siguy2k

iTrader: (3)

So i did a compression test with a piston compression tester and im getting one bounce and 2 nothing with the valve open. If i leave it closed its 60ish psi. I still get three swooshes with the plug out. Is this a stuck side seal? I couldnt find the thread i was searching for and am tired of looking.

Syritis

iTrader: (2)

this method for testing is highly inaccurate but betting then nothing. leaving the valve close will only give you a reading for the face with the highest compression. if you only getting 60psi on the best face then i'm sure or youre over estimating the intensity of the wooshes.
typically if only 2 faces of the rotor are dead then the apex seal between those faces in broke or stuck.

jkep21

iTrader: (12)

^Isn't it the other way? As one apex seal is responsible for sealing two chambers? I'm still kinda learning but I think this is right.

AMRX7

Apex seal will lose two chambers, so you will get one higher reading or "better" sound from open plug hole. Side seal will get 2 higher readings since only lose one chamber.

-Andy

siguy2k

iTrader: (3)

Why the three even whooshes then with the plug out?

RotaryEvolution

iTrader: (30)

0psi on 2 faces is one dead/stuck apex seal.

a side seal will still give a marginal compression reading. side seals rarely fail, FYI.

whooshing sound from the engine doesn't mean jack. that is why they call it the "poor mans compression test".

Carlos Iglesias

iTrader: (6)

Bingo. BTW, here is what a partially sticking (front rotor) side seal looks like on my post-build initial compression test (sorry of the oversized picture):




For what it's worth, the Mazda spec in this regard is no more than 20 PSI difference between any two rotor faces.