Bad compression test blah!!!!!!!

[blackrosenova40]

Well I did a compression test and here are the results as follows....

1. 100
2. 87
3. 85
4. 90

After that I was a lil peed off, but I did a wet test on # 3 and it bumped up to 125.

On a further note my camshaft timing is exactly 10 degrees advanced, how much would that affect my compression results?

 

[flashburn02]

With compression all over the place like that, you are probably looking at a new head gasket. Do you have coolant in your oil? Check the dipstick.

 

[blackrosenova40]

Nope, I installed a new head gasket about 30,000 miles ago with arp head studs. There is no coolant in the oil at all.

 

[Cs4g63]

It is most likely going to be your piston rings that are bad. The fact that you did a wet test on #3 and it went up 40 shows that your rings arent sealing enough on their own anymore.

 

[blackrosenova40]

I have a question then. Since my compression readings are so low, would that cause my car to pull low vacuum or not, because I am reading 19 inches at idle.

Also if my rings were that bad wouldnt I be blowing smoke?

 

[Splitpi]

I think cylinder 3 definitally has bad rings. 131 psi is the minimum for a 90 4g63.

Someone else chime in, but if your cam is off by 10 degrees, you may have jumped 1 tooth.

 

[blackrosenova40]

From what I can tell it looks like its actually off by three teeth. But what I do know for sure is the cams are 10 degrees advanced.

Anybody know if this would lower my compression test readings?

 

[blackrosenova40]

When a belt jumps timing, do the cams usually advance or does the cranks usually advance?

 

[flashburn02]

When a belt jumps timing, do the cams usually advance or does the cranks usually advance?

It doesn't matter which advances because its a closed system after they jump. There is no way of telling if only one cam advanced because the belt rides evenly over both cams. So after your belt slips and regains grip, the entire system is affected.

 

[Splitpi]

Your compression test is suspect to failure because your timing is off due to the jumped cams. they may be staying open and causing the low compression. Reset the timing of the cams/crank/oil pump/balance shafts and then retry.

Also if you did jump a bit, you "may" and I stress the may have, chipped the valves.