Originally Posted by Oddjob

Couple thoughts:

If the car was running fine, then shut off and would not start - that is most likely not a compression problem, unless the t-belt failed and it bent valves. If it was over rev'd to 10k on a missed shift, it might also have had some valve contact.

I have done the WOT testing with the car running on 2 cylinders. And I have burned an exhaust valve on track and ran a couple laps trying to figure out what was causing the drop in power. It would still pull 120mph down the straight w/ zero compression on #4.

I was also in the passenger seat of a 89T that broke a #1 rod on track, and blew the engine apart. It also had burned a #4 exhaust valve during the incident. The driver/owner had to turn the motor off with the key, because it was still running.


I would recommend checking all the common fuel and ignition failure points (DME relay, ign coil, cap and rotor, spd ref sensors, fuel pump, etc) before pulling the head.

Originally Posted by Van

Remember, there are two TDCs... one on the power stroke (at combustion) and one after the exhaust stroke. For this second one, the intake valve will be partially open (remember, the intake opens a little before TDC to maximize the air flowing into the cylinder).

I think it's much more likely that you just have a blown head gasket.

Originally Posted by Oddjob

When you crank it over - is it firing at all? Any popping or smoking? Or just cranking?

Originally Posted by Chris White

It could be burnt valves – typically that would had a ‘chuffing’ sound at cranking since the area of the valve that is missing is fairly small you can hear the air escaping past it as you crank the engine.

Hearing the air in the intake during a leak down test would not be typical of a burnt valve – It’s the exhaust valves that get burnt.

I would also expect an engine with the compression numbers you listed to still start and run – maybe not very smooth but it should run and idle.

Sounds like you have something else going on….

Originally Posted by Tedro951

Van clarified the reason I asked about TDC in each cyl. For a leak down check, think 8 TDC's....only 4 will work for the test.

Manny, this is where I was heading. Low compression in a few cyls wont stop an engine.

Originally Posted by Van

Also remember that you'll get a little leak-down past the rings, which will go into the crankcase, which will go to the AOS, which will go to the breather/PCV, which vents into the intake (j-boot) for emissions... This will cause air to be in the intake, although it's not getting their via an intake valve.

Originally Posted by carlege

What was compression before the problem?

Originally Posted by lart951

Sold my head to minho for $ 200.00 shipped I bet you can't beat that.

Originally Posted by Jeff N.

Yes. The spark timing is all off. This doesn't explain your compression issues.