Yep, I don't know if you noticed my other thread about my Fluidyne failing and making my car overheat, but I *think* I'm beginning to see some of the symptoms associated with blown coolant seals. For the past 2 days, it is a little more difficult to start (ie, takes a second or 2 extra to crank, or starts then stalls until you start it again). When it does start, it isn't really a "rough" idle, but more of a very weak/low one. The only good thing I saw from it is that it DOES sound like it did before, just a lower idle (no misfiring, backfiring, etc). When it eventually warms up, its great, idling perfectly with little to no change, between 1050/1100 rpms.

All of this combined leads me to believe that the culprit is bad coolant seals... anybody else agree? Thanks! ~A-Rod

 

I would think you would be seeing white smoke out the exhaust with a failing coolant seal. I thought that was always the sign to look for. Your car might just be adjusting to the colder weather

 

In my experience with damaged coolant seals, I never had a problem starting the car when cold (aside from all the smoke the car put out while burning off the coolant). The issues I had were hot starts.

 

Are you losing any coolant? If not, I would not suspect coolant seals...

 

Mine are bad now and I've been nursing it to get to this winter.
I wish I could be more positive, but initially I had similar symptoms as you've described. It progressed over the course of a year or so to some occasional stumble/miss on cold start-up (along with a little steam/sweetish smelling exhaust). I emphasize occasional...not EVERY time. My coolant tank level then began rising and over time coolant level warning would go off. Also, like you, it runs like a top otherwise.

 

Well I just put the replaced radiator yesterday, and I am still in the process of burping the system. After we had eliminated most of the air, it would still have the same strange problem. I read on another "coolant seal failure" thread that the vehicle is difficult to start because of less/more pressure in the coolant system than the motor (or something like that, I can't remember completely, I just know the bottom line was no coolant=difficult to start). The exhaust is somewhat white, but I'm almost believing that it is because of how ridiculously rish I am running. There is no sweet coolant smell whatsoever, it just smells like raw gas. I've started it in cold weather before, and it didn't start up quite like it did the past two days.

I'm putting it away at the end of the month (possibly sooner), I just want to know if I should be saving to rebuild the motor or not.

 

White, sweet-smelling smoke = coolant
Black smoke = fuel

However, on startup, there will be condensation in the exhaust itself, so some water vapor might be present (white "smoke" with normal exhaust smell)

 

Right... but what I find interesting is that after almost 2 years, people have always told me the same thing... any time I get on it, white smoke comes out of the exhaust. This was back when I had my cats in and everything. The car was compression tested in June (not sure if bad seals= bad compression), but everything was fine. I'm just a little concerned as to what the sudden problem is... and I highly doubt it is the cold weather. As mentioned before, the car was started and driven in colder weather than temp of the past two days has been.

 

Coolant seals typically leak through a very small spot. So during driving the coolant seeps out very slowly or not at all since the combustion chamber keeps a higher pressure than the coolant passages, driving engine gasses into the coolant rather than coolant into the engine.

Now the car is warmed up and the cooling system is pressurized. If you stop the car the pressure in the engine goes to zero and the residual cooling system pressure squeezes coolant into the engine. Depending on how bad the leak is and how long it's sat hot, it can be hard to start and will blow coolant smoke. Ditto if you shut the car down and start it the next day. So that's how it can affect cold starts.

Dave

 

Ohhh, ok, that makes sense... thank you for the informative post!

But what about at WOT? Why have I been seeing whitish smoke for almost 2 years/15,000 miles now?

 

I always assumed bad coolant seals make hard starting when hot, not when cold.

It seems like your car is adjusting to the cold weather. When was the last time you replaced your plugs/wires?

My car idles funny now because its cold out but smooths out when its getting warm. Last time i changed my plugs was in may. But i hardly drive the car so im sure the plugs are already caked.

Im gonna change them again soon.

 

This is exactly what happened to me. I tried to convince myself that since I never saw any white smoke, or smelled any coolant burning, that the coolant seals were not my problem. I knew I was losing coolant slowly, and the system wasn't pulling coolant back from the overflow tank, but I figured it was a leaky hose (I ended up replacing them all). I also had problems with my temp gauge reading erratically due to air in the system (the sensor was at the highest point in the TB coolant line). I tried in vein to "burp" the system, but after an hour or so of driving, I could hear the air burbling around in the heater core again. When it got to the point that the system would still be under a huge amount of pressure, even after sitting for days, I knew it was curtains for the seals. Thankfully my car never overheated as a result of this.

