I have a rebuilt 13B engine in my 87 RX-7. In runs great but sometimes after I turn it off it won't restart unless it sits for an extended period, like over night. The last time it happened, I was being towed home and after going a few 100 yards, I put the car in 2nd, turned on the ignition and it started. There is no one near where I live who knows much about these engines. One mechanic who has had some experience with them thought it might be that the 'seal' on the rotor weren't seated correctly. He suggested mixing some transmission fluid with water and injecting it into the running engine through a vacuum line.

Has anyone had this same problem and found a solution?

Thanks.

 

hot start fails = seal issues.

you said you got the "rebuild" engine, who rebuild for you and do you know what has been replaced ?

 

It was a rebuilt engine from ATKINS Rotary Engines (via ATK Noth America) in Puyallup, WA. They specialize in providing rebuilt Mazda engines. When I bought it I didn't find anything negative about them on the internet. I don't know specifically what has been replaced. I assume all the moving parts, seals, gaskets, etc. I returned my engine for a core return. I assume the eventually rebuilt my engine and sold it.

 

I just got an email back from ATKINS Rotary Engines. They say it is because it is flooded. That doesn't make sense to me as the car was running, then stopped, then wouldn't start. How would the engine get flooded?

 

that part alone is enough to tell that the engine has low(er than usual) compression.

only way to find out is do a compression test.

As for the ATF thing, its good/bad, good thing is it might free "stuck" seal/springs and help the engine start, bad thing is that it's not so great to the coolant seals.

Atkins is a very well known company in the rotary community, they build lots of engines, Im not trying to judge their ability but, last time at 7 Stock, I saw them rebuild an engine, at the final compression test, the value between 2 chambers were out of spec. I forgot the guy's name but he said "everything is ok". I was standing there and ....

 

The engine in general is very prone to flooding. In addition, it is even more prone if you drive the car a short distance and shut it off, without letting it warm up to operating temperature (aka short start).

Letting it sit overnight will not fix a flooded rotary engine.

http://www.rx7.com/tech/unflood-fc.html

 

Was the engine shut off when it was still cold (not fully warmed up)?

It will flood because the stock computer puts in a lot of fuel when the engine is cold.

Rebuilt engines tend to need some miles on them before they can reliably/consistently start.

 

Seeing how it was just rebuilt, its probably a compression problem.
Rebuilt engines start up great when cold, but when the engine is already hot, and you try to start it again it wont because metal expands when hot. In a fresh rebuilt with new apex seals and used housings, it will take some time for the apex seals to conform to the used housing wear paths. Some people say it takes 20 miles, some 1000 miles. If it was new housings and new apex seals, the chances of low compression is rare.

 

Not if its built right

 

telling you, just do a compression test.

it will tell if your engine is healthy.

and do it only when its HOT.

This is also why I will not buy a used engine(or anything used) unless they can tell me what has been replaced/reuse.