I'm considering rebuilding my 12a engine and was wondering if this is a major project? I removed the motor with no problem and I have rebuilt standard V8 engines. I have tons of rx7 experience, but none with rebuilding the engine.

The engine leaks steam from the front rotor into the exhaust after the engine heats up. This engine has a lot of power and runs great, but this steam leak could develop into something more serious.

 

Did it ever overheat?

 

No, I started getting concerned with the steam coming out of the exhaust intake, so I parked the car. The engine runs great and does have a lot of power. I purchased a rebuild kit from Atkins, so I'm ready to start
the rebuild process.

 

 

Sorry, steam coming out of the exhaust manifold!

 

Might be a coolant leak from your intake manifold (bad o-rings). The coolant could be drippin onto your exhaust manifold and then burnin up...

FS

 

I replaced the intake manifold gasket & both O-rings and the steam problem continued. I'm sure the steam was coming from the exhaust manifold.

 

Steam would come from there if coolant was put onto the manifold. Therefore, something is leaking. If it isn't your o-rings then I think it might be coming from your housing. Could they be corroded enuf to leak coolant?

FS

 

sit, i was stumped on that one too

 

yah, i would bet its the o-rings or badly carroded intake manifold...
or when you replaced the o-rings you might have pinched one

 

So, you guys think I pulled this motor for no reason. I replaced the intake gasket and O-rings twice and had the same results. The flow of steam never changed. After the car would run 20 or 30 minutes a steady stream of steam would rolling out of the exhaust manifold. It never did impact the performance of the engine. I figured that maybe a O-ring or something blowed. This engine has approximately 16000 miles.

 

OH, I forgot to mention that on the front rotor with the exhaust manifold removed the exhaust hole is pure white. I don't think that is normal.

 

when you cranked over the motor with the exhaust manifold off did any water /coolant come out?

if the port was white, you do have a problem...

 

I never attempted to run the engine with the exhaust manifold off. I removed the exhaust pipe from the manifold and steam did roll out. I'm sure I have a engine problem, so my question is how complicated is the rebuild of a 12a? I have a rebuild kit on the way with a 12a rebuild video.

 

Get earmuffs and try running it.

Are you loosing coolant from the cooling system?

If you have v8 rebuild exp, I assume you know the symptoms of a blown head gasket. Blown coolant seal has the same symptoms.

 

Yes I do, this engine was losing a small amount of anti-freeze, so I assumed that was my source of steam. I attempted to get an inspection and the inspector told me the meter was off the scale.

 

man if you already have the rebuild kit, and the engine is out, i say there is no question, rebuild the thing...even if its not the orings, really simple rebuild compared to the v8,

 

its a piece of **** to rebuild... only problem is that if you find things like your haousings are rooted.. then the big $$$ are needed to get new ones.

The steam is a good one... if you have no exhaust leak then the steam is being driped onto the manifold. meaning theres a leak somewhere else. when its apart getck all the housing o-rings and check very carefully the grooves they sit in, looking for small cracks/splits

-james

 

Ok, thanks for the information.

 

the 87 Rx-7 I had for a short while (like 6mo.) had the same problem. The engine that was in it to begin with had a bad oil seal and smoked like a freight train. So, I went the junk yard and got another engine. Ran fine the first 1,000mi. or so then it did exactly what you explained. After it warmed up, it burned antifreeze. The guy at Rotary Revolution here in Tennessee told me that it is the rubberband-like seal between the water passages and the cylinders. He said they (can) go bad...

Pretty sure that was the seal he was talking about anyway... Nevertheless, a rebuild should fix the problem. Atkins has a video that I've heard is really good on rebuilds and be sure to use Atkins apex seals!

 

I ordered the video from Atkins and a rebuild kit. However, I did not order the apex seals. This engine was rebuild a few years ago and has only 16000 miles, so hopefully the apex seals are OK. Other than this leak the engine runs great.

 

port it while your at it

 

The word on the street is that you ALWAYS use new apexes. I asked the same question on my rebuild, but everyone seemed to agree for the price, it's not worth the risk if the seals have more than 100 miles on them...

Just for the record, a lot of people seem to be using RotaryAviation's apexes, including me, they seem to be working okay so far.

/my .02

 

Ok I got to ask, what difference does 2mm or 3mm have on the performance or the life of the engine?

 

12a's use 3mm regardless, its not an option