Squeaky alternator on Ford

After just getting the thing out of the shop today (new brakes front, new brakes & seals rear, replaced tie-rod ends), out 98 Windstar has a new problem.

This time, the alternator is squeaking loudly. With the hood open,
I narrowed it to the general region, then used a burst of WD40 on the alternator’s pully hub to localize the problem to the alternator.

So, can I grease the alternator bearings or do I have to replace the thing outright? (This one has about 90k miles on it).

The replacement process seems pretty straight forward. I can see the tension wheel in the back with a single central nut to loosen to get the uni-belt off. The alternator seems to be held on with only three bolts.

Is there a trick or special tool to move the tension wheel back into
place? Is my engine metric or SAE?

Any advice appreciated.

Is it a bearing noise or a belt slipping?

It may just need a new belt. It may really need a new belt if you got WD-40 on the old one. :slight_smile:

The nut on the tensioner is NOT there to take the pulley off. You should be able to apply force to it and cause the tensioner to stop pressing on the belt without the nut coming loose. Once the belt is loose it’ll practically fall off on its own. The trick then is to snake a new belt back onto the pulleys.

Replace the $5 belt first. If it still sqeaks take your alternator out and clean any gunk off of the pulley and hub. Be careful not to get solvents or cleaners into the alternator as they could eat seals and permantly lubricated pieces.

I’d suggest gettign a Chiltons or Haynes manual for your vehicle. Chiltons is better, but for the basics Haynes will get you by.

The belt tensioner is spring loaded. As NevarMore indicated, you move it against the spring tension to relax the belt. Usually this is done with a wrench on the tensioner pulley bolt; some designs have a square hole in the tensioner arm to use a 3/8" or 1/2" square drive tool. I would expect the pulley bolt and alternator bolts to be metric, but it’s not out of the question that they’re SAE.

With the belt relaxed, it can be easily slipped off a pulley, after which you can release the tensioner. Be aware that the tensioner will move beyond where it was to its own stop point, since it won’t have the belt to stop it. To replace the belt, thread it onto all but one pulley, then pull the tensioner as far as you can to make room to slip the belt onto the last pulley.

Usually there’s a belt routing diagram on a sticker somewhere under the hood. If you don’t see one, make your own diagram before removing the belt.

As Berkut intimated, a squeaking noise could have caused by the belt itself or by the alternator. The WD-40 could have quieted either one. If the noise returns, you can sort it out. Try a hit of WD-40 on the ribs of the belt somewhere away from the alternator. If the noise stops, it was the belt. If the noise remains, try to hit the alternator just behind the pulley, not getting any on the belt. If the noise then stops, it was the alternator.

There’s no practical way to service alternator bearings. They can be replaced, but without some experience and correct tools it could be a major pain (or worse). I would advise getting a quality rebuilt alternator.

Your description indicates a serpentine belt (snakes in and out among several pulleys) which means it’s multi-ribbed and long, which means it’s going to cost noticeably more than 5 bucks.

Yeah, a new belt is $30, I’m afraid - a rebuilt alternator from NAPA is $140. I’ll replace the belt on general principles if I take it off since this is the original belt (seems in good condition, though).

I’m almost sure it’s the alternator bearings. The WD-40 was pretty targeted at the inside of the alternator pulley. I just tried it again before this reply and while the spacing is too tight to get the nozzle behind the pully, a small burst inside the pulley still fixes the sound. The pulley has a large flange so I’m pretty sure none got on the belt.

The squeak isn’t steady. It starts out quiet on the cold engine, then starts to chirp at the speed of the rotation. I’m 99.99% sure it’s not the belt slipping.

So the tension pulley is spring loaded, huh?. Hmmm. Sounds like I need a loooong wrench (or - more likely, a longer rachet handle). There’s three lines raised on the casting, one on the arm and two on the engine mount. It seems obvious that the arm’s line is intended to be between the engine mount’s - perhaps to show cable stretch if it’s a spring-loaded bugger.

I can’t see a square socket but the viewing angle stinks. All I see is a central hex nut. I guess I’ll get the Chilton’s manual from the local library for this engine.


Yeah, if it’s the original belt it would be very wise to replace it.

You can get a special tool for this, but essentially it’s a long wrench with little or no offset. If there’s room to use a ratchet and socket, you can make a ratchet handle extender with a deep socket and a long extension.

Yes, the one mark should be between the other two for proper belt tension. A badly stretched belt can bring the marks out of alignment