DSMblue

I replaced the radiator this past weekend to try and resolve last potential known leak source. All went fine, pressure bled system, works fine. Checked coolant level this morning, I was down about a quart! No big leak on garage floor, all hoses either replaced or verified OK, water pump has no leaks, no white smoke from exhaust. Any ideas on where the coolant is disappearing to?

marky522

I recently did a headgasket on Knfeprty's car, his car had the same problem for 8 months, coolant disapearing and no signs of a leak, and no smell from the exhaust, it even passed a compression and leakdown test, hot and cold. then all of a sudden it let go and filled a cylinder with coolant.

Mark

MAGK944

+1 headgasket. Does the coolant system hold pressure?

V2Rocket

check your oil for 'milkshake' frothiness

MM951

Does it loose a quart and stay there or does it constantly loose coolant?

Have you checked the oil cooler?

FWIW, I've noticed both of my previous N/As, my moms N/A, and my 951 all seem to like their own amount of coolant and will loose an amount and then remain constant at a level. With both of my N/As I would be about 1/3 way up to the max line on the reservoir when cold and my 951 will spit anything out over the min line --- cold engine coolant levels -- all cars reservoir would be a little less than 1/2 full when warm

joes

Be real carefull many engines have been lost due to coolant filling up the cylinder and the piston coming up on compression stroke and busting the liner during a hot restart.

DSMblue

Oil cooler is OK, seals have been previously replaced there. No coolant in the oil, or vice versa. I am going to watch it over the next few days and see if it continues to lose at that rate, or if it was just a one-time thing. I hope it isn't a head gasket, that equals $$$ to get that done right, not to mention the car is out of commission for quite a while. I will post back once I have more data.

knfeparty

Yeah I had all sorts of gremlins.

I have fuel-locked a 2-stroke engine before, so when I came back from that fateful arby's meal in SC and turned the key and it went "whuuuu----" without the lights dimming....I knew I was screwed. I checked the spark plugs and whaddya know it's full of water. I think the engine is okay though. It did fine at VIR the other weekend.

I never experienced any smell or anything, I just knew that I could not keep air out of the cooling system and that it loved to overflow the coolant on a regular basis.

MAGK944

The reason I am saying this is that I had a similar issue on one of my 944's. The coolant in the tank would go down occasionally, especially when I checked it in the morning after a spirited drive the previous night. I had no visible leaks anywhere, no coolant in oil or oil in coolant. I drove it around for about a year, just occasionally topping it off with about a quart every week with no ill effects.

Once I tried to remove the cap very carefully straight after a long drive and I noticed there was no pressure there. I checked several times after and still no pressure in the cooling system. But I could not see any leaks and it never overheated.

I eventually had to have my head gasket replaced (timing belt/bent valves - another story) and then I found the problem. There was a small tell-tale trail of coolant following a path along the gasket to the outside, just below the exhaust manifold between 2 and 3 cylinders. It was a tiny leak, probably evaporated before it had time to drip to the floor. But just enough to lose pressure.

Headgasket replaced and no further issues since.

Funn944

Step 1. remove shoes

Step 2. sit in passengers seat

Step 3. are your socks wet ?

Yes ? . you found your leak

No ? . continue your search

StoogeMoe

Well, hopefully it was an air bubble (and quite a big one) that worked itself out. Are you sure you had the heater valve all the way open when filling the coolant?

Just keep an eye on the level to see if you're still losing some.

If it is a head gasket, you can sometimes read this situation by looking at the plugs.

peanut

if compressive gasses are pressurizing your coolant system then your header tank cap could be venting it whilst you are driving.