Front accessory squeal/vibration, alternator?

Topic: Front accessory squeal/vibration, alternator? (Read 1894 times) previous topic - next topic

Front accessory squeal/vibration, alternator?

April 11, 2017, 12:00:10 AM

So yesterday I took the Thunderbird out for a drive after it sat all winter. Everything was fine. After the car warmed up I did some wot runs. There was a weird squeal and vibration I could slightly feel in the floor from 4000-4200rpm. Above or below that range there was no noise/vibration. I went home and could duplicate the condition with the car in park. So to narrow the issue down I removed the accessory belt and started the engine. I revved the engine up to the same speed (4000-4200rpm) and the squeal/vibration was gone. That ruled out the damper, crank, and torque converter and isolated the issue to the front accessories. The water pump pulley, smog pump eliminator pulley, A/C compressor pulley, and power steering pump pulley spun straight and true by hand. The alternator pulley, however, wobbled slightly when spun by hand. I put the belt back on and the squeal/vibration was back. I listened to the alternator with a stethoscope and, when the engine was revved up, the alternator clearly made a noise I could hear through the stethoscope.

So based on the process of elimination I'm fairly certain the alternator is the culprit here. Has anyone has a bad alternator shaft/bearing resonate through the car at high RPM? The alternator has a lifetime warranty so it will cost me nothing to swap out.

Front accessory squeal/vibration, alternator?

Reply #1 – April 11, 2017, 04:54:32 AM

I've seen bent shafts.... Had one on the Lincoln.

Front accessory squeal/vibration, alternator?

Reply #2 – April 11, 2017, 07:51:09 AM

What Paul said...I had a bent shaft on my '92 F150's alt...

Front accessory squeal/vibration, alternator?

Reply #3 – April 12, 2017, 10:08:33 PM

I'll be swapping out the alternator as the 3G unit I bought has a lifetime warranty. So it's a free swap. I'm just surprised it died in only 2 years. The belt is not too tight or anything.

Front accessory squeal/vibration, alternator?

Reply #4 – April 19, 2017, 09:42:34 AM

After your alternator swap-out I highly recommend replacing the serpentine belt with a Goodyear Gatorback (Note: Continental took over production and renamed it the Elite Poly-V Belt with Quiet Channel Technology.) I was chasing a belt squeal for over a year before I discovered the high grip Gatorback. New belts were quiet for about two weeks before the squeal/chirp returned. Drove me crazy. The Gatorback has been on for the last six months with no chirp or squeal.

Front accessory squeal/vibration, alternator?

Reply #5 – April 20, 2017, 02:09:33 AM

It really shouldn't squeal no matter what unless somethings messed up. I run cheapie belts and have no squeal.

I was in love with my 3g upgrade. But after doing it, meh. Not really that much difference. I felt like it was a worthy upgrade on my cougar, but driving the tbird I don't miss it.

Front accessory squeal/vibration, alternator?

Reply #6 – April 26, 2017, 02:41:18 PM

Turns out the 29 year old belt tensioner is ping out. When the bearing squeals there is no vibration. When it doesn't squeal there is a vibration. I guess after 29 years and 135K miles it's time for a new one.