I put a new alternator in my 08 F150 22 months ago as the original had bad bearings. So anyway, noticed recently at higher rpm running down the highway it sounded like it had a turbo on it. Found all the idlers and tensioner were bad, so replaced those and a new belt. Took it for a drive and still have the noise. Pulled the belt off again and checked everything else. The water pump and ps pump turn nice and quiet and the ps pump is full of fluid. The alternator squeaks when turned over at low rpm. Could this be doing it? It is no where near as bad sounding as the old one was and I didn't notice it screaming at higher rpm. The new alternator does have a lifetime warrenty on it, but they will test it before giving me a new on. What does everybody think? Am I on the right track or am I missing something? Thanks

 

Sounds reasonable, worth it to test before buying anything else.

 

Just tell them it's making noise..bring them outside and let them listen to it.

 

Is it a motorcraft alternator or a no name aftermarket?

 

I assume its aftermarket due to the fact he mentioned it has a lifetime warranty.

 

Oops. I missed that. I'd go oem. I tried an aftermarket one once and had nothing but issues.

 

A new OEM Ford unit if you can find it is well worth it. The aftermarket units you will be replacing once every couple of years as you have discovered.

 

It was rebuilt in house by a local starter/alternator shop.

 

Your Ford OEM alternator was rebuilt? If so, he/she needs to replace the bearing(s) again, as they sound like the culprit.

 

Agree with Bucko, the bearings are likely going again.

Many (not all) of the bearings we're getting now are just junk, it's one of the major reasons that the only way to go with a new alternator is Motorcraft OEM.