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Thread: Coolant Loss
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Old 01-15-2020, 07:24 AM   #8
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Join Date: May 2017
Location: USA
Posts: 113
My Ride: 330XI
Originally Posted by jmo69 View Post
Puff of smoke on cold starts could be valve guides, if the smoke is blue. Condensation and coolant would be white, excess fuel would be black. Coolant pressure test might be in order.
Thank you for the suggestion, but the loss of coolant is the issue and thereby pretty much assures the smoke is coolant. The culprit is the question.

I'm not losing oil, or getting misfires from undetonated fuel which would cause black smoke. It's puffy white... Valve guides are interesting in any event and if so, I'm sure would also include a visible show on plugs when removed. Could it then also lend to rough start as oil is burnt off plugs...? But again, wouldn't explain the loss of coolant with no other visible leaks evident. Which brings my thoughts back to HG.

Just deductive reasoning... Should be fairly nice this weekend which will allow me to dig in. Compression test first, if good, then leak down or I'll rent the coolant pressure test kit and go from there.

But to assuage my fears... How bad is a HG change on the E46/M54 engine? Is HG fail typical or is it the head itself? Again, no overheating issues exist (since I've owned it). I've seen a lot of mention on the heads which of course is a concern. And with no untypical oil consumption for it's age, there was some, but replacing all the CCV fixed that. Is a full rebuild even worth it, or just replace HG and run it until fail? Swap engine later if it happens? These are the scenarios running in my brain, lol.

Last edited by Cooolone; 01-15-2020 at 07:25 AM.
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