Opinions on GM 6.5

[orange150]

I know the general sentiment of them being a dog etc., but are they really that bad to live with? Been keeping my eye on GMT400 2500 burbs, would prefer the 454 but I've seen a few clean 6.5s pop up somewhat close to me that I'm curious if I should really pass them up if they're clean enough.

The only thing I really know about them is the PDM needs to be relocated if not already done.

 

[lbyota85]

 

[orange150]

A lot of hot takes in that video.

I also didn't hear anything necessarily bad with the 6.5, thanks for sharing.

 

[skyhighZJ]

FWIW we ran the dogpiss out of a turbo 6.5 in the HMMWV. Motor wise they were pretty stout. @Tacoma747 may have some insight?

 

[Tacoma747]

FWIW we ran the dogpiss out of a turbo 6.5 in the HMMWV. Motor wise they were pretty stout. @Tacoma747 may have some insight?

Well, the old non turbo 6.5 is essentially the same as a GM 6.5 of the same era I think, but the turbo variants are more similar to a VAN style 6.5, which is a completely different set of heads, intake, and turbo.

The biggest difference would likely be that all HMMWV engines are fully mechanical whereas the GM trucks and vans has a computer controlled injection system which could have issues I think. That said, I think 'fatal' issues are not a problem, just common stuff like the engine computer, maybe cracked heads or blown head gaskets??

After 2001, all HMMWVS had GEP engines, which was basically a knockoff of the GM block/heads, but with stronger/better casting materials used.

 

[Tacoma747]

And on a further note, back around. 2011 I had a job where the company used surplus government express vans with the 6.5. We had an in-house mechanic that worked on them so he knew all the common issues with them, but for can use, they had plenty of power. If you want to tow a 8,000 lbs trailer up black mountain, you are probably going to be wishing for more.

 

[BNielsen]

A little late to this, but I love mine.
It's completely stock right now outside of a relocated PMD and a 4 inch straight pipe, but I've got an HX35 and I'm searching for an intercooler to swap in.

I've also got a Vortec 454 truck, and it'll pull anything at least until the transmission acts up and shuts the fun down.

There's a ton of resources out there on 6.5s and how to build them; there is a guy on YouTube who's bread and butter is 6.5 trucks; Gingersnapscustoms is his page, covers all the basics of how to maintain and how to modify for reliable performance.