The Stovebolt Site Forums The Shop Area Engine Shop This is a new one on me.

I did a compression test on the 216 in my 52. I had low readings on the dry test. On the wet test the readings were even lower. Yes the procedure was the same on both tests, to include the amount of oil I squirted in, the same number of cranks, evrything. Cylinders 1 and 6 had the highest readings, 90-95 wet, possible warped head?? But, no contamination of anti freez or oil.

I think it may be time for a different engine.

Was the engine cranking at the same speed?just a thought...Tom

Yes, three surges each time. This is a 6V system.

Sounds like your compression guage is getting some oil in it making the readings inaccurate,
Scott

Thanks Scott,

That makes sense and I will do another test. I did use more oil than I usually do, just to make sure to rings were sealed.

Mike

I agree with the gauge being the trouble. There is a check valve somewhere in the gauge, usually at the cylinder end of the hose or fitting- depending on what kind of gauge you have. If the check valve is sticking, you will have low compression readings. Your pressures are pretty low for a wet check.

Have you used that compression gauge on other engines, and found better/higher pressures? If not, the check valve in your gauge may have been replaced with a tire valve, which will/may cause lower compression readings because tire valves have stiffer springs. A stiff spring means delayed opening under pressure and early closing as the pressure nears the peak- result- a lower pressure reading. Most compression gauges have very weak check valve springs.

Harvester

Harvester;

I have used it and had higher numbers.I bought this new and have only used a few times. I will lookit over and do the test again this weekend.

Thanks,

Mike

OK; I borrowed another gauge and tried again. This time no pressure in any cylinder. All the plugs were out. It would show compression but leak down immediately. I am going to try a running compression test tomorrow.

This engine will still run, no fluid contamination, no leaks, no blow by, no smoke.

Lets see you have no compression and the engine runs. Call GM R&D you have a new type of engine.
Just kidding, I think you have another bad gauge.

The Shrader valve on the tester is stuck. Time for another one,
Scott

How is the engine running? Why are you testing?

I've never run the motor when cheching comp,I knew a guy that did it all the time,his comp gadges only lasted about 2 months.He said that that's how they are supposed to work!I'd go for the schrader valve,I've had em go bad for me.Got spare's from the snap on truck,not to expensive either.Tom