Weird compression test results
 

About 3 years ago .. i did a compression test on my motor with a piston tester following all the guides from rotary resurrection and banzai ect.

My compression numbers were bouncing at 65psi..

I then got a mazda compression test done and they were 7.8-8.0

so thats was good..

fast forward to now .. i just did the compression test again with a brand new piston tester and got the same pulses at 65psi.

am i missing something here ?

i though the pulses were to be at 100psi.

Id like to get it done at another rotary test done for piece of mind but shop that did my last one is no longer around..

ive been through over 15pages of search results on compression testing and am still lost on this.

so what was the senario you did the comp test under? was the engine cold or hot? did you expect the current PSI to increase or something? with a piston tester just look for 3 even bounces thats honestly all its good for. if you want to reinstall the one way check and check MAX psi after you have verfied even pulses thats where you may get your 100psi with a piston comp tester. other wise a true rotary comp tester is the only true way, either the mazda original or a 3rd company equivalent you can buy.

BUT back to your 60 psi. if its even the car starts hot and you arent having issues dont worry. although the type of comp tester you use may give greater or less PSI bounces pending things likelength of hose it has servicability/leaks and the flex of said rubber on the comp tester.

so take your pick but you have stated it was 65 before and 65 now so whats the deal?

z

Without a real rotary compression tester, all you'll really know is good or bad. Sounds like you're looking for exact readings......

its more that im worried as to why i cannot duplicate the compression tests that others have done . i put the shrader valve back in and got 70 psi. but then the bounces were only 35psi.

engine was at operating temperatures and the pedal was to the floor . the faces were all even .

I guess im just getting a little worried since the car has 5 years on the motor and 20k/3 years of the miles have been single turbo..

and your point is..... look not being a dick but if your not having issues not a problem period.

BUT if you want to find out get a REAL rotary comp tester or take it to someone that has one. or you will never get "what everyone else is getting".

z

a compression gauge should see 3 even bounces somewhere above 95psi

banzai's directions are simple. if you followed them, and seen 3 even bounces at 65 then your motor is just worn. it would be wise at this juncture to rebuild your motor instead of waiting for it to blow, and spending hundreds more on housings/rotors.. turbo and whatever else may be damaged from apex seal failure or overheating.

did you remove BOTH trailing and leading plugs or just 1? and was the engine warm. if a rotary mechanic did a compression test and said your engine is good then take his word for it.