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2001 GM 8.1 typical life expectancy?

SlowBoat

SlowBoat

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Location
Henagar, AL
Looking at a 2001 Chevy C3500HD 5spd former propane powered propane company service truck. The propane unit has just been removed from it. The transmission has been rebuilt about 6 months ago before the truck was replaced with a new one. Engine performs well.

The overall condition of the truck is pretty good for a 15 year old with 225,000 miles.

I'm just ignorant about the 8.1 V8. I know that running on propane makes for an extremely clean engine internally. What are the peculiarities of the 8.1 and what do I need to look for?

If the engine croaks and I convert to a 6.5L diesel, can I use the trans without a LOT of converting or would I have to find a trans from behind a 6.5 to go in it?
 
Ours has 320,000. Biggest issue is keeping the 5 speed allison in one piece. The allison is fine but ours has been out 4 times and just blew the input seal. It uses some oil but always has.

I wouldn't hesitate to buy one if it was nice and ran strong.
 
Other than using some oil, I've never heard of one wearing out. As to swapping engines, GM got that part right. They used the same pattern and setup on the newer 6.0l, 8,1l, and duramax in 2500hd+ as they did in earlier trucks. You just have to use a clutch setup for a nv4500, and you're good to go. And as to an 8.1l hurting an allison, I don't buy it. Somebody is overlooking something for that to happen.
 
Thanks for the input. The truck is priced right, so even if it turns out to be a project, it will be an affordable one. I couldn't build the base truck bed with the outriggers for the price. I would like to be able to drive it a while before I start pulling it apart though.
 
Just check the oil regularly. I had one in 03 to early 05 and it used a bit pretty regularly
 
THEFERMANATOR said:
And as to an 8.1l hurting an allison, I don't buy it. Somebody is overlooking something for that to happen.
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I never said the truck was well cared for or that the trans had a full 100% rebuild. More like a fix what's broke for as cheap as possible and keep going another year or 2.

This is the same truck that we broke the frame on right behind the front leaf spring hanger (where the gooseneck plate had been welded to the frame). We found out the bed was the only thing holding it together when we swapped beds it's fell apart.
 
not quite comparing apples to apples as my 05 hasn't even rolled 93,000 miles.

original owner, zero problems from the engine or tranny. uses 1 qt per 3,000 miles. can squeeze 12 mpg empty on the highway. normally it's around 10 mpg. working hard is about 8 mpg. don't waste money on anything but a pcm tune for any mpg or improvements unless you want to sink serious money into it. there is a lot of torque management programmed in, don't expect to light up the tires but it just keeps going and going.
 
Propane is hard on valve seat wear. Some engines don't do well requiring optional or aftermarket valve seats and others are ready to go from the factory. Some can be ordered propane ready. I am thinking the Dodge Hemi 4.7 and 5.7 in this context and have no idea on the 8.1.

With 200K miles you will always have the little things to deal with that simply wear out.
 
From what I here from the propane fleet truck guys, they love the 8.1 in the Kodiaks with direct propane injection. I have a friend that bought one of them and put a rollback bed on it and he absolutely loves it! The 3500HD that I'm looking at had an add-on dual fuel unit that has been removed and is back to just straight gas. I just dislike the aggravation of locating the propane when traveling out of state. Prefer to stay with diesel, even if I have to do the engine swap.
 
So this is in a GMT 400 C3500hd? You said 5 speed and got to thinking after rereading that you might mean an NV4500 5 SPEED as there weren't many C3500HD's with an allison and if there were they were typically an 02.
 
Propane to gas is usually the flip of a switch to go between them on computer controlled engines, at least on the ones I played with.
Run propane where you can, then if you need max power or cant get propane on the road- run gas.

6.5would bolt up inplace of an 8.1. Dashboard dealings would be the number sense, as long as you stick to a db2.
 
tanman_2006 said:
So this is in a GMT 400 C3500hd? You said 5 speed and got to thinking after rereading that you might mean an NV4500 5 SPEED as there weren't many C3500HD's with an allison and if there were they were typically an 02.
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There was never an allison put into a production GMT-400 truck. The 8.1l either got a NV4500 or the 4l85E if it got an 8.1L Same powertrain that came in the 2500 BURBS and AVALANCHES.
 
Yes, this is a GMT400 C3500HD, with the 8.1L gas engine that the propane distributor pulled the propane conversion unit off the motor switching it back to gas only. It has the 5 speed manual transmission that was rebuilt a few months ago before they started switching the crane and equipment over to their new fleet service truck. These guys typically just build the big propane delivery trucks. I was mainly interested in it for the rebuilt trans to go into my avatar chassis, but if it runs out good it might be another project truck, like I really need to add to the fleet.
 
That 8.1L is going to outpull a 6.5L any day of the week, and get better mileage than a 454 doing it. It won't get diesel mileage, but considering the size of the engine, they do pretty dang good really. The 8.1L isn't a bad engine, just likes fuel since it's a gas burner.
 
Ferm, I will have to go do some digging over at www.3500HD.com, but rumor has it some of the late C3500HDs, actually titled as 03s they were so late, actually had allisons. I have never seen one so it could be just that, a rumor, but I am not sure that someone did not post pics of one over there.
 
GM Guy said:
Ferm, I will have to go do some digging over at www.3500HD.com, but rumor has it some of the late C3500HDs, actually titled as 03s they were so late, actually had allisons. I have never seen one so it could be just that, a rumor, but I am not sure that someone did not post pics of one over there.
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Well the GM ordering guide for 02, and a VIN check on an 02 confirmed ONLY the MT1 heavy duty 4 speed 4l80e automatic as an option.
 
I've seen one with allison but they had ran the 8.1 out of oil and had a carbed engine dropped in. They said the trans never worked right after that.
 
tanman_2006 said:
I've seen one with allison but they had ran the 8.1 out of oil and had a carbed engine dropped in. They said the trans never worked right after that.
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I know on the 3500hd site several said theres had an allison in theres, a 4 speed allison. Funny thing is I'm pretty sure the 545 never made it into anything new past 98, and all of there electronically shifted trannies are 5 speeds or more. It's right there with if you go to a dealer, many of there guys in the back say the 4l80e is just like an allison. I'd have to see one to believe it as ALL the official literature says MT1/4l80e.
 
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