So I’ve been truck shopping and came across an Avalanche 2500 with the 8.1 big block. Does anyone have any experience with that motor. It has a lot of miles but the truck looks extremely cle
Chevrolet 8.1 big block
- Thread starter Weldin Rod
- Start date
I went back and forth on 8.1 vs. 6.0 in the search for a 2500 burb. I settled on the 6.0 because of parts availability and interchangeability with others I own, especially the jeep. Essentially I'm towing a spare drivetrain (all sensors, accessories, etc).
That being said, the 8.1 is a "better" heavy truck engine. It also should have the upgraded 4L85e behind it.
What's a lot of miles? They tend to show low oil pressure with high miles, and I read a lot about oil consumption. There's a fairly common issue something to do with intake seals that contributes to consumption.
it has 200k+ on it but it’s really clean in the photos. He has it priced a little high at 9000. KBB is less than 6000. I’m thinking I’m going to pass. 
When i moved up here i had a 8.1l in a chevy 2500HD. It was a great motor. I could pass tractor trailers with a slide in camper on the truck and pulling a jeep on the trailer. It just wouldnt go past gas stations. it was a thirsty motor. There is piston slap issues with them. I had piston slap and it was not a problem. There is a bunch of google stuff about that issue or non issue. but it just makes a good sound at start up then nothing else. i loved the truck but at that time i had to sell it off unfortunately. and i believe all the 8.1l came with the Alison transmission behind it
8.1 in the pickups got the Allison. 8.1 in Suburban/Yukon XL is 4L85E. I believe the Avalanche got the 85 as it is a chopped off SUV not a pickup, but not positive.
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So is that a bad transmission?
No, not at all. Allison is just even stronger than a 4l85 and 5 speed vs. 4 speed.