Low Comp Numbers

[WongWay]

I took my 90 Talon to a friends shop to check out a bad vibration, I was pretty sure it was a BS issue. Well it turns out the oil BS was 6 teeth out of time. In the process we learn that the lower timing cover was tore up and started eating into the Tbelt. Needless to say we replaced all the timing components, while he was at it I asked him to do a compression test.

The comp number came out really low 1/100 2/85 3/65 4/100. When he told me this my first question was about his process. He did a cold motor test, he says all plugs where out and it was done at WOT. My plan is to redo the test on a hot motor. My question is I don't seem to have any other issues that point to bad rings or HG. No smoke, and the oil/coolant is clean.

Redo comp and do a leakdown test next??

 

[Sp1kE]

bingo

 

[JamesH]

The car would run like complete crap when you start getting that low. I would redo the test. How does it run now with the new BS and timing belt?

 

[Anubis_4_99]

The car would run like complete crap when you start getting that low. I would redo the test. How does it run now with the new BS and timing belt?

Not necessarily, i've had cars that had 60PSI in two cylinders that ran like a top. Don't generalize unless you have facts to back it up.

 

[JamesH]

I have a 1.8T Jetta sitting in my bay right now with 10in of vacuum and 65 and 70 psi on the center cylinders. Car runs like complete crap because there isn't enough compression to even burn the fuel in the cylinder. When I can get it running it runs like crap with a miss at idle and under load won't fire at all.

I don't need facts. It's basic knowledge. A car with half it's needed compression will run like junk. Perhaps your idea of "running like a top" is slightly distorted because it will not.