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Starting to get a loud hum or whine on cold startup, alternator?

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russ g

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Registered
1990 300e 2.6
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129 Posts
Discussion Starter • #1 •
It only happens in the morning on 1st startup of the day and just turns off after initial warmup (maybe a minute or so) Seems to be coming from the area of the alternator. It's kind of a loud metalic whine. Any suggestions?
Thanks!
Russ
 
300se126

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Registered
1990 W126 300SE - High Mileage Award
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995 Posts
#2 •
Sounds like a smog pump issue to me. Mine hasn't been plugged in for years and it is just fine - and passes emissions. There is only one wire lead to the pump - follow it out of the pump and up towards the passenger's side fender until you see a connection, then disconnect it. Just make sure you drive it around and get it nice and hot before going in for emissions, or plug the pump in for emissions testing only.
 
DarkOneSK

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Registered
1985 500 SEC, 2005 E320
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1,294 Posts
#3 •
my money is on the smog pump as well.
 
russ g

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Registered
1990 300e 2.6
Joined
·
129 Posts
Discussion Starter • #4 •
Thanks guys, will check out smog pump. BTW, no emissions testing in Iowa so no worries!
 
300se126

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Registered
1990 W126 300SE - High Mileage Award
Joined
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995 Posts
#5 •
russ g said:
BTW, no emissions testing in Iowa so no worries!
Click to expand...
Seriously? Need a roommate?
 
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