Coolant leak healed itself? Ambient temp related?

When I pulled my 645 out of winter storage there was a decent puddle of coolant underneath it, enough to cause me to drive immediately to someplace where I topped it off with straight water. I then lost about 1 qt over the next few weeks (little bit under engine each time I'd come out to garage) when the temps here in Michigan were still pretty low. Since it has warmed up, I'm not losing any, and there's none under the engine when I come out to it each day. It did seem like I didn't lose any last year until when it got cold, right before I put it away.

Any ideas why I'm only losing it when ambient temps are low? I NEVER get a coolant (sweet) smell in the car.

Once your coolant level is reduced percentage wise, it will not leak as much. If you add more coolant, it will start leaking again.

Originally Posted by HerbP

Once your coolant level is reduced percentage wise, it will not leak as much. If you add more coolant, it will start leaking again.

Refilled to top, no leaking since.

Probably has something to do with metal contracting and expanding due to temps. There are way too many places where coolant can leak for us to speculate what the source is.

Next time it leaks pull out a flashlight and try to find the leak. You can also get a much better view by removing the lower cover which is held on by 10 screws.

Yorgi - Do you mean the plastis shield at the bottom of the engine bay, or the valve covers (decorative)?

I mean the front undertray. When you remove this you get an excellent view of the hoses and pumps from under the car.

If you see fluid on the ground and you cannot find the source by looking from the top of the engine, you will probably see the source by looking from under the car. The undertray is held on by 10 captive quick-release screws (when you undo them they stay attached to the cover) so removal is fast and painless. If you have ramps it will take 5 minutes to remove.

Hi Yorgi~

I am leaking fluid due to that small hose that lies across the top of the radiator. It connects to a curvy hose that is connected to the expansion tank. Its skinny and long like about the size of the wooden stick on those fourth of july flags. Its secured on each end by small silver pinch brackets......

do you know the name or part number for this coolant line and do you think its an easy fix? Your knowledge about these cars is a blessing.

Thank you for any info and advice.

Parrish

Originally Posted by Blaknificent

Hi Yorgi~

I am leaking fluid due to that small hose that lies across the top of the radiator. It connects to a curvy hose that is connected to the expansion tank. Its skinny and long like about the size of the wooden stick on those fourth of july flags. Its secured on each end by small silver pinch brackets......

do you know the name or part number for this coolant line and do you think its an easy fix? Your knowledge about these cars is a blessing.

Thank you for any info and advice.

Parrish

That is the vent pipe / overflow hose. Where is is leaking?

If a pinched clamp is leaking it can be replaced with a standard stainless steel screw-down hose clamp. Use a screwdriver or needle nose pliers to loosen at the crimp. Then cut off the clamp (tin snips) or remove the rubber hose and pull off the clamp.

The vent pipe sells as one unit for ~ $57 if you need a new one. Part# 17127542540

Once again yorgi is right....It is called the vent pipe very easy to install

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Yorgi! Thank you very much for your help. I'm proud to be a part of this forum with such knowledgeable members. This car is affordable ONLY because of diehard bimmer fanatics like you and countless others. If i ever hit the Powerball, you can pick out two brand new bimmers for you and the Mrs!