NZ951

So I got home from the gym, found a drip drip leak of coolant on the left hand side near the rear tyre, quite a puddle.

I open the coolant res cap, hear a whoosh, coolant level is ok. I start the car up again, and there is no leak?

I drive to work, and there is no leak?

Im assuming the cap is buggered? I have a 2001 model.

318touring

Crack in the tank?

NZ951

If it continually leaked, yup... not the case though. Unless the pressure expands the crack... I guess its one or the other.

Zanzibar Red 996

Keep a eye on the (fill markers on tank)
They can be easily misunderstood

Barn996

Replace with the newest cap. If that doesn't work, I'd suggest you have a cracked coolant tank. I had similar symptoms before I replaced my tank(with a slight crack).

Macster

If the cap has an earlier part # (-00 or -01) replace the cap with a newer one with a part # of -02 or -04 IIRC.

My WAG is the coolant tank has a crack.

Do a pressure test. A hot one.

Drive the car around town to get the engine up to temp. Leave the A/C off. But you want to drive the car enough the radiator fans come on.

Back at your driveway with the car positioned for easy access by a flat bed tow truck operator raise engine rpms to say 1500 and hold
until the radiator fans come on.

Then shut off the engine.

Get out of the car and wait.

When the hot coolant comes gushing out of the bottom of the coolant tank call the tow truck company and have the car taken to a shop for a new coolant tank. Be sure the new cap is moved from the old tank to the new one.

Gofishracing

You know the coolant line fittings will be failing as well.

fpb111

more likely on GT3 & Turbo engines.

Gofishracing

Investigation probably on all Mezger engines....NTHSA - Tank cost $150 plus labor but that''s the surface. The cars are aging as well.

NZ951

I do the work myself, no labour. Its only replacing a tank not rebuilding an engine with special tools... dear oh dear.

Gofishracing

yes. PIA job. Just the surface. Rubber hoses getting tired etc.

NZ951

hard to call that just the surface, rubber hoses are a consumable item... the reason? Rubber continually cures, based on temperature or pressure, so it just harder and less flexible.

NZ951

Pressure tested, no leaks, replaced cap.

Now it still leaks... not through the overflow either, this is weird.

318touring

Your water pump is fine?

Hose clamps not tight enough?

NZ951

The pressure test would have revealed any lose clamps I would think... its a real mystery! No issues with the water pump, its leaking around the coolant tank...