This will be our first Hummer. I bought it knowing it had issues, but even if the motor was bad, I got it for very little money, so an investment into a rebuild/motor replacement would not be to big a deal. Sure enough cylinder 1 had bad rings, (reads 35 psi, and 200 when wet compression tested). So, if this motor is salvageable, should I rebuild, or upgrade to an LH8 Vortex 5.3? Fyi, this is a project/spare vehicle, so being down for a while is no biggie.

Thanks all!

 

MOVED to the H3 section where ALL H3 questions go.

The I5 to V8 swap is not a direct bolt in, more to it that you might think. You would be much further ahead if you do the work to the I5 than sell it for an H3 Alpha.

Either way, welcome and good luck.

 

low compression could be bad valve seats on the head.

 

That was my hope. But a wet compression test (few ounces of oil in the cylinder) temporarily seals the rings. So on the second test it went from 35 to 200. If it was the valve seats it would not change compression with such a test. So, bad rings.

 

it does sound like your wet test does confirm stuck damaged rings

 

If you can wrench and do the work yourself, have access to cheap salvage parts locally and as you said, not in a hurry, go 6.0 (same work as a 5.3 and can be found cheaply), expect 5K
If it will be done outside, 10-15K is a good ball park assuming you got cheap parts first, otherwise 15-20 with all new parts (except engine)

 

keep in mind also the wiring and tuning involved. if you dont do it yourself then hope the person that does do the work is reliable as they will be the only ones that know what was done which might bite you in the *** later down the road

 

Based on comments I've pretty much decided to keep it stock and just rebuild it. I ran a scope down the bad cylinder this morning, and Its pretty bad. Major scoring. Can these sleeved cylinders be bored? I so, by how much?

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A vote for simple rebuild....

 

That is now the plan. I bore scoped the cylinder. The wall doesn't look to bad but will need 1 over for sure. Won't know until I tear it down and have the shop mic it. The problem was the piston. Broke at the edge, about 1/2 long, at the ring lip. Poor design? Saw a video of this same break happening when a turbo was installed. Not the case here.

Anyone know if they make an off the shelf set of forged Pistons for the things? May as well upgrade...