dubrado

iTrader: (20)

going to do a compression check this weekend...and was wondering what the psi for the cylinders should be for a stock 01 5.3L

thanks!

mudz5.3

I say atleast 160-175 psi. How many miles?

dubrado

iTrader: (20)

last owner said 14k

mudz5.3

eh, its a little on the low side to me but still manageable. Psi numbers on beamers are over 200 normally, lower mileage though.

one03sierra

iTrader: (1)

i think they are suppose to be near 125 to 140 psi. you will need to be worried more about them being less than 10% difference between cylinders.

dubrado

iTrader: (20)

ya, i looked at some of the ls1 guys and they're numbers are higher, closer to 200 psi, I did some reading up and they said to just make sure the numbers are consistent and that the max variation between cylinders is no more than 30%

now I just need to cross my fingers and hope compression #'s are ok and pray that this motor doesn't have piston slap from hell

one03sierra

iTrader: (1)

yes the ls1's will yield bigger numbers than our 5.3's will. 10% is a little low,i try to keep it at less than 20% varience.

bigguy75inches

around 130 ish is normal.. the factory service manual even has a formula for those cylinders that might be slightly normal.. i think take like your highest compression cylinder, lets say 130psi. then figure out like 20% of the highest. that number is 26. the lowest cylinder compression level should not be lower than 26psi than the highest. if so.. its considered ubnormal and should be fixed. if forget the EXACT percentage. but i know its close to 20% i think. if someone really needs this info.. i will try to dig up my manuals. and find it.

bigguy75inches

opps, i totaly skipped your post 02 denali. what you said. lol