I have a question. I’m looking to buy a 2009 rx8r3. The guy seems to know how to maintain the car. He says the body has 111k but has a new(ish) engine with 40k on it. Everything seems to be normal but when we talked about compression test all he said was 1 face on rear had a compression of 89 and that was the lowest number in the whole engine. Is that normal? And why did he not tell me all 6 numbers? Is it typical to only remember the lowest number? Also, should I be concerned about anything else? (Parts with original 111k miles going bad?) Or should I be concerned about the engine that’s in it now?

 

No, a proper rotary compression test will yield at least 7 numbers, usually 8.
You should get 3 pressures for each rotor and 1 or 2 RPM numbers.

It sounds to me like he/they used a piston engine compression tester with the check valve removed.

If you like the car, offer to pay for a proper compression test at a Mazda dealer. If he agrees, meet him there or take it yourself and get the results directly from the service adviser.

 

Alright I appreciate it, do you know how much they cost?

 

Book rate should be 1 - 2 hour of labor. I don't know the shop labor costs in your area so I can't say for sure the exact price. You can call a dealer service department and ask them.

 

I've been quoted $75-200 USD for a compression test in the past. In my experience it depends on the dealer/area.

 

$75 is probably from a rotary shop. $200 sounds like a Mazda dealer.

Even with the poor man's compression test, 89 psi is low, that's especially considering the S2's stronger starter.