Last Saturday I was finally able to get my Rx7 to start up and go for a cruise. Even after sitting for a couple of months it still doesn't smoke after 227,000 miles. It ran pretty nice, but I'm still wondering why the compression is low. A while back I was told that the car had several oil leaks including the oil pan (gasket), OMP gaskets, and oil filter adapter stand base too. I plan on fixing all these leaks, but I wonder if they might be causing the compression to be low (oil pressure never reads above 70 and drops when the car is at stops). Anyways if those repairs don't help then I guess I will decarbonize the engine. Another strange thing is that with all those oil leaks the car doesn't really lose that much oil.

 

70 pounds of oil pressure seems pretty good to me...especially at 227,000 miles. And it's normal for it to drop some at idle. Is that how you're judging that it has low compression? Or did you do it the right way and take a compression test?

Rich

 

my oil pressure guage always changes according to my rpms. driving its like 60 psi and drops at idle.

 

The oil leaks themselves will not cause low compression, they just indicate that the engine is old and its not sealing off things as well as it should. Your oil pressure sounds normal to me.

Low compression is caused by lack of a seal on the rotor. The rotor seals by dragging around small "soft" parts that conform to the housing as the rotor spins around, like apex seals as an example. Oil is injected into the carb so that these seals get lubricated so they seal better and last longer. So make sure the OMP is doing its job, if its not up to snuff this will cause you problems. Given that you have 227K on it, I'm not surprised you have leaks or low compression. Its really a matter of whether you can tolerate the way it performs. It may run for a lot longer just with lower compression == less power.