Recently it has begun to sound like I have a flock of birds chirping under my dash when I turn the heater on. This is not fan related as it occurs at all fan speeds but does not change pitch.

Could this be a vacuum leak..or is it "normal" for a 1987 201?

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Dana Linscott
Vegoil converted truck...vegoil converted 1987 190DT, 300 series next.

http://vegoilconversions.netfirms.com/

Is it temperature related? My 87 SDL does the same thing, but only when it is really cold (well, by OK standards) and only for about 15-30 seconds at startup. Mine also has no dependence as to if the fan is on or not. My guess was maybe auxiliary water pump, but that was only a guess.

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Keep everything as simple as possible-but no simpler--Albert Einstein

This occurred not long ago on my '87 124. I would hear a funny, med/high pitched noise from under the dash that would go away in about 5-10 minutes as the car warmed up. I ultimately traced it to my sampling motor. I took the motor out (on the right at the base of the A pillar, behind the glovebox on the 124) and cleaned/oiled the end bearings. I've had no noise now for over a year.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

It may be temperature related...but I won;t know until it warms up again. It began making this chirping sound when it turned very cold (-20F to +20F) and the temps are expected to stay in that range for a few more weeks here..MN.

I replaced my aux pump this fall...old one was seized...along with my climate control module which was fried...probably from the pump siezing.

It does not seem to sound like dry bearings...but I would look into that possability If I knew where my 190s sampling motor was..or if it has one.

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Dana Linscott
Vegoil converted truck...vegoil converted 1987 190DT, 300 series next.

http://vegoilconversions.netfirms.com/

I have heard this type of noise with bad speedometer cables, on older M-B's (and other cars for that matter).

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94 E320
71 350SL

If you have an auto climate control (pushbutton unit like on all the later 123s and all 124s) you almost certainly have a sampling motor. It's probably behind the dash on the passenger side (at least it is on the 123 and 124) and you may be able to trace it back from the intake. The intake is a small 1/2" square grate on the center of the dash on the 123 and on the light unit above the mirror on the 124. The 123 has a hose that runs from the intake behind the glovebox to the motor. On the 124 the hose runs down the A pillar. Your 190 probably has a system similar to one of those two.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold

Pulling out my trusty Performance Products catalog...what great "exploded views".. I see I have a "temperature sensor" on the light unit above the mirror and a "temperature sensor fan" in the dash about where the chirping sound is coming from.
A hose connects the two running up the passenger A-pillar.

I will remove and lube this as soon as I can get aheated garage space. This sounds like the most likely cause of my 190s' chirping dash.

Thanks!

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Dana Linscott
Vegoil converted truck...vegoil converted 1987 190DT, 300 series next.

http://vegoilconversions.netfirms.com/

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