Rebuilt motor or replace the rings/pistons

[hunter01]

My chilton says for a 91 Z motor the compression ratio is 9.3:1.
It also says " A cylinders compression pressure is usually acceptable if it is not less than 80% of the highest reading. For example, if the highest reading is 150 psi, the lowest should be no lower than 120 psi. No cylinder should be less than 100 psi."

[vtmecheng]

Make sure you disconnect the ignition coil from the distributor to keep the engine from firing up. It will fire up with one cylinder disconnected so watch out.

[Mango™]

The truck only smokes when I punch the gas or hold it down. Somebody was saying it is the rings, he said if it smokes on start up it is the valve seals, any suggestions? I am thinking of buying an rebuild long block

[vtmecheng]

That is correct, if it is the valve seals you will see a nice blue smoke cloud at start up. If it smokes with the hammer down I would lean toward the rings but a compression test will tell you a lot.

[Mikado14]

Compression test, Compression test, Compression test, Compression test, Compression test.

Please do this first. What you have stated about the rings and valve seals is correct generally. There was a recall on 5.3L from '01 that had bad valve seals and it would puff blue smoke when the throttle was tromped. Compression test was good. GM replaced the valve seals under warranty and it is now fine.

[Mango™]

Well I skipped the test and went on an luck,
I changed the plugs, wires, egr valve, air filter, pvc valve, oil and filter and put in an $10.00 bottle of injector cleaner and IT PASSED, whoo hoo.

[BlazerLT]

Amazing what maintanence will do eh?

[dmbrisket 51]

Originally Posted by BlazerLT

Amazing what maintanence will do eh?

mango, pvc is that plastic stuff our sewage pipe is made out of, you changed the pcv valve...i hope (sorry grew up with construction work, and i realized you just hit keys backasswords)but on a serious note, next oil change, use high mileage moter oil, synthetic or patrolium its up to you, but remember to totaly drain the moter if your switchen, also the rad cap and fuel filter should prolly get a changen too

[Mango™]

lol PVC, I will do that on the next oil change.
Thanks all