Hi,
I have a town car 2010 with 194,000km on it.
My alternator died so I replaced it with a new ACDelco one.
Now my car is making high pitch noise in sometimes the rpm go slightly up and down while ideling.
This made me think I have an air leak, but I cannot find where it is. I tried everywhere and could not find it. Can it be a faulty alternator?
No codes, and the alternator is charging perfectly. I also replaced the serpentine belt, can that be the cause.
Here is the video with the noise:
Thank you!
How old is the belt? If your old alternator was weak it was not loading the belt very much. A new one generating more power is going to put more stress on the belt.
Other than that I would remove the fan belt and spin all pulleys by hand to see if you can feel roughness in any of the bearings, including the new alternator. Given the race to the bottom in quality these days it would not surprise me at all to see a new AC-Delco built alternator with bad bearings right out of the box.
I replaced the belt with the alternator. The belt is brand new and OEM.
The noise does goes away when I rev up the engine.
Does it not sound like an air leak?
I guess I have to take the belt off and see if it's one of the pulleys.
Which reminds me that I also replaced the tensioner together with the belt and alternator. But it is brand new an OEM too.
You can run the engine BRIEFLY with the belt removed and see if the noise remains.
I think it's the alternator. If you can't tell from spinning it by hand and still have the old alternator you could put it back on and see if the noise stops.
Use a 3ft piece of PVC pipe or hose as a stethoscope and determine where that noise is coming from.
(in the video it seems to be the alternator but make sure).
Scotty did a video on using a long screwdriver as a stethoscope but most guys don't have a 3ft long screwdriver. You can use a piece of garden hose or PVC pipe.
First, turn on your headlights + high beams, your A/C, and your blower motor to high.
(make the alternator work)
Then just hold one end to different components/areas of the engine (like your alternator), and the other end to your ear, and narrow down where the noise is coming from.
If it's the alternator that's whining, it may be that it's working too hard.
Maybe your last alternator didn't die. Maybe it was killed!!!
Here's a pretty good video on how to test for voltage drop between your battery Negative to engine ground circuit, and the positive circuit between your battery Positive and alternator.
It's good because the instructions are easy and he includes the acceptable voltage drop limits
https://www.youtube.com/watch?v=DVl7vcFzCCw
{blackemo}:laughtertotears:
.. with the wrench, in the study!
With an aftermarket part, it is likely the circuits will not function the same
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There is no more OEM alternators for this car. What does it mean that the circuits will not function the same? The alternator generates the same voltage
Bad things can happen to the electric compenents, and wiring with incorrect voltage, Most likely: Possibly accidentally either loosened or damaged a spark plug cable near the alternator. The new alternator is either undersized (overloaded by your accessories) or defective. (Not putting out the rated voltage and current at idle speeds.)