Some guys here (who do not have any rotary experience) are saying that we need to periodically do a leak down test on an aviation rotary to monitor the life of the seals. They sugggest the piston style leak down test of flowing a known air supply pressure thru a small ofifice, and then into the spark plug hole, and monitor pressure downstream of the small orifice. I have been fooling with rotaries for 22 years now, and I have not heard of anyone doing anything more than a cranking speed compression test. I also know that apex seals seem to seal better when the rotors are spinning, and this leak down test is done statically; the rotor is held still.

Has anyone here done this style of leak down test on a rotary before?
Has this style leakdown test every provided useful information to you?

I am trying to be open minded about their suggestion, but I feel like they are trying to apply their piston head mentality on this little rotary.

PS the engine manufacturer does not recommend this leak down test

 

If the test could somehow damage the engine, according to those in the know, then don't.

If it is safe for the engine, I'd go ahead and run it anyway. If it shows some accurate infomation about the engine then its a useful test and should be performed to monitor wear and diagnose problems.

 

It's been two days now, and no one has said they did a leak down test on their rotary, so I must assume that a leakdown test is a very uncommon diagonstic procedure for a rotary.

 

i found a bulletin in the 78 bullitin book about using a leakdown tester to find bad water seals, but thats it

 

A leak down test gives a more detailed view of valves and seats in a psiton engine.

When you use a high tech rotary specific engine tester that corrects cranking pressure readings for the RPM the engine is tested at you are doign the most accurate test possible for a rotary engine, the figures derived (pressure) are a function of leakage past the sealing elements and there is lots of data around to determine if your engine is healthy or not for your particular year model etc.

Make sure you use the correct equipment (rotary specific) and if your using the old tech Mazda testing unit correct your compression readings of the test paper to take into account the cranking speed the motor is tested at.

Disconnect the fuel pump and makes sure there is no fluid around the seals when you do the test (crank it over after running it dry)... And you will get the true state of health of your engine.

Leak down test = NO.

 

j9fd3s - thanks, that makes sense.

Rice Racing - it has been several years ago since I conversed with you on the Mazspeed 1st gen forum. Nice to hear from you again, and thanks for your comments.

Thanks all - Speedturn