w114 motor makes a low moaning sound at idle, only when cold - Mercedes-Benz Forum

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post #1 of 2 (permalink) Old 09-17-2011, 06:52 AM Thread Starter
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Date registered: Feb 2011
Vehicle: 1969 W114 250 /8
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w114 motor makes a low moaning sound at idle, only when cold

Only when first starting up on a cool morning, and only at idle, the motor on my w114 makes a moan, or groan type sound that is intermittent. I haven't a clue where it's coming from (I stuck my head under the hood and tried to pinpoint but failed), it sounds like some kind of suction or opening is happening. A bit hard to describe in words but an almost human (!) like groan, lasting a second or two, then stopping, then repeating, until warmed up. Again, only at idle. Also, I should mention the motor itself runs really well, starts up every time, etc., and the compression on all 6 cylinders was checked very recently and all those numbers were good.

Any thoughts? Is my w114 possessed?

1969 W114 250 /8
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post #2 of 2 (permalink) Old 09-18-2011, 08:54 PM
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Date registered: Mar 2011
Vehicle: 1971 250/8 sedan with 80 K miles. Driven only in Summer.
Location: Vancouver BC Canada
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Take off the airfilterhousing and look how easy the chokes open up when starting, or just turn your key to on and watch the chokes open evenly without hesitation. Try some WD40 as a quick fix. Also listen for a vacuum leak while you are at it. Good luck.
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