Compression test HELP!
never used a comp tester before!
I rented one from autozone...it came with a little screw in thingie..I screwied it into the spark plug hole..then screwed the hose into the end of that...then popped the other end of the hose into the gauge. When I turn the engine over with someone watching the gauge..the needle doesnt move at ALL. I have the throttle wide open too so itll suck in air, and the fuel is off..and the plug wires are off... |
Did you follow the instructions that came with the gauge?
Some gauges have a small valve that needs to be opened. In order to get a proper reading on a rotary you need to use the leading spark plug hole and remove the Schrader valve from the gauge (or hold the pressure relief open). |
Tried with pressure release open.
There are no instructions with an Auto Zone rental gauge lol...and that valve is integrated into the hose itself...couldnt remove it. |
Maybe the tester is broken?
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That was my conclusion.
Even a totally fucked up engine with no apex seals what-soever and a housing scarred to hell and back..the rotor should be moving enough air to make the needle jump to at least 10psi |
I did a compression test today. I got 120 in the front rotor and 90 in the back rotor. I heard they can be different, but 30 psi difference seems like a lot to me. What should I do next?
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How did you do the test? If you just used a conventional tester and let the pressure build to a single results, that doesn't provide the information you need to evaluate the health of your engine. A proper compression test needs to provide the readings for each face of each rotor and the engine cranking speed at the time of the test. This requires a special compression tester.
However, there are procedures for doing a simple ghetto test with a conventional tester, so do a search for the instructions. The specification for an S5 is a minimum of 85 psi@250 rpm and a minimum difference between rotor faces of 21 psi@250 rpm. To answer your question, if after you do a proper test the results are close to the above spec, the engine starts and run OK, just continue to drive the car. Edit: Here are instructions on doing a simple compression test http://www.aaroncake.net/rx-7/blown.htm |
Good info
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