droptop94

I have an 85 Mazda RX7.
Came out one day and it would not start.
So I made sure it was getting fuel.
Then made sure I had good spark to all the plugs.
So decided to do a compression test. On the 2 spark plugs closes to the radiator I have 60psi but on the back 2 closes to the fire wall there is 0 compression.
I have worked on lots of cars but never a rotary motor, but seems to me there should be the same compression at all spark plug holes.
Any help or advice would be appreciated.
Thanks.

drftk1d

You can try pouring a bit of marvel mystery oil or auto tranny fluid into the spark plug hole that's giving you no compression and try to turn it by hand before cranking it.

even though the rear rotor generally has lower compression than the front (for whatever reason), those numbers are really low. You might be looking at a rebuild. Healthy motors are normally around 100-90 psi, and a little lower for older engines

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RX-7 TII

SMOKINROTORS

from the factory 95% of 12a's and 13b's which are found in all models including the 3rd gen and rx8 should have 3 even bounces of 80 to 85psi on a normal comp tester with the shrader valve out and your gogo pedal to the floor. with the exception of the 88gtu that i know of came from the fac with 95psi on all 6 seals