HELP! need advice on damaged rotor and chamber
 

I need some advice on how to proceed with an engine problem.

I recently purchased a 1985 RX7 from an aqaintance. The vehicle body was in great condition, inside and out, except for a missing font bumper. The engine and tranny had been removed. The whole vehicle was $300. He told me that he had a problem with the engine and was going to rebuild it. After he took the engine and tranny out, he found another vehicle for sale that ran well. He decided to sell what he already had. He explained that he thought the seals had gone bad on one rotor.

I did not know anything about Rotary Engines, but thought this would be fun to work on and learn with my 18 year old son. When we got to disassembly of the motor, I noticed that there was compression in one chamber, but not the other. I also started to become concerned because when i turned the engine by hand, I heard something scraping. :confused:

Anyhow, after removing the Clutch and Flywheel, we took off the first section of engine and could get ant the rotor. That is when I cringed! :eek: The rotor had deep gouges all over. The seals had been destroyed. I also discovered that there were at least three different spot on the inside wall of the chamber that had chunks of metal protruding from it. It should be completely smooth. I think somthing got into the chamber either from the intake port or was left in there on a prior rebuild. The chamber wall is scratched to hell and back along with the rotor. :(

The question is this. Is it possible to buy just those parts of the engine that are damaged, or do I need to find a replacement engine? Used, rebuilt or otherwise.

Any suggestions would be greatly appreciated.

Hard to answer your question without seeing what the rest of the motor looks like.
Since you don't have any experience with RE's you'll have to take extreme care here. I highly recommend a trained eye otherwise you'll put this RE back together only to have it blow in 5k mi.
The least you'll want to do is have the housings lapped and cleaned. Is there any evidence of oil starvation? How much carbon build up on the other Rotor? They get to a point where they simply cannot be used again. Same for your Rotor and Side housing. There's so much to this. Since the motor is apart I recommend a "full" rebuild kit. The Eccentric Shaft is vital here too. Is it warped? Can you post some pics for us to look at?

I guess I forgot to answer your question..
Yes, you can replace just the damaged parts BUT you'd really be doing yourself a dis-service. It's a cheaper way of doing it but in the long run you could end up paying more.. I've seen motors that were half assed grenade after a few thousand miles. On the other hand you may find 1 or 2 people who have been lucky doing so. Keep asking questions and you'll be ok. Post those pics!

no, you don't have to buy them new and putting parts from another motor in your car is not half assing it. they are all the same between the same motors. just keep an eye out for either a blown motor or the parts you need on parts trader and e-bay....... you should do a full rebuild though and replace every seal in the motor. also i have blown a motor and cause very extensive gouging. it is from something (a seal) breaking off inside and having a joyride. front and rear rotors and housing are also interchangable, so if you find an engine with the same rotor blown then you will be okay.

I didn't say anything about buying new parts, parts from another motor or anything specific about the "half assed" comment. Read carefully here.. Without getting into a forum debate.. I'm saying make sure the rest of the motor is in a condition that they can be used again.
One more thing if you're going to go so far as to tell someone that "parts" are interchangeable then why not tell him which years and motors.

RX7Bandit, if in doubt call your local Rotary shop. Peace!

Yes you can replace the parts you need. There is some slight difference in rotor weight and they are stamped with letters so its easy to match up what you need without throwing the entire motor out of balance.
I think you can also get a used rotor housing. USe a Mazda rebuild kit with all needed components. Use the factory manual to get all your clearances and specs correctly. The apex seals will need to be cut to fit. This might be the most challenging part. As I am not an expert I cannot comment further on that. But its nothing you cannot figure out. Everyone has to learn and this is how you do it.