This weekend I am doing a compression test on an FC that I may purchase. The car was in storeage. The motor has not run in a couple of years, but has been 'regularly' turned over, whatever that means. I heard the motor crank, so I know it is not locked up.

http://www.rotaryresurrection.com/ro...lder/comp.html

Is there anything special or extra that I should add to the proceedure to assure that the results are accurate for this stored engine?

Thanks

Jack

 

just make sure compression is over or at 95psi. no blow seals, your golden.

Zak

 

your gonna wanna drive it and see it run...cause even if you have compression...you have have a bad oil or coolant seal...compression isnt everything...

 

Warm the engine up before you do the compression test. A cold motor wont achieve as high of compression #s.

Curious, whyd you hear it crank but not run? Or am I just assuming that you didnt hear it run?

 

just to clarify when i said " just make sure compression is over or at 95psi. no blown seals, your golden."...

i was refering to him saying anything special or extra, i assumed he would test drive, and check other areas as well, i was just pretaining (sp) my statement to his statement, if you can follow what im trying to say.

but yes, i agree he should also check coolant, and all the extra goodies.

Zak

 

I'm sorry, I didn't explain the situation as well as I could have. The car will crank, the car will not start, so I cannot warm it up first. Of course, it ran before storage, they all do, right?

It would be a project or a partout. Since I cannot warm it up and drive it, I thought there might be something I could do like squirt a little oil in the plug holes or something to help get a good idea of the condition of the apex seals. I also don't want to do something that might make the compression test out higher than it really is.

Suggestions?

Thanks

 

when it cranks cold, if you see white smoke, then you need to run one more test, the coolant bubble test. My .02, if it isnt alredy covered in the rotary res page

 

My old motor was toast (not 1 apex seal left in the rear rotor), it would still start and idle @ 1700rpm if you pull started it. Ran pretty rough and back fired lots, but you could drive it around on just the front rotor if you really wanted to.

 

i think your not gonna find alot of fcs at 95psi many of them can have less and not give you a problem,my convetible is at 80psi at both rotors and it runns perfect,it turns on at the fist crank
i would say anything over 85 and over psi is a good buy.

 

https://www.rx7club.com/showpost.php?p=5358610&postcount=125

Cold comp. test reads higher according to RotaryResurrection. Warm test gives a more "true" compression reading.

 

to add if you look in a mazda shop manual it states that compresion should be at 85 psi

 

no that is the lowest tolerable compression numbers.

 

anything under 85 its about time to start looking for a rebuild, a very well mainted fc that wasnt abused (i dont mean it was never driven i mean ABUSED) should be in the 100-95 range.