90 rx7. if the apex seals are worn does usually mean its time for a rebuild? dont know mush about rotary engines.

 

Think of it this way.( I hate to refer to the Other engine..).
If your Piston rings are Non-existent,would you get compression?

 

You can get a good idea of the engine's health by doing a compression test. The only way to tell if the apex seals are worn is a complete tear down of the engine and careful measurement of components. If they're out of spec, the only repair is to replace them. There will be some other seals that have to be replaced during the rebuild, so that's a few hundred in 'soft seals'. You may find other parts are no good as well. That is why the price of an engine rebuild varies greatly. I doubt you'll get someone to rebuild the engine for under $1500, but it can be done for much less if all the other parts are good. Unfortunately, you'll never know until the engine is already disassembled.

I'm assuming this is regarding a car for sale so here's a few links regarding buying an rx7:
How To Buy An '86-'92 Non-Turbo RX-7
How To Buy An '86-'92 Turbo RX-7

 

Well you could have good apex seal perhaps replaced by a previous builder, but good seals do nothing if the rotor housings have excessive chrome flaking or gouges.

Short answer, yes worn apex seals= lowered compression time to rebuild and inspect.

 

Check compression, anything over 85psi is considered "good" and anything over 100 is great. Although you can drive on a motor that has good compression, but anything worse then that and you should get it rebuilt. Hopefully you don't have to dump money into a rebuild. Good luck!
-Steve

 

That being said, you want to make sure the compression does not vary greatly from face to face. For example

Front rotor face 1: 90psi
Front rotor face 2: 88psi
Front rotor face 3: 92psi

Rear rotor face 1: 91psi
Rear rotor face 2: 81psi
Rear rotor face 3: 88psi

Small variables are acceptable, but a greater one like in "Rear rotor face 2 there's too much allowable pressure differential.