If the car's compression is 100 in the front and 80 in the back is it time for a rebuild?

 

Yea it is getting time for a rebuild, It should start (Maybe Hard) and run but the motor is heading downhill

 

well i just sold the car and when I used to drive it, it drove perfect and boosted hard never had any problems with it.......but not as i just sold it the car isn't boosting anymore and the kid said he got a compression check and those were the #'s. but the car starts fine, idles perfect, had tons of power and never lagged. so its really hard to believe it needs a rebuild........

 

If we're talking psi when you say 100 and 80, yes, the motor is damn close to death, and IS dead by Mazda factory standards.

Minimum Mazda spec is around 700 kPa which converts to approximately 102 psi. So, the numbers you're quoting are around 690 kPa for 100 psi and somewhere in the mid 500 kPa range for 80. The car will run, but will probably stall with the AC on and sometimes when you come to stopsigns. No disrespect intended, but if I were the buyer I would have paid for a compression check before laying down my money, but that's just me.

 

Odd, my factory service manual says 85psi. You might wanna check that number again...102 psi is perfectly fine, though not 100% strong.

 

Sorry guys,

RotaryResurrection is correct. Both numbers are within spec, albiet low. Minimum spec in checking my service manual IS 6.0, not 7.0 as I had suspected. My apologies for the misinformation.