Compression test

[gmcman]

With the Voy getting up there in mileage, 287K, I want to do a lot of preventive maintenance in the next few months and freshen things up.

One area is to replace all the lash adjusters but don't want to do this if the motor shows signs of being on it's last leg.

This is my 2nd compression test, last one was roughly 100K miles ago...need to double check that.

Results were a little better than I thought, they were very close to the last test. Number 4 worried me at first, didn't want to go past 160 psi. I checked the tester and was able to turn it about another 3/4 turn so after that it hit 180 right away and settled at 190.

All cylinders hit about 100 psi on the first compression, then about 180, then finally resting where they were...about 4 compressions each.

This was a dry test, #4&5 were just slightly low, but still very good for the mileage. I was pressed for time, I want to speculate if I was able clean all the anti-seize from the threads, get a good tight seal, and crank it over about 8 times or more the results would be more even...but overall they are respectable.

 

[Sparky]

Looks good to me. Just under 10% difference between highest and lowest.

 

[Mooseman]

Manual says "normal" should be 215psi but I think that's an average at average wear. 4 out of 6 hit almost 210 with the other 2 at about 190 is pretty good with that mileage. Mine with 120k km was in the 240's.

I don't think it's worth it to replace the valve lifters or lash adjusters. If it was well maintained with regular oil changes, they shouldn't give you any problems. And if one does, deal with it then.

Another thing to check is actual oil pressure (not from the fake dash gauge). All I could find in GM-SI was that it should be 12psi at 1200rpm.

 

[gmcman]

Thanks for the tips.

I guess the reason I'm looking to change the lash adjusters is that slight tick near the top of the motor. Hard to pinpoint it but I'm leaning on the lash adjusters

The 215 psi...was that on a cold or hot engine? My test was done on a cold motor, I agree the results are pretty good based on mileage....the engine runs fine.

 

[Mooseman]

The 215 psi...was that on a cold or hot engine? My test was done on a cold motor, I agree the results are pretty good based on mileage....the engine runs fine.

It doesn't say. I would assume cold since the plugs are supposed to be removed on a cold engine.