I have a 12A Mazda reman motor with about 20k miles in an IT7 racecar.

Last season, the motor ran great, no issues.

First practice day this season, the motor was running fine, but alot of oil was leaking past the rear main seal. Oil was getting out around the inspection covers, and after each run, the car would make a nice puddle under the car. Over three 20 minute sessions, it lost about 1/2 quart.

Also, toward the end of the test and tune day, the motor sounded kind of flat in the lower rpm's ~4-5k rpm.

Is there an internal failure mode for the engine that will pressurize the oil system and push oil out the rear main? Maybe a broken side seal?

I need to do a compression test, and then pull the motor, but I was just wondering if this is a common sign of an engine problem. I'm hoping that it's a problem of venting the crankcase, but I haven't made any changes since last year.

Thanks,
Neil

 

If the engine isn't burning oil, the side seals and oil control rings should be good. Pull the tranny and flywheel and replace the rear main seal. The oil control ring seals the front side of the rear iron, the rear main seals the rear, with the oil galleys in between.

If the motor sat between seasons, the flatness may indicate some internal carb cleaning is needed.