Cognac
Hello . Sorry to be posting a problem before I have even had a chance to introduce myself, or put a picture up. I have had my Z4 for 4 weeks. 2003 2.5i convertable. Drove it 600 miles from the Uk to were I live in France without any issues. For 2 weeks the Coolent level warning light has been coming on intermittantly. I have checked it constantly and at no time has the level been low. ( indicator in expansion tank sitting up high ). So I assumed its just a sensor problem. Day before yesterday I had been out for a short drive, left it on the drive running for a minute and when I came back the temp gauge is in the red with the red light on and a buzzer. So Switched her off and I've got fluid dripping out on the offside front. Just had a look tonight and I can see coolant sitting on the under tray offside. But I have no idea were it has come from. I don't know this car and have never owned a bmw before. I have looked at the posts regarding split expansion tanks/ top, bottom hose fix's etc. I'm not sure whether something has let go and then its over heated, or is it a stat issue and then its just ejected it out of the vent on the expansion tank. Any suggestions or advice would be appreciated. Panicking new owner at the moment. I guess my next move will to be top up the expansion tank, let her run and see if i can see were its coming from. What coolant should I use ? The expansion tank is bone dry at the moment, float right down. Thanks in advance. Paul
re coolant leak
- Thread starter w1ndsurfnut
- Start date
Sounds definitely like an expansion tank issue. The tank is a push in figment at the bottom of the tank. When pressure builds up at full temp this can be enough to force the tank loose and let the coolant escape onto the floor panel. Use standard anti freeze mix solution. If there is a split in the tank you should see this leak after some time without the engine running. If it is a pressure issue then will show it self when at full temp. Best of luck.
Just wanted to say a big thank you to the forum for the heads up on this. As csm180 said it's the expansion vessel. There is a tiny hole on the corner which only lets go when the system pressures up. So obviously I need a new expansion vessel. If any one has done this before what other parts would you recommend to change at the same time if any, and were is the best place to get it online. In the mean time I will try and find any previous posts that might help.
Re coolant leak (UPDATE)
So I got the parts for the problem. New expansion tank and cap, new coolant level sensor, and new thermostat for the auto transmission. read a post somewhere that this piece had been a problem. Sorry There are no photos, getting the expansion vessel off was a complete pig. When it did come of half the thermostat came with it. I am now trying to get the rest of it out of the bottom fitting. Trouble is every bit of plastic I try to get hold of to pull it out is as brittle as anything. keep you posted guys.
So I got the parts for the problem. New expansion tank and cap, new coolant level sensor, and new thermostat for the auto transmission. read a post somewhere that this piece had been a problem. Sorry There are no photos, getting the expansion vessel off was a complete pig. When it did come of half the thermostat came with it. I am now trying to get the rest of it out of the bottom fitting. Trouble is every bit of plastic I try to get hold of to pull it out is as brittle as anything. keep you posted guys.
This is the thermostat for the automatic transmission that sits underneath the expansion vessel. As suggested in posts/forums this parts is normally broken as well, and in my case it was. The new unit is on the top of the shot. I have no idea what happened to the cap part on the broken one as that was nowhere to be found. The small bits are what came if in the process of trying to get it out. Its O-ring again and was stuck fast. The plastic was extremely brittle. I believe its been suggested that this failed part causes an over pressure in the system which causes an old expansion vessel to fail. Mine had cracked in the corner.