I just purchased a 1985 12a rotary, for $250.00. The guy that I purchased it from at the salvage said that the engine had no compression. When I get the engine home, I will test it to see if it is carbon locked. But if he tried to start it and this is what he found, chances are that it is not locked. My question is if it is the compression, would the engine have to be rebuilt, or is there something that I can do to get the compression back. This is my first go at a rotary engine. Thanks inadvance Johnny

 

Depends on what is actually wrong with it.

If its just carbon locked from sitting,then lubing the hell out of the insides and CAREFULLY rotating the engine backwards can break it free with little/no damage.Some people use ATF,others use MMO.....its all the same idea,soften the carbon and crud so that it doesnt gouge the delicate internal running surfaces of the engine when you turn it over.

If the engine was overheated,overevved,or beaten to death,then its quite likely that the internal chrome plating is wasted or the engine threw up an apex seal,or both.In that case,the only cure is a tear down,and rebuild.It might still run in this condition,but it wont run well,and continued running will just furthur wear out potentially reusable parts.It can be costly if many of the parts are ruined from a catastrophic failure,but a "plain" worn out rotary can be properly rebuilt using nearly all used parts.

An easy test is to just pull one front sparkplug and crank the engine.If the whooshes are consistant,then that chamber is good.Then,pull one rear plug and check the rear chamber.If it alternates between strong and weak whooshes,then youve got a bum engine.Failure of 1 apex seal will result in the loss of 2 of the working chambers,or 1/3 of the total engine.Sometimes apex seals will get gunked up and stick,so after the whoosh test,before you remove or scrap the engine,remove the exhaust manifold and visually inspect all 6 apex seals through the exhaust ports.If you have a mirror and flashlight,you can also get a good look at the chrome plating on the bottom of the housing.

 

Thank you Steve, I will do exactly what o you told me to do. Johnny

 

Why are you posting up multiple threads with the same question? Trochoid had already covered this with you on another thread.