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Old 01-08-2019, 12:39 PM
Andyz4 Andyz4 is offline
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Location: Orlando, FL
Join Date: Mar 2018
Posts: 300
Mein Auto: 2006 Z4 3.0si
Originally Posted by GaryDZ View Post
2007 Z4 3.0i

I cannot get a break with this coolant system.* About 4 months ago an ASE mechanic friend (works mostly on US and Japanese cars/trucks) replaced the Expansion tank because of a very fine crack/leak.* A month later I had another leak and he replaced the thermostat, plastic housing and hoses. I did not do the work---so this is the best description I can give.*

For the past 3-4 days I have been smelling a faint coolant smell.* I do not see a leak (no fluid on the floor of my garage) and the temp is running fine with an hour drive to work.

Today my interior windows (Front and sides) started fogging up pretty bad. I had to drive with the defrosters on.* After the fog cleared, it came right back when I turned it off.

For a “normal” car I would think it might be the heater core… any ideas or advice?

Thanks for any help.

Gary DZ

Yes heater core does seem likely. You can check under dash for moisture with a good flashlight and also hose connections under the hood at the firewall. But if mechanic overfilled the expansion tank (which is easy to do -- ask me how I know), it might be cracked again. To test, set the heater to full hot and take the car for a drive to fully warm it up. Now switch it off and with the hood open, listen for steam escaping at the expansion tank. (Also under the dash). Give it at least 5 minutes to fully heat soak. You can also use a length of fuel hose as a stethoscope to help pinpoint any source of leakage. Hope you find it. Andy

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