johnnyg

This has probably been asked and answered a hundred times, but I searched and couldn't find anything...

What kind of compression numbers should I be seeing when turning the engine over by hand? I think I remember seeing a figure of 30 PSI.

opelbits

iTrader: (5)

Not sure, but they should be fairly even. I've turned a motor over by hand (with the plugs in) and could feel the compression buildup for each rotor face. That is a good sign. If it spins real freely, the seals have pulled back. Doesn't mean it's bad, but it will need some help.

johnnyg

I'm getting good "swooshes" with no plugs, but it sounded like the rear was weaker than the front. I just bought a compression guage and it's showing even pressure between the back and front at just over 30PSI (cumulative). I'm just hoping that this number is good!

opelbits

iTrader: (5)

You might try a little ATF in the leading plug holes. I find that those neat little 'syringes' (plastic plunger things, got one from my dentist, but Walgreens or a decent drug store should have them) work great from squirting a controlled amount of ATF into the plug hole. Put a piece of vacuum hose about 2" long on it.
Use about .5cc in each hole for each rotor face (three in each hole, but rotate the motor for them). This may give you a good seal and help build more compression.

Incidentally, when Mazda does a rotary compression test, they have an formula that adjusts the compression reading based on how fast the motor is spinning. Ideally, 250 rpm is what they call for. The faster or slower the rotor is spinning will force the seal out towards the rotor housing and provide a better seal.

But you already knew that since you asked the question, right?

RotaryEvolution

iTrader: (30)

as long as there is no pauses in the pulses it should be ok.


there is no figure for compression whiile rolling the engine over by hand, some people are stronger and care less about their fingers than others.