John McLaughlin wrote:

How did the apex seal break? Was this a turbo engine over boosted or was
it mis-timed causing detonation?

I'm not sure yet. I have a 1990 n/a engine (in a GXL) so I don't have the
joy of overboosting. Thus far, I've observed the following symptoms:

I believe I had at least one leaky injector - I was getting quite a lot of
fuel in the oil. I was changing the oil every 1000 miles. Should have fixed
the injector.

I was running with a bad TPS for a couple months. The full range sensor was
triggering the CHECK ENGINE light at idle (this controls the oil metering
system). The CHECK ENGINE light would go out off idle, but now I'm
suspicious that the oil delivery may not have been right.

The side seals on both sides of the rotor were stuck in places and the grooves
were filled with oil. Bad oil seals? I know the car sat for 1 to 1 1/2 years
before  I bought it, running infrequently. At that time the compression was
good, but lately I had started to use more oil than usual.

Lastly, when the engine popped, I had revved it close to the redline (it was
a nice spring night), went to shift to second and heard a great POP when I
let the clutch out.

How should I go about reconstructing what went wrong? If it was an oil
problem from things I should have fixed, will there be some telltale signs?

Lastly, did Mazda use gaskets on the oil pan? Mine had only sealant.

John McLaughlin

Well sounds like you had plenty of warning John. Perhaps this was a case of a 
worn three piece apex seal rolling out of the rotor slot mentioned by
Dave Atkins. Dave likes one pieces seals and I agree. What do the good 
apex seals look like as far as wear is concerned? Check the wear between 
the sides of the apex seals and the rotor slot. This wear could be accelerated 
if the cheap plastic oil injection line was broken on that bad rotor. A common 
problem with engines of that age. Check those oil lines folks.

Mine had a gasket but I notice they recommend a bead of red silicone rubber.

What kind of crankcase oil were you using and how often did you change it?

The leaky injector could have been introducing enough fuel to wash away
the injected apex seal lube. One great thing about mixing apex seal lube
with the fuel. The more the fuel the more the lube.

Paul Lamar
 
The Aircraft Rotary Engine Newsletter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org