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New alternator now engine hesitation?

Old Jul 25, 2010 | 03:36 PM
  #1  
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New alternator now engine hesitation?

Put a new aftermarket alternator in my CLK after the original gave up at 73k miles. Now I'm noticing a slight hesitation when initially accelerating from idle speed. It's slight but I notice it.

Another indication something is not quite - the AC fan is running will drop in speed slightly (but I notice it) for a split second at the same time - right when I initially push the gas pedal. Otherwise everything seems to be running fine and all the electrical systems are working normal.

Any ideas? Seems to me like voltage or amps are dipping when engine (and alternator) start to speed up. Could it be something to do with the voltage regulator?

JW
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Old Jul 25, 2010 | 07:19 PM
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Anyone who can offer advice, much appreciated.
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Old Jul 25, 2010 | 08:22 PM
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04 CLK 320 > CLK32K
Probably because it's aftermarket. The car needs OEM alternator
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Old Jul 25, 2010 | 08:40 PM
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Originally Posted by dynomite05
Probably because it's aftermarket. The car needs OEM alternator
Why would the correct aftermarket alternator make any difference? It's the same specs and totally designed to be interchangeable with the OEM alternator. It's not something that was modified to fit. It has the correct + terminal connection and the same electronic plug to fit the original connections. Same voltage and amperage rating as the original.
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Old Jul 25, 2010 | 08:46 PM
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I hear ya but MB's are like that. I tried using an aftermarket MAF a while back, had to change it after a week because of the hesitation. Had to buy OEM
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Old Jul 25, 2010 | 08:48 PM
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Corrolla
not sure why MB likes OEM parts.

Andy
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Old Jul 25, 2010 | 08:55 PM
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Originally Posted by dynomite05
I hear ya but MB's are like that. I tried using an aftermarket MAF a while back, had to change it after a week because of the hesitation. Had to buy OEM
MAF? Sorry not sure what you mean. Alternator?
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Old Jul 25, 2010 | 08:59 PM
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Originally Posted by M-bENZ
not sure why MB likes OEM parts.

Andy
Yeah I know the MB dealers love OEM parts. They try to tell me all the time that aftermarket won't work and won't be any good. Up until now, I've always proven them wrong and had fine performance from aftermarket parts (plus I've kept $$$$ in my pocket). I get PO at the dealer when they tell me only OEM will do. In many cases, if OEM was so good I wouldn't be looking for a replacement.
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Old Jul 25, 2010 | 09:11 PM
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Mass Air Flow. You could get OEM parts a lot cheaper than the dealer from parts.com
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Old Jul 27, 2010 | 10:11 AM
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Engine hesitation seems to be going away (??). But now it's doing a weird thing - driver's side rear window opens just a crack on its own. I haven't caught when it does it, maybe when the car is started. It's gotta be related to the new alternator. But how???
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