Alternator bearing chirp

[rslifkin]

I'm thinking it's time to change out the bearings in my alternator. It's developed a bit of a chirp when cold (and occasionally when warm, although very quiet). The sound is definitely coming out of the rear bearing in the alt. However, if I pull the belt and turn the alt by hand, it still turns freely and smoothly, with no catching or anything.

I've put about 1500 miles on it since it first became noticeable, and it doesn't seem to be getting worse. Is there an easy way to add some grease to that bearing (not sure if it's a sleeve type or a ball bearing), or should I just plan to pull the alt and do the bearings when I have time?

 

[EricF]

you should be able to find the bearings, either timken or national should make them.
they are sealed bearings, so if you want to try and add grease you might try the needle nozzle, but you're going to create problems later.
replacing the bearings should be like $9 each..
However, while you're in there.. you might want to think about replacing the brushes while you're at it. Those are available, but getting harder to find nowadays.
In the end.. unless you have lots of time on your hands.. I'd just go out and get a reman alternator and drop it in.

 

[rslifkin]

I did the brushes and rectifier a couple months ago when the rectifier blew and shorted on me, so those are good to go.

The reason for rebuilding rather than replacing is capacity. The 5.9 Grand Cherokees came with a 150A alternator, which is no longer available. I could only get the 136A as a replacement. The only difference is in the stator, so I can use the 136A parts to rebuild the 150.

 

[mechtech2]

Stators don't wear out. Only if massive problems caused them to overheat or short out.
There should be little seals/end caps on the bearings. A pick can pry them out - they come out easily. They snap back in. Clean the old dry grease off, and try to find a special alt bearing grease. They actually DO use a special grease for best and longest life.
I admit to using moly chassis grease.
It needs not be said that new ones are available.

 

[rslifkin]

Ok. Sounds like it won't be too hard. When we've got decent weather over a weekend for me to pull the alt, I'll tackle it.

And the fact that the stator won't wear out and is fine is exactly why I'm rebuilding my 150A alt, rather than just putting in a 136A. All the parts are available except the stator, which I don't need to touch.

 

[oilboy123]

I used to do the older Delco ones years ago. I just bought one for my Ford. $155 out the door Ouch!

Well it's lifetime warranty.......Just hope it will last still, because I don't want to replace it every 2 years.

 

[mechtech2]

Another thought...
You can damage a bearing when when pressing the shaft out of it.
They can stick really well sometimes.
Or maybe the retainer plate will be bent. That is easily fixable with a hammer.