Ok, so here are the cliff notes of what I did before this happened.

1) Drained old coolant from radiator.
2) Added new 50/50 mix of Prestone to filler neck by t-stat.
3) Waited a while, topped off coolant as air bubbles purged.
4) Repeated step 3 several times.

I did this Friday afternoon, and had to help a friend move this weekend. Shortly after I did it, I ran the car with the cap off to insure I wasn't getting any exhaust in my coolant. I was receiving some bubbles coming up by the filler neck, but nothing excessive, and nothing that smelled like exhaust. So, when I got home Sunday night I decided to run the car for a little bit to warm it up with the new coolant. Well, when I first started it, it felt like it was running on 1 rotor. It was sputtering, so the first thing I did was go to the back to get a good smell of the exhaust to see if it was burning coolant. Nope, no sweet smell to it at all. I jumped back in the car to let it run to see if the idle would smooth out, but then it started bellowing A LOT of exhaust out the tail pipe. Again, I ran to the back to smell for coolant, but it was just very potent exhaust. Then, I got back in the car and was about to shut it down when I noticed some plumes of smoke coming from the turbo location. After that, I immediately shut it down. I then went over to where it was smoking, and took a big whiff. I thought for sure it would be coolant burning, since that's the only system I had messed with. I thought maybe a coolant line ruptured going to the turbo. Nope, it smelled just like exhaust...No burning coolant there. Then, looked on the floor for any leaking coolant...Nope, nothing there. So, after putting everything back together and sitting there scratching my head, I decided to check the coolant level again. Surely if it had just burned a bunch of coolant it would be down. To my satisfaction, the coolant level was visible in the filler neck. So, since everything appeared to be ok, I decided to give it another try. I go to start the car, and it fires right up, idles where it should smoothly, and is not smoking from the turbos. And here's where I have a few questions.

How high should the coolant be exactly in the filler neck? It wasn't all the way to the cap. In fact, it was below the line that runs to the AST, but still visible in the bottom of the filler neck. The only other weird symptom I had was my temperature gauge, but I would guess that it was just air purging from the system. My factory coolant temp gauge got up to normal before my aftermarket gauge moved at all. Of course, they normally move synchronously. I chalked that one up to there being air around the aftermarket temperature sensor, and then as soon as coolant got to it the gauge went right up to the normal location (~180 degrees).

So, my theory as far as why there was smoke coming from the turbos is that since it happened when the car was bellowing exhaust maybe some of the exhaust was seeping out from the turbo location? I mean it was REALLY bellowing exhaust like crazy, and it didn't smell like coolant at all. (I've smelled my fair share of burning coolant in the past, and this was not it).

Any thoughts? The car seems to be fine now, is not burning coolant, and is idling fine. I'm just wondering what could have caused the weird startup condition after draining/filling the coolant system.

Any help would be much appreciated!

 

Leading coils arent firing would be my very first assumption. This exact same thing just happened to me

 

Interesting hypothesis...Leading coils don't fire, thus not burning the a/f mixture completely (well, as complete as it burns in a rotary anyway), which leads to more unburnt fuel in the exhaust.

It definitely fits the symptoms! Bad idle, sputtering, bellowing exhaust...

Also, another thing I thought of...It was EXTREMELY humid here over the weekend, and it wouldn't surprise me if a lot of moisture condensed in the exhaust. Then, when I started it, it decided to bellow out.

Anyway, thanks for the help! That certainly is a possibility.

 

Also, my question still stands regarding the coolant filler neck. How full should it be? Mine has never been full all the way to the cap. Should I be worried?

 

You shouldn't be worried. Fill it all the way to the top. You may still have some air in the system, and may have to do this several times.

 

Thanks Adam. When I got home from work, I filled it again and started the car. It didn't take a lot of coolant, but you could tell some air had purged out. This time it started completely normally, but again the Defi water temp gauge was a bit sluggish to indicate temperature. Again, I think this can be attributed to air in the system which is being purged out.

Thanks again for the responses guys!

 

Make sure to squeeze the radiator hoses in between your fillings. That will help force out some air.

 

I was trying, but the damn things are so hard to get to! Is there something I'm missing?

 

keep on filling it and pulsing the hose,eventually it will be good to go

 

sometmies at my work when we do drain and fills on cars they will run pretty crappy when the air is still in the coolant system, normally when there's a really big air pocket itll almost sound like something is wrong internally, then all of a sound a big burp eruipts and everything is good again.

my coolant never stays all the way to the cap on my fd, but it also never goes lower then level its at, like if i top it off to the cap, it goes back to the level it was at after a short drive, and then stays there.

kevin.

kevin.

 

Thanks again guys!

 

It also REALLY helps when purging air from the system to remove the throttle body coolant hose, as this is THE highest point in the cooling system. I have simplified the burping/purging process immensely since I learned this little trick (from fellow Forum members of course!).
Your coolant should stay absolutely FULL in the filler cap by the water pump housing.
I can take my cap off any time and the coolant is always RIGHT THERE.

 

Thanks bajaman. Also, I believe the TB coolant hose is where my temperature sensor is for the Defi gauge...It would make sense for there to be air there, hence why the gauge is a little sluggish to react.

 

I have the same damn problem! I always had my coolant up to the filler cap until i did a radiator change. After a drive i leave the car to cool and check the coolant level. The AST is always full till the cap however the coolant in the filler cap is always low again (just below the line that runs to the AST) so i have to top it up. This problem is driving me crazy. Does anyone knows what's happening? (Ps the platic tank is also always full).

 

ive done 2 flushes on mine, it always seems to take awhile to get all the air out of the system.