maaaaackle

iTrader: (1)

Hey guys, I'm currently working on my project; an NA S4 FC. It's been sitting for a couple months and I only recently drove it for about 10 - 15 miles. When I came home I was worried of the car overheating cause I've read horror stories so I went ahead and replaced the thermostat, flushed all the coolant, replaced the hoses and the whole nine...

When I went to go start the car back up, it was running fine but there was that dreaded, sweet smelling, white-ish smoke coming from the back of the exhaust. Now I know that that only means one thing: time to rebuild but I drove the car around my block and the smoking completely stopped. No smoke. I let the car idle for a couple minutes to see if the smoke would come back; but nothing, it was clear...


Am I safe? Or is it just wishful thinking.

misterstyx69

iTrader: (142)

Keep an eye on the coolant level seeing you just attended to the system.
Coolant can spill in the darndest places and you can smell it even though there isn't a leak.You get it on the exhaust and the smell will linger.
Only careful observation can tell if it is ok or if you have to go further.
A leak would be an obvious sign that it needs to be addressed.

maaaaackle

iTrader: (1)

Darndest placest to the point where it would even be burnedout through the exhaust???? Thanks for the input though! Im just a bit concerend is all

Sgtblue

iTrader: (16)

White smoke....steam, is USUALLY a sign that coolant is being consumed in the combustion chamber. That USUALLY occurs as a result of a coolant seal failure. When you shut off a hot engine, the cooling system is still pressurized. That pressure forces a bit of coolant past the failure and into the rotor housing as the car sits. When you start the car cold again, that bit of coolant is burned, resulting in the steam. A lumpy, stumbling idle on initial start-up is also USUALLY associated with this. But the steam and idle clear up after a few seconds as soon as the coolant is cleared out. And typically there are no more outward symptoms during operation of the car as any coolant is consumed as fast as it enters. But on the next cold start, the cycle repeats itself.

I agree with Styx, watch it closely over the next couple of weeks and get the cooling system pressure tested. If you become convinced that it's a failed coolant seal, don't wait too long as coolant sitting in the seal grooves can corrode and damage the iron...making it unusable for a rebuild.

sp0ngebob

iTrader: (1)

steam is also a byproduct of combustion so dont be that alarmed if you see a little steam. it matters how it smells and what your coolant level is doing. watch your overflow tank too. it could be slowly replenishing your radiator and you may not notice that the coolant is disappearing until that overflow tank is empty

maaaaackle

iTrader: (1)

The smell coming form the exhaust is definitely coolant. :c


Better start saving now...

Sgtblue

iTrader: (16)

Agreed. But actually in my experience it's more common for the coolant reservoir to overflow rather than go dry. Because of a coolant seal failure, the vacuum that's formed by an intact cooling system is lost. Coolant isn't drawn back out of the overflow reservoir as the engine cools, and eventually it overflows.

From an earlier thread FWIW..........

Originally Posted by Sgtblue:

A coolant seal failure is a common problem....at least in the FDs of which I'm familiar. IMO it's the price for forced induction. Boost is power. More power= more heat= more stress. NA rotaries have the problem, but AFAIK, not nearly as soon as the FDs.

Still, before doing anything, make sure you have a failed seal. Besides the 'Champagne test" these are all the symptoms I can think of... but no single symptom by itself is confirmation. Many symptoms could be from other causes. However the more symptoms/conditions you have in combination, the more likely it is a coolant seal failure.........

*Stumbling idle on cold start-up that clears up quickly. The combustion chamber is fouled with coolant. As soon as it's purged or burned up, your car will run fine until the next cold start.
*Slightly sweet exhaust smell, especially on start-up. See above. Coolant is being burned and it has a distinctive smell.
*"White smoke" (steam) on cold start-up even in warm/hot weather. See above.
*A coolant over-flow tank that is over-flowing. This will usually result in a puddle under the car near the right front...the area of the over-flow tank. When coolant gets hot it expands and that's what the overflow tank is for. But with a failed seal the natural vacuum that forms and pulls that coolant back out as the engine cools down is lost. That leaves that coolant stranded in the tank and eventually it overflows.
*Coolant loss that isn't explained by a puddle on your garage floor. It's being consumed by the engine and going out the exhaust.
*Spiking temps that seemingly recover on their own almost as quickly. Air pockets in the cooling system allow steam to form. That will cause temp spiking. This is different than a rising temp just after a period of hard boost. It can happen as your steadily cruising down the highway.
*Boiling sounds after shut down even shortly after properly "burping" the system. See above.
*Failed coolant system pressure test.
*Failed test of coolant for hydrocarbons.
*Unusually clean plugs, or wet plugs if you pull them right away after starting the car. (Sometimes you can even smell the coolant)
*One or more episodes of serious overheating in the car's history regardless of miles. (from what I've read, 115 C./240 F. seems to be the critical number for OEM seals to begin to degrade)
*An otherwise well maintained and cared-for FD approaching 100K miles or so.

As for a band aid, some have used one of the many "Stop-Leak" coolant additives to give them a bit more time but use at your own risk. While it's not anything that will leave you on the side of the road, a failed coolant seal can easily lead to erosion/rust/pitting of the coolant seal grooves in the irons. That can cause a junk iron and make the inevitable rebuild more expensive.

maaaaackle

iTrader: (1)

Thanks for the input guys. I took a look at the car and it seems to be coming from the back of the engine and the exhaust.

I read the FAQ's on the issue and tried the tests. I pulled the EGI 30A fuse and cranked the car and coolant wasn't splashing everywhere. I cold started the car and pulled off the rad cap on the thermostat neck and it was not bubbling at all.

???


However, my idle is a little bouncy. Heres a video. Is that indicative of a doomed coolant seal?


Idle_zps309b152d.mp4 Video by lksdf | Photobucket