Alternator "groan"
I have a 1999 Mercury Mountaineer. V-8 AWD. It starts, and runs fine. However, it has developed a "groaning" sound, that I have tracked to the alternator, using an automotive "stethoscope".
I replaced the alternator, and the "groan" is still there, coming from the alternator. Could an idler pulley transmit this kind of sound to the alternator?
I'm out $150 for the alternator, cause I was positive that was the source of the noise. Now, I'm just baffled.
probably. take off the belt and check all the pulleys. should be able to feel a bad bearing.
a new alt with a bearing nose??maybe...idler pully maybe/// A BAD BATTERY WILL OVER WORK THE ALT ALSO...IS THE BELT GOOD/CLEAN/FRESH/GROVES/ DRIED OUT....
I checked battery with multi tester. Just shy of 12V with engine off. About 13.9 with engine running at idle. I should have known right then, that the alt was still good, but I thought it was the alt bearing. That's why I replaced it. Noise is identical, no change.
Usually a 'groan' or a 'growling' sound is the power steering pump, either low on fluid or on it's way out. Maybe you should try the stethoscope again, after checking fluid. it may not even be noticeable when turning, hard to turn I mean
The power steering pump was my first guess, but like I said, the stethoscope led me to the alternator. That's where the groan is coming from, just not sure what might be transmitting it there. Guess I'll have to go back out and pull the belt again, to check all of the pulleys.
Battery, engine off click for full screen
Temp is about 25F here.
Hmm, now I don't know what to make of that. If it starts ok, that 30% loss will be a 10% charge, and I just have a hard time with those figures. As long as it cranks over well. Unless I have it backwards, that same, we will call it 11.9V read ("Just shy of 12V") would be 12.3V above freezing and a 70% charge.
When I took my readings, I had just started the vehicle, and moved it into the garage. The chart says it should sit for 2 hours, to apply those numbers.
Pull the belt off and start it (don't run it more than a minute or so). Is the noise gone? If the noise is gone the problem is with something that the belt drives, such as tensioner, idler, alternator or a/c compressor bearing.
Went up to my local parts place, had them give a listen to my Mountaineer, and they agreed the " groan" was coming from the alternator. Their opinion was, that the belt tensioner was applying excessive tension on the belt. It seems that a belt tensioner would get weaker over time, not stronger. Does their advice sound logical?? BTW. Thanks, to all of you that have responded to my problem.
Personally, makes no sense to me. A spring loaded tensioner will not tighten up over time. I suppose the center bolt, not the one you use to relieve tension, but the bolt that hold it on, could get moved.
FYI.....My problem has been resolved. It was the belt tensioner idler pulley. It was transmitting the vibration to the alternator. My stethoscope was picking up the noise there. Swapped out the pulley, and it purrs like a kitten. Thanks everyone for the tips.
