Community Forums

donr103 · 12-08-2022, 10:49 AM

Gm/Chevy made millions of these engines.. and they are very same across the generation of that yr.. or very close they are in light duty trucks and 4×4 and others.. one can find parts easily and get salvage parts easily.. it will be many yrs yet before they run out..
Good luck and keep us posted

CamJam1 · 12-10-2022, 07:20 AM

Not sure where you ģot the idea that the 8.1 is problematic. I frequently see posts on here from people with over 100k miles on theirs. Only weak areas seem to be plug wires and occasional exhaust manifold cracks. Most engine failures are from running lean, so buy a Scan Gauge and monitor fuel trims to make sure MAF sensor isn't bad or dirty. They do use a little oil-- a quart every 1,500 miles or so is not unusual-- but that's just the nature of the beast.

George Schweikle · 12-10-2022, 08:20 AM

I kinda remember GM stating the service life of the 8.1 engine in RV use was 200,000 miles.

Quote:

Originally Posted by yeloduster

I think the evidence tends to lean toward the 8.1L GM engine being a more reliable engine than the 7.4L engine. However both engines very often had the endurance to outlast the vehicle they were in....

MrMark52 · 12-10-2022, 08:57 AM

I’m a GM guy - but when we started our hunt last year for a “new to us” coach, I was looking at the Ford V10 - to move up from our cramped ‘91 Chevy 7.4l with the 4L80E.

After looking at a few coaches and reading, I came to the conclusion that the Ford V10 had 2 more cylinders worth of parts.

We ended up with the Chevy 8.1l with an Allison 5 speed - almost 38k on the clock.

I immediately changed all fluids, flushed the radiator/coolant system, flushing the Dexron in the Allison and replacing with TranSyn. Had the brake recall completed on the W22 which included a complete brake system flush, chassis lube. (Oops, I need to flush the power steering).
New 101 plugs and Magnum wires - just because.

After checking/watching Long and Short Term Fuel Trims using both a ScanGauge and my trusty FoxWell N301 - I found the LTFT’s way out of the norms. With the help of Jon at UltraRV I found a bad fuel rail dampener and MAF sensor (after cleaning it still gave bad readings).
I got rid of (sold) the ScanGauge because it didn’t record “live data” - my FoxWell does (the only thing the ScanGauge does that the FoxWell doesn’t is give transmission fluid temps).

Everything I’ve come across has said rather 8.1l is a bullet. We’ve towed our Jeep 4-door JK up thru the mountains of CO and UT without issue or signs of struggle.
I think a lot of issues with burned plug wires and cracked exhaust manifolds are the result of how the coach builders “trap” the engine under the doghouse and behind the front grille to cause hot and cold spots around the engine. Our coach - I think we got lucky in that regard - no burned wires, it runs cooler than what I would expect even when missing the rubber air dam over the radiator - even when pulling the toad, in summer, thru the hot panhandle of Texas with the dash air running.

David 70 · 12-11-2022, 02:21 PM

Well, I've gotten a lot of good responses on the matter here. I guess my concern was that I see the bad commentsnand not any good. I don't see near as many comments either way on the 7.4's so that was my worry. Of course buying anything used is a gamble no matter how closely it is checked out. One mention was of the oil usage but I've always heard that all big blocks use some no matter the manufacturer. My 7.4 uses some and I've been involved with the 454, the 466, the old 396, the 460's and theyall done the same. The one I've been looking at has the Allison 1000 transmission. I drive snowplows with the Allison in them and they stand up to that abuse they have to be good. Of course they are a whole different type but still the same manufacturer.
A friend of mine went from an8.1 to the V10 and he said it was not as good as the 8.1, less power.

herbc · 12-17-2022, 12:57 PM

I got here because my 2003 Allegro Bay 37DB 8.1 just blew up and I still have no idea why. Thankfully I was 20 miles from home. I had left home after checking oil, water, etc. and stopped for fuel. Five miles down the road it started losing power and I immediately pulled over and stopped. It was overheating and would not restart again. After getting it back home I had a mechanic pull both heads and found four valves broken and a cracked head. The mechanic nor myself have a clue as to what happened. I have owned the coach for 6 years and the engine has been excellent. I have now removed the engine and am looking for the best place to purchase a reman engine. Any suggestions appreciated. FYI we removed the engine from the top and out the drivers side door.
I also need info/part number on the radiator as I intend on replacing it as a precaution since the engine is out.
Herb

