My family campaigns 2 IT-7 RX7's. Have been fun reliable cars for a couple of seasons now.

Yesterday though at Carolina Motorsports Park I overheated one of them (steam was coming from under the hood). Temp was around 220 which is about normal operating temp for that car (other car runs 180 but has aluminum radiator and new electric fan).

The car ran fine with no indication of problems other than the steam. Pulled into our garage space and let it idle for a few minutes to try to avoid having it soak too much, but I also wasn't sure how much water was in it at that point so I didn't want to keep running it too long.

Later when we were ready to pull it on the trailer it would not fire. Turned over with the starter fine. Tried starting fluid which did not ignite. Continued attempts to start eventually resulted in coolant under the car apparently coming from the exhaust.

I'm a mechanical engineer and know my way around piston gas and diesel engines pretty well but I'll admit I know very little about Rotary engines other than the general theory..

1) how would coolant get into the exhaust?

2) Why would the engine run fine with no indication of problems, but then refuse to start after 45 minutes or so? Apparently something having to do with heat soak, but that still seems odd to me.

3) Assuming the engine needs to be rebuilt, we have 3 cores. What's the best way to evaluate which one is the best starting point?

 

Cracked iron or failed water jacket o-ring due to overheating. 220 degrees F is pretty hot if you are really pushing the car for long periods of time.

You can compression test all the cores by bolting up a flywheel, bellhousing and starter. But if you are planning on rebuilding anyway, just disassemble them and inspect the parts.

 

Where are these O-rings located and how would we replace one?

 

The only way to replace the water o-rings is with a complete rebuild, the o-rings are what seal the rotor housings to the side irons and keep coolant out of the combustion chamber and out of the oil pan.

 

You should grab a copy of the Factory Service Manual from:

http://foxed.ca/foxed/index.php?page=rx7manual

Mechanical engineers should know to check the manual first.

This video will give you a good idea of where all the major parts are during disassembly:

http://www.youtube.com/watch?v=W1MXfs_Srs4

Here's how I clean engine parts:

http://www.youtube.com/watch?v=U5A5q61bzRI

And finally, here's the full process of reassembling the engine:

http://www.youtube.com/watch?v=ijJeUk_GqiI

 

Thanks for the responses... the cars are in the care of my dad and brother, and I think they have some manuals for them, but I do not, just trying to do some research first.

Thanks for the tips!

 

Any thoughts on rebuild vs. buying running engine? Any reason to build an engine with stock internals required for IT7? Anyone know of good engines for sale?

thanks

 

Read this thread before you make your decision. I think your chances of success would be pretty good: https://www.rx7club.com//showthread.php?t=930506


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