.

Not positive on your year but most all 8.1's I have seen use a roller cam and your not going to flatten one of thoughs, but even so a flat cam is all most always from contaminated oil or the wrong API service oil being used.

I believe it does. I can only go by what the repair shop says. If a Roller Cam goes flat it is usually due to a broken lifter roller.
I was 1000 miles from home and a Local authorized dealer was too busy to help me for a week. I needed to get home. So I pulled the Valve Covers and found #7 intake loose. All others were fine. I shimmed the rocker arm down, with a washer, to get a zero clearance. Drove another 300 miles and did it again. Total shims/washers equaled about .030".  This lasted me 700 miles to get home. It is not in a shop yet. All I can say at this time is the threaded Rocker Stud in in tight. There is no damage on the rocker, valve or push rod. What ever changed in out of sight. I was a mechanic in the 60's and 70's and I am not afraid to tackle my own problems, but I am limited on what I can do, on the road. Good news, I made it home.
The engine is not missing. It is running smooth with full power. I never revved above 3000 rpm all the way home. Down shifted by hand with slack throttle. Most of the miles were at 2200-2700 rpm. Did what I had to do,  to save it.
Last oil change was at Camping World. It appears they used bulk oil. Can't tell if it is Syn, but would hope so. Maybe not. I trusted them.

A blown head gasket is usually caused by loss of coolant or other overheating issues . Was a new thermostat installed when engine was originally replaced ? If the thermostat was not replaced ,I would be in contact with the dealer that did the work. The intake manifold is reused when the new engine is assembled for installation if one did not come with new engine. Was that intake checked for good sealing surfaces at cylinder heads? I would check the parts list that was printed on your receipt to see what parts were replaced. Was coolant level and all other fluids checked prior to trip. If no external leaks were found then it would be a good idea to contact GM area service representative regarding a defective unit or possible installation issues.

This has been an interesting thread.  Very informative.  After reading a few posts, I was thinking my next coach, if I don't buy a diesel will be an 8.1.  After reading the entire thread, I'm not so sure.  I am sure about one thing however.  If you own a motorhome and you're not mechanically inclined with a lot of experience and a few extra points between the ears, you'd better have a sizable bank account.   

Most of this thread is very old!  There are bound to be engine failures for every manufacture.  If I had 2 cam shaft failures that close together I'd be looking for the reason why. Oils have change dramatically in the last few years. Some of them no longer will work in an older engines with out an additive. I know a few guys that have had some trouble with classic cars too.

Two things to remember:
1: It is has been well and truly said that every company, no matter how good, will turn out the occasional lemon, and no matter how bad the occasional golden nuggt.

and

2: The owners of the lemons tend to shout a lot more and a lot louder than the happy customr with the hunk of gold.

I would not shout if GM would honor the problem. When manufactures give a 100,000 mile warranty and restrict it to 3 years, it is very deceptive. How many MH owners can drive 100K in 3 years. 90 miles per day is more like commuting to work. That is not why we retire.
If you are not a full-timer, it is impossible to reach those miles that fast, and a 26' MH would never make it as a Full Time Home. An 8.1 engine should be over-kill in a 26' Sightseer. It should last forever. Just my two cents. My last 5 commute vehicles ran 100K-120K in five years use, with nearly no repairs other than normal maintenance. And when traded in at those miles showed little sign of being used up. I don't think I am shouting about a false issue.

I have a 2001 Winne sunrise with a 8.1 GMC. The starter went out and the new one I purchased dose not match up. The starter gear will not engage the flywheel. As if the housing is too short. Has anyone seen this type of problem?

Thank you Gary

how do I post a question....been a member awhile and can not find a post it place