My '86 240DL is having some minor coolant issues. But they smell bad. sometimes.

Lately, when its warm(er) outside now that spring is approaching in Southern Ontario, my car starts to reek inside the cabin of burned coolant. This happens only in stop-and-go city driving. The coolant level has not gone down a noticeable amount and its been happening for a few weeks. Today, I idled the car for 15 minutes and tried to find leaks both inside and outside, to no avail. No smell either. This was right after my wife drove the car through the city for a while. She said it didn't smell at all while she was driving it today, though it is closer to freezing that yesterday. Yesterday it really put up a stink, but I didn't have time to find it.

So, anyone have a guess? If not, I guess I just have to wait till its warm and then try to hunt it down. Certainly a weird leak. Oh, and turning the heater on/off doesn't change anything.

any advice or idea is greatly appreciated.

Nate Gundy
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'86 240DL sedan, 260K miles, M46, K cam, 25/23mm sways, 260 front and wagon rear springs; http://valvespringcompressor.weblogs.us/