What does a compression test do???
 

I'd like to know what a compression test does. shows you the life on the motor, the condition its in, or how much time untill a rebuild? these are all things that I've herd about the results of a compression test. any help would be appreciated thanks. And what would be somethings to look for when buying an fd with 45km miles on it and will be my dd but isnt daily driven currently?

Look here: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/faq-3rd-gen-other-useful-links-68640/

Quick ... someone lock this thread before anyone can FLAME this poor noob

:dienewbie

uhh... it tests the compression of the engine? :uhh:'

A compression test, in this case, tells you how well the apex seals are sealing against the rotor housing. Apex seals are the equivalent of piston rings where both of these are vital to your engine's life. Very low compression numbers mean that the engine being tested is not very good. Look over the link MrNizzles gave you and you'll find very good information. Theres also a search feature located towards the top right hand corner of the forum. Use that before posting a question. Odds are your question has been answered a few times. Good luck.

Compression and no major coolant and oil leaks? For a daily driver I would replace all the factory coolant hoses and clamps, replace the Fuel Pulsation Dampner, and buy another quality DD:)

And another one gone, and another one gone,
Another one bites the dust!

[/Queen]

Nothing more than a health indicator. Can't tell you how long it will last just if it's wearing evenly and in good health. Low number typically indicate worn out but could indicate hasn't been run lately. Higher numbers lean towards a life ahead but certianly don't tell you if it will die tomorrow.