MrMark52 · 12-17-2022, 01:18 PM

An engine running fine with adequate fluids - that all the sudden starts losing power, then quits - only to find broken valves and a cracked head indicate to me that the timing chain or camshaft broke.
The cracked head, depending on how bad it was cracked, may have been from a PO overheating the engine but not so bad as to make it run that bad or pressurize the coolant system (or maybe it did?).

F4Gary · 12-17-2022, 01:26 PM

Quote:

Originally Posted by herbc

I got here because my 2003 Allegro Bay 37DB 8.1 just blew up and I still have no idea why. Thankfully I was 20 miles from home. I had left home after checking oil, water, etc. and stopped for fuel. Five miles down the road it started losing power and I immediately pulled over and stopped. It was overheating and would not restart again. After getting it back home I had a mechanic pull both heads and found four valves broken and a cracked head. The mechanic nor myself have a clue as to what happened. I have owned the coach for 6 years and the engine has been excellent. I have now removed the engine and am looking for the best place to purchase a reman engine. Any suggestions appreciated. FYI we removed the engine from the top and out the drivers side door.
I also need info/part number on the radiator as I intend on replacing it as a precaution since the engine is out.
Herb

More info. W24? P32? I think you are looking at $700-1000.

Rockwood27 · 12-17-2022, 01:51 PM

I had a 2006 Winnebago on a 2005 W22 chassis. The only problem I had was spark plug cables. I replaced them in a parking lot near the start of a 6,000 mile journey. No more problems after they were replaced. The 2005 and prior Workhorse chassis had the 5 speed Alison transmission. Starting in the 2006 chassis year, they upped the Alison to a 6 speed. My Workhorse always got about one MPG better than my friend's Ford 22K chassis with the V10 and 5 speed.

Sent from my SM-A515U using iRV2 - RV Forum mobile app

herbc · 12-18-2022, 10:12 AM

Thanks. By the time I had pulled over the engine was hot. The engine has now been removed. I will be pulling the front pulley this week to expose the timing chain and to get the engine number. I will let you know what is found. FYI only 80,000 miles on the engine and I have loved this engine. Plenty of power and took hills with the Allison 1000 transmission like a champ. Hope Tiffin will give me the engine number as well along with the radiator part number. Gonna take a while.

F4Gary · 12-18-2022, 12:21 PM

It will be a Workhorse part number. Just do an internet search with your year and type chassis (W2x or P3x).
UltraRV will have one but you might find it cheaper somewhere else.

herbc · 12-21-2022, 04:43 PM

I called Tiffin who could not help. Called Workhorse and they could only give me the OEM number. They gave me the number for the radiator also but when I checked the size fir that number it was definitely the wrong size. If I find an engine I will remove the radiator and take it to the nearest shop. I called Rydell and gave them the OEM and they gratiously spent time crossing the number only to tell me they do not have the engine. They had one on their sire for $2945. Shucks!

MrMark52 · 12-21-2022, 05:03 PM

Not sure of the design of the radiator - but if it’s got metal (brass) end caps - you might find a radiator shop to recore it for you. Had that done to our old ‘91 radiator - the shop added another row of circuit (increased depth in direction of air flow - there was room) from 3 to 4 rows, an increase of 33% capacity.
Cost was $450.00 and I got a much better radiator than if I bought a newer design.

Since you got the engine out - you might look at retrofitting the radiator out of a C3500 or similar where the 8.1 was used - maybe you can find a rebuildable one.

herbc · 12-22-2022, 08:07 AM

Thanks. I am not sure mine is bad and hope it is not but I will remove it and have it checked. My temp always came up and stayed at the same place so I am hoping that will still be the case. Slowing down on this subject until after Christmas. Things are getting busy.

Herb