The bottom line is this. There are 2 easy ways to tell if you actually have a bad coolant seal: Pressure test the system, or get a hydrocarbon test. You can have these tests done just about anywhere, and its really the only way to know for sure.

 

Maybe a stupid question, but could the location of the coolant seal failure, relative to the intake/exhaust/combustion "chambers" ultimately affect the specific symtoms? For example, if MADDSLOW is reporting a little steam during WOT, could his coolant seal failure (if it's a failure at all) be nearest the intake? And in that case, rather than the combustion chamber pressure keeping the coolant out, the vacuum of the intake would tend to bring it in? Unlike mine, which based on symptoms of coolant steam only briefly following cold start-up, would be nearer to the combustion chamber.
Of course in both our cases, we would tend to loose vacuum in the coolant system as the engine cools, leaving coolant stranded in the overflow.

 

I never thought about it that way, but it seems to make a lot of sense. I guess in my case, my leak would be closer to the combustion side if that is true....

 

Yes. As I understand it, most coolant seal failures happen in the region by the combustion side. The symptoms I describe relate to that scenario.

I can't comment on how often other locations fail or what symptoms that results in.

 

Not really sure what you're getting at here. At WOT, there is no vacuum present at any phase of the rotor's orbit (the intake is pressurized by the turbo). Letting off the throttle would cause a vacuum in the intake phase, though. Am I missing something here? (seriously, not being sarcastic)

 

like 1quik7 might be the weather, my motor does the same in winter

 

I haven't had an FD in so long that I forgot what coolant smells like. Seems like if you're an FD owner, you can smell that stuff just by memory lol.

Hope it's nothing serious...best of luck to you!

 

Umm... what?!

That's just great, my next question was going to be "why is it difficult to start after I park for 5 minutes and come back"...

I've continued to attempt to burp the system, and every time so far has required a little bit of coolant (only have performed this twice). Hoping eventually I will open that AST and see coolant in there, rather than air...

 

Doh! I hadn't thought of the pressure from the turbos in the intake during WOT. And I didn't take it as sarcasm. I was just thinking out loud, trying to figure why some symtoms of a coolant seal failure are constant and others are different. Probably just boils down to the size/severity of the failure itself.

 

Another way to tell is to look for little champagne type bubbles in the coolant. Take off the cap near the water pump area (when the vehicle is cold), start the car up and look for little bubbles in the coolant. If you've got a coolant leak it might be visable that way. If the coolant just starts backing out as the car heats up and there isn't any bubbles, my guess is that there isn't a coolant seal failure.

Obviously, a true pressure test would be the best way to tell; however, if you don't smell it, it doesn't smoke, and you're not seeing coolant leave the system over a short time, then I'd guess the problem is something else.


It's also been my experience that rotaries are just smoke hogs. They smoke when they're f*ed up and when they're in perfect running condition. Unless it's major smoke, then that just sounds like 80% of every rotary car I've ever seen. The other 20% smoke like crazy.

 

Usually really badly shot coolant seals will make cold start difficult due to coolant seeping in the housing overnight causing the plugs to foul. As far as the "white" smoke you have seen over the last 2 yrs I would assume is just light oil smoke coming from the turbo/turbos. Its hard to make out the difference between light grey/white smoke in your rear view as you are going WOT. You will never mistake back fuel smoke for the other two and if the turbos finally "let go" that too will be noticable. Pull your leading plugs and clean/dry them thoroughly. Put them back in and let the car sit overnight, the next morning inspect the plugs to see if they are wet from coolant.

 

Did everyone one miss this? If not losing coolant, then coolant seals are ok. Pretty simple

 

I've filled my AST 3 times so far, with no leaks under the car.

 

At least in my case, coolant loss has been really minor. I rigged a little plug for the top of my overflow and once a week or so, I use my shop compressor to blow the stranded coolant back out and into the AST and filler neck (being careful not to blow up the plastic overflow bottle).
In the past six months or so, I've only had to add about a pint of fluid. Probably the same amount I've "burnt" occasionally when it stumbles on cold start, up but not very noticable unless your watching it closely.