compression results

[shortyskater]

Just did a compression test and these are my results. 1-4: 159, 152, 149, 160. How does that look? Should I worry about #2 and 3 cylinders? Also I seem to be loosing oil. Not sure if I'm burning it or not since its cold out. There was no oil on the plugs when I pulled them. Any ideas?

 

[fastasseclips95]

How much oil are you losing? I assume you have checked for leaks and have nothing on the ground where you usually park the car?

 

[92AWDHX40]

Those arent bad, is this car new to you.

 

[Kastigir]

Only 11 psi difference across cylinders is fine. Couple of questions though, was this a warm or cold test? Wet or dry? How many cranks before taking the reading? For a 1g, and someone can correct me if I'm wrong, but those numbers seem a little low for a warm, wet, 7 crank test, reading.

 

[MichaelSuch]

They are a tad low to me but nothing bad... Is you're coolant changing to a brownish color? It may be possible that your headgasket is bad and that's why your losing oil (mixing with the coolant) and low compression in those 2 cylinders.

My service manual for a '92 says that the standard value for a turbo engine is 164 psi, minimum is 121 psi. The max pressure difference between each cylinder is 14 psi.

How many miles are on the motor? Has it ever over heated?

 

[shortyskater]

The test was hot and I poured a cap of oil down cylinder 3 and the results went up. There's 114xxx on the motor with a rebuilt head like 2000 miles ago. I purchased the car a month ago and the guy rebuilt the head due to the timing belt snapping and bending some valves. I don't think it's the head gasket since the oils not milky and the coolants not brownish. There's no oil spots under my car so I'm stumped. After checking the level and seeing it was full 1500 miles ago, the other day I had to add about 2 quarts. Any ideas. Sorry for such a long post.

 

[shortyskater]

Oh and it's never overheated. This is my first turbo car but not first dam.

 

[alansupra94]

It is possible that your piston ring in #3 is getting worn out though your numbers do not seem that bad.

 

[nate379]

Good rule of thumb is your lowest cylinder should be within 10% of your highest.

 

[talonDSMerr]

Pouring a cap of oil into the cylinder will raise the compression regardless of a bad ring or not, it won't really tell you anything. The best thing to do to check is to use a leak down tester with compressed air in the cylinders. Then you can find out where you might be leaking pressure to.

 

[shortyskater]

Ya I was planning on calling some shops around to get a leak down test done since I don't have the tool. Other wise I shouldn't really worry about anything? I'm going to be changing the tubro out from stock to a Evo3 16g and putting a front mount on. I guess the last place to really look is the tubo to see if maybe its leaking around that since theres no visible evidence of it leaking else where. I guess I'll keep an eye on the level more often and just check some other things. Thanks for everyones imput. Greatly appreciated.

 

[toofast82]

Those numbers arent bad for 114k. On my 90gst, years back. i did a compression test and every cylinder was 145 and it cracked a piston a week later.
Its a 1g, its got to be leaking something

 

[DSM_ThuNDeR]

FIRST, start out by looking at the o-rings on the valve cover gasket- inspect if there is oil around the walls where the spark plug's go. First things are first, then jump into internal engine conclusions.

 

[91tizzy]

those are actually really good numbers....cant understand why some of our fellow first gen owners are not actually sayin how good they are.....not perfect brand new motor good but definately good for a stock bottm end with a little mileage on her....the rings are probably fine in number three....when you poured the cap full of oil in there all that it did was raise your compression by taking up volumetric space in the combustion chamber....none of that oil actually made it to the rings due to our low compression piston dish design. My numbers are about 150,150,145,139....never get a peep out of her and she runs like a top. My buddys are about 140 all the way across and he is runnin really freakin stout on his stock 160,000 mile shortblock and valve components. I wont worry about a rebuild till I here a noise or she drops compression much lower than 130.....btw guys the comp numbers dont have to be 165 straight across the board to have a healthy motor by any means....real world experience proves that....that and with all the guys on here makin such power on relatively stock high mileage motors AND trannies (in automatic situations )

end rant

OP keep oil in her....do a leakdown for piece of mind....do your power mods with the supporting mods a step at a time and she will take good care of you


haha talon dsmer got to it before i realized it about the cap full of oil....good information to spread

 

[anteversion]

those are actually really good numbers....cant understand why some of our fellow first gen owners are not actually sayin how good they are.....not perfect brand new motor good but definately good for a stock bottm end with a little mileage on her....the rings are probably fine in number three....when you poured the cap full of oil in there all that it did was raise your compression by taking up volumetric space in the combustion chamber....none of that oil actually made it to the rings due to our low compression piston dish design. My numbers are about 150,150,145,139....never get a peep out of her and she runs like a top. My buddys are about 140 all the way across and he is runnin really freakin stout on his stock 160,000 mile shortblock and valve components. I wont worry about a rebuild till I here a noise or she drops compression much lower than 130.....btw guys the comp numbers dont have to be 165 straight across the board to have a healthy motor by any means....real world experience proves that....that and with all the guys on here makin such power on relatively stock high mileage motors AND trannies (in automatic situations )

end rant

OP keep oil in her....do a leakdown for piece of mind....do your power mods with the supporting mods a step at a time and she will take good care of you

+1 for sure
Thats the better answer that you could have for this question!

 

[shortyskater]

Thanks a lot. I feel better now.