Compression Question
 

Hi...

Will the following compression numbers (done with wide open throttle while cranking the engine) cause an engine not to start?

1) cylinder #1 has 100psi of compression
2) cylinder #2 has 100psi of compression
3) cylinder #3 has 130psi of compression
4) cylinder #4 has 80psi of compression

It's from a D15B7 engine. Thanks.

i would say from those numbers that motor is cooked.usually should be from 180-220

That I think is too high for a D series engine.

matter is pretty much toast.

If its your motor.. do a leak down test to see what's the cause

Wow....Not good resuts at all.

did you have the gauge screwed in tightly??? if so, that engine is toasted. lowest I'd expect to see would be like a 150ish.

Thanks for all your reply. So, would you agree that even if everything else works properly (e.g. dizzy, spark plugs etc), the engine still shouldn't start?

no it won't start with that compression, but it should TRY to fire. as in you should get the typical cough cough cough of combustion. like when a lawnmower doesn't start on the first try lol

You've been trying to start a dead engine for 2 months, with no luck. There's no oil left on the cylinder walls for the rings to seal to. Try a wet test: Add 3 or 4 drops of oil into each combustion chamber before you test. Compression will go up. If not, get a leakdown test to see where you're losing compression.

I added a few drops of oil in each combustion chamber and here are the compression test results:

1) cylinder #1 has 150psi of compression
2) cylinder #2 has 150psi of compression
3) cylinder #3 has 140psi of compression
4) cylinder #4 has 130psi of compression

So it seems that the compression looks ok? However, the engine will still not start. Can any one please help? FYI, I'm getting strong sparks from each of the 4 spark plugs (sparks jumped a 1/2" gap), and I'm getting fuel in the combustion chamber. The engine did try to cough for 1 to 2 seconds after I've dried up the spark plugs - they were covered with fuel. After the 1 to 2 seconds coughing, the engine won't even cough - just crank, crank, crank. I've tested the ECU, main relay, fuel pump and they are all working properly. The battery is fully charged.

Fuel seems like its your problem, check your FPR. If the fuel pressure is fine then you may want to think about piston rings.

Rings are shot, might as well replace the motor, time for an upgrade????

"fuel is getting to the combustion chamber"

good call there buddy:thumbup:


i would replace the motor. What is it? a b7? those things are a dime a dozen