Compression Test Questions for Pre-Purchase
 

Hello everyone, so one of my good friends is selling their 2006 Rx-8 mostly stock. Has cold air intake, and hollowed catalytic converter . She has had it for a while and we actually drove across the country (usa) in it. Her dad spent around $6,000 doing a rebuild on it around 25,000 miles ago. so I told them I was interested in buying it. They are willing to sell it to me for $3,500. I took it to our Mazda dealer to have a compression test ran on it and they totally screwed me over I think. Apparently they didn't have the service tool so they did it the same way I could have done myself. Then they told me rotor #1 tested at 85 psi and rotor #2 at 90 psi....

Don't I need a PSI reading for each rotor face? so 6 readings in total?
Lets just say the it tested at 85 85 85 psi and 90 90 90 psi how much life could I expect from the Engine if well maintained?
https://cimg1.ibsrv.net/gimg/www.rx8...1a0b04af43.jpg

If they charged you to test the compression, and then admitted they tested the compression and didn't have the proper tools to do so, then they charged you for a service they did not perform. It might sound like a pain in the ass, but go back to them and tell them they need to redo it with the appropriate tool. If they refuse, just tell Mazda North America (corporate) that the dealer charged you for a service they did not perform correctly because they did not use the tool designed to be used for the service and you want the service redone correctly with the correct tools.

There should be 3 numbers per rotor so this "test" seems suspect. Also, no way to know if its an apex seal problem simply from a compression test. There could be other reasons why the compression is low. 100 PSI is recommended spec but it could be other factors like carbon buildup thats causing these numbers. Either way, I wouldn't trust this report since they obviously didn't use a rotary compression tester nor did they correctly test the engine with a regular compression tester.

I had a dealer do exactly this, and after they showed me the resultsa d a friendly chat , the service manager agreed it was not a service they could charge money for.

85 and 90 could be good, could be bad, depends on what rpm those readings are from. So yeah get a proper test and your money back.