SteveNick

I've been reading this thread with interest as this coolant episode happened to my car yesterday for the first time. I had the car out for a 30 min run, used the boost a couple of times, nothing very strenuous and when I parked it back in the garage the turbo cooler fan ran for the usual 30 secs or so. I went in the house , fun's over for the day.

For some reason I came back out and heard water hitting the floor, stuck my head under the car and thought for sure I'd blown a rad hose. Blue coolant all over the place. There was enough volume I stuck an oil pan under it. Then it quickly stopped. Jacked it up pulled and determined that the leak was coming from higher up in the engine bay so I figured it had to be either the expansion tank or a hose in the turbo cooling plumbing.

After the car cooled down I started it and let it get up to temp and there were no leaks so I'm concluding since there was no turbo plumbing leakage, it must have come via the expansion tank.

I'm mystified. This car has never leaked a drop in the 4 years I've had it. It's completely stock so it's not seeing excessive boost pressure. I just had it out again tonight for about 20 - 30 mins and no leaks, water temp gauge reads as per normal, just a shade under the first increment. I did not get on the boost however. I was just seeing if I'd have the same problem if the car is driven gently. I made a point of observing the expansion tank after I shut it down tonight and everything appears normal, no sign of boiling in the tank.

What really bothers me is I had the car out a week earlier for a 1 hour + run and used the boost several times and nothing happened.

I'm not operating at the same technical level as you folks but I thought you might find another example helpful.

Jon Schepps

StoneGrey,
When they can catch me, I'll consider it!
The emabarrasing part is, Pete has always said "the easiest way to pass a 944 Turbo is to wait for it to blow its head gasket, then whiz on by".
jls.

Perry 951

I won't say it NEVER gets lower.... but it hasn't yet. The level it sits at is just barely above the front nipple. I'm sure if I AX'd it like that, I would probably need to bleed the system when I was done.

Songzzz

Jon, I have been thinking all night about your problem... maybe the water pump thermostat not installed correctly, i.e. reversed.

Perhaps you can try driving the car hot and feel the air out of both cooling fans, if the one on the right (facing the car) is blowing hotter, something is up.

Instead plumping coolant out from block to the radiator, the water pump is circulating coolant in the block, hence causing coolant to boil, pressure increase and coolant will be forced backwards, in reverse order via the water passage on the head.

Just my wild guess, someone please correct me if it is wrong....

MachSchnell

If the t-stat was backwards, however, it would overheat and the gauge would go up, but it seems like most of us who are having the problem are running at primarily normal temps even when the problem is occuring. I'm getting so concerned with this that I'm considering the possibility of needing to o-ring down the road with consistant 18psi usage...

MySwiss

Well. I think we have a common problem. Cause my new 951 does exactly the same thing. Once it goes down to the minimum mark, it stays there forever. I've also tried all of the above tests, and my conclusion, is to live with it , like this.....the car never overheats, no matter what the conditions are and it never likes more coolant then the minimum mark.

Songzzz

Let's keep this thread going until someone figures the cause.

Jon Schepps

Uh, let's drop the backwards t-stat discussion.

Could be that for cars with greater than stock boost, things just run hotter and the coolant level has to be a bit lower to compensate. But this would only hold if the car was driven on high boost a lot. I suspect that's not the case with many of you.

So I pulled my head and I see signs of blow-by from at least 2 cylinders on the head side. Cylinder tops and gasket surfaces look perfectly clean. Note this head gasket only had less than 50 miles on it - a run up and down the street after it was put on, then some test laps at the track. So the cylinder head was still very clean, and the blow-by areas are pretty clear. I'm having it checked for flatness and pressure tested.

Here's a photo-

Jon Schepps

How does one attach a photo? I used the Attach File box, but didn't seem to work.

NZ951

I run at higher boost now. I just filled my coolant (with antifreeze) levels up. I filled to the max mark, then after 5 mins of driving, the expansion tank was empty. I filled with more water back to the max. After another trip it was empty again. This happened 4-5 times. I thought I had a leak. I filled it again, the water now almost white (not green) as the water had been purged so much. I open the hood after another run and the resivour level is at max. And it has stayed there for 2 weeks now. No movement at all. I was going to start a thread titled the case of the disappearing water... but saw this. Not sure if any of that is of use, just my experience.

Jon Schepps

NZ- Did you do the bleeding procedure when you first filled the coolant tank? If not, that would explain the disappearing coolant.
If you did bleed the system, when you say the tank emptied, did you happen to notice if the bottom of the car on the drivers side was wet? That's where the overflow tube dumps.

Jon.

NZ951

Jon, no I did not do a bleeding procedure. What is it? No water through the exit tube obviously...

Jaak Lepson

NZ ... check out clarks garage for the procedure. There is a 12 mm bolt that need to be loosened and it is found to the right of #1 intake on the upper hose housing.

What I did was raised the passenger front of the car, screwed in a 8 mm grease fitting with a 1/4' clear hose (IIRC) that I ran back to the overflow tank. Turn on the heater and start the car. Run it untill the coolant flows with no air bubbles.

Screw the bolt back in and you should be set.



JClarks Garage Link here

Jaak Lepson

Songzzz

Perhaps its not a problem afterall. It seem to happen to everyone. I did a check on my fresh 3L motor, fill up coolant over the max. mark. Drive it hard at 1.1 Bar..... stop and I found the coolant missing, splashed out of the overflow tube.

Peckster

What's blowby on the head side?

The only time my car loses coolant, out the overflow or otherwise, is when the headgasket is bad.