Big_Ern

I have an '83 GSL 12A that blows a lot of white smoke for a few minutes on startup. Drive it, let it sit for 5 mins or more and it will blow quite a bit of white smoke when I start it again. It blows more smoke the longer it sits. It is loosing coolant as well

A couple weeks ago it threw a belt and over heated quite badly before I knew what happened and was able to get a new belt (temp gauge was broken). I have had the stock nikki carb off recently to rebuild it as well (starts and runs great with the rebuilt carb!)

From research and general knowledge I'm thinking that the over heating probably blew some internal water seals.
What do you guys think?


I have read that a lot of people use Alumaseal with good success on a 12A blowing white smoke to fix the internal water seals

What type of alumaseal do you guys use? the liquid or the powder? Any advice for its application?

Big_Ern

or it could possibly be the intake manifold gasket and coolant seal O-rings... is there any way to test which one is the problem?

7aull

iTrader: (2)

Sounds like classic case of blown internal water O-rings Ern. White, sweet-smelling smoke is coolant vapor blowing thru the exhaust, & suggests that the failed seals are now permitting water into the combustion chambers. I am not aware of ANY fix for this other than pulling the motor, break it apart and (at the very least) replace the O-rings.

Usually another sign is, when looking into the Rad, you will see traces oil (which floats) on the coolant.

Ironically, as long as you can start the motor, the seals sometimes (as in your case) re-seal with the temporary expansion of the housings and the car runs fine. Until you stop it. Eventually tho there will be so much water in the combustion chambers that it will simply not ignite. Meanwhile there is a real danger of running low on coolant (since its going out the tailpipe!) and over heating the engine - again. Right now you might be lucky and only have damaged the O-rings. But continued use could start to heat-damage the aluminum rotor housings; then you will be looking at some serious Coin for repairs (I will point out that you can no longer buy NEW housings.)

The O-rings themselves are not that expensive. Of course, one always faces the "Well, since I am in there, what else should I renew at the same time?" Presuming things like the apex seals are up to spec. then you are essentially doing a mild rebuild. Lots of folks here have done these and it requires few special tools, one being than a good torque wrench. From personal experience I have found the various Rotary Engine Rebuild tutorial DVDs (Mazdatrix's is my fave) are worth every penny of the $30-ish you spend. Simple motors, but there is particular secrets and "gotchas" you want to avoid. OE shop manual is also helpful.

Best of luck-

Stu Aull
80GS
Alaska

Big_Ern

thanks for the info Stu.

I am quite mechanical and have done complete rebuilds on piston motors and always do all of my own work on vehicles, but unfortunately I have some other projects on the go in my shop and do not have the room, nor cannot afford the down time with my rx7 right now to do a rebuild on it.
I have heard good things about using Alumaseal on 12A's with very good success rates whereas it doesn't work very often on 13B's. So I'm hoping that I could use this to get me by for a couple months until I have the time to rebuild the motor

I fixed the temp gauge and it barely even gets 1/3 up the gauge even after long hard driving, so I am not too worried about getting further damage in that regard.

I have not noticed any oil in the rad and the oil on the dipstick always looks clean too.

It did not seem to blow white smoke immediately after I overheated the motor badly. In fact I didn't really notice it blowing bad until after I had rebuilt the carb which was a week later. So I'm maybe wondering if I could have missed a seal there. Or quite possibly it is just coincidence as I didn't drive it much in that week before rebuilding the carb as it ran like crap and the floats always stuck.

It only puffs white smoke (coolant burning) upon start up after it has been sitting 5 mins or more. The longer it sits the more smoke and the longer it will blow smoke before it clears up. I pulled the plugs today too and they all looked normal color from regular use, so I don't think coolant is entering the engine while it runs or the plugs would be steam cleaned (similar to a piston motor with a blown head gasket).



I do agree that when I do the rebuild "oh while I'm in here I may as well do this and that too" to make it a complete rebuild and quite possibly I will be porting the motor while I have it all apart too
Thanks for the tips on the Mazdatrix rebuild dvd as well.

Big_Ern

Are there any coolant seals below the carb that I could have missed or messed up replacing? My carb kit had a number of o-rings that I never found a place for so they didn't get used.

TimWilbers

iTrader: (1)

There are two O-rings between the intake manifold and the rotor housings. But they did not come with the carb rebuild kit I purchased.

They can leak and coolant will be sucked into the intakes.

Big_Ern

I have read about those intake gasket o-rings, however they wouldn't have been touched during a carb rebuild since the intake manifold never came off, so I wouldn't expect them to be the problem. I could be wrong though.

erick31876

iTrader: (8)

Coolant seals

DivinDriver

iTrader: (15)

Hopefully just coolant o-rings; if allowed to overheat too much, you can also warp the rotor housings, which is a higher-dollar fix on a 12A - - no new 12A rotor housings left, excepting people's private hoards.

Only way to find out is via tear-down and measurement.

Big_Ern

I put in a tube of alumaseal powder this morning. Let it idle 20 mins then took it for a drive. I'll see when I start it up later if it puffs white smoke badly still. Hopefully this will help tide me over until I have time for a full rebuild

Kentetsu

So, how did this turn out? Hopefully it worked as well for you as it did for me.



.