A bit of a mystery

[mike murphy]

Any budding Sherlock Holmes out there?

I've got a 325i convertable which I've had since new from 91. Only 80,000mls.
I've been loosing coolant, so my BMW authorised garage replaced the radiator, this didn't help. So then they said that the head gasget needed replacing, again no result so then they said the head neaded re-skiming. This didn't help. So I took it to another garage and they said that THEY wanted to skim the head. Again this didn't help.

Obviously I'm down a lot of money and I still have the problem.

I can't see any external leaks, and the consumtion of coolant seems to be getting greater.

Now for the strange bit. Recently I drove some 300 miles armed with gallons of coolant . after about 20 miles my coolant warning light came on, but as the miles passed the temperature gague didn't move.

After the journey I had a look at the coolant tank and saw that there was still some showing. When I released the pressure, the remaining coolant dissapeared.

Any advice thoughts or just hunches would be greatfully recieved.

Thanks in advance.
Mike.

[frank3]

Check for signs of leaks around the thermostat housing. I understand that they're prone to slow leaks that burn off before the coolant hits the ground.

More importantly, I would not use those mechanics again...a lot of money for mis-diagnosis.

PS - This is posted to the wrong forum...you'll get better response posting this to the correct 3 series forum.

[sp0rky]

when you open the cap, the coolant does go back into the radiator and "hide".

Are you sure its not just your coolant level sensor telling you its low when its really not??

[Torque]

i think you should have checked and/or replaced the hoses before doing anything. they do crack on older cars...

[Winged Nut]

Your radiator cap is causing the problem. When the coolant is hot, the coolant expands into the overflow tank, but when the coolant cools, the radiator cap's valve is stuck and doesn't allow the coolant back into the radiator. Replace the rad cap and everything should be fine. It would be a good idea to check the water pump for leaks at the weep hole. (Look for dried coolant traces.)

[GnnSk8]

has it overheated? If it did it could hav warped the cap or another part of the engine causing it to leek or burn up the coolent. Overheating in BMWs is vey bad w\ the "high-tech-ish" engines

[karab95]

Yep bad indeed... check the radiator cap or look for unusual leaks from the exhaust pipe.