Compression test results what do you think?

[ERIC87442]

So i have an 87 olds 442 vin9 307 with 48k miles i did a compression test today, heres my results what do you think?
cyl 1 135psi
cyl 3 135psi
cyl 5 130psi
cyl 7 105psi

cyl 2 115psi
cyl 4 85psi
cyl 6 125psi
cyl 8 110psi

 

[Doober]

Passenger side is a little low... driver's side looks ok. Were you thinking of a rebuild?

 

[SafariWagon]

Probably runs but ,looks like a rebuild is in your future. # 4 and #7 would bother me. I am running about 185 pounds on a fresh rebuild. Thicker head gaskets are in my future. I have too much. About 170 Pounds max for premium gas and iron heads.

 

[ERIC87442]

well im getting alot of blow-by thinkin of pullin the heads and cleanin the heads and doing the headgaskets while im at it, i think its got a bad headgasket, the guy i bought it from was a gm mechanic for 37 years and said he use to work on these everyday and he would put his money on it having a bad headgasket due to the fact that they were known for blowing head gaskets

 

[Doober]

Cheapest route for now I think would be head gaskets and lap the valves. Plus you'll be able to see if the low pressure pistons have any different coloring that could be a sign as well.

Also, I'm pretty sure these engines are still 8.5:1, so pressure won't be as high to start with.

 

[bjohn07]

So i have an 87 olds 442 vin9 307 with 48k miles i did a compression test today, heres my results what do you think?
cyl 1 135psi
cyl 3 135psi
cyl 5 130psi
cyl 7 105psi

cyl 2 115psi
cyl 4 85psi
cyl 6 125psi
cyl 8 110psi

did u take the compression test after the motor got up to operating temp? wet or dry test?

 

[Doober]

Forgot to ask that... but even cold it should still have halfway decent compression.

 

[ERIC87442]

it was cold, all i did was disable the ignition and cranked it over

 

[bjohn07]

Forgot to ask that... but even cold it should still have halfway decent compression.

yeah it should, mine had 150 on all 8 cold and dry test. but some engines with some miles might need to be warmed. i would get it to operating temp. shut it down them disable ur ignition to check it again. then after that test. dump a couple squirts of motor oil in each cylinder before u hook up the compression guage to it. let us know how much if any the numbers come up.

 

[Doober]

Yeah, the rings/pistons heat up and expand, helps seal a little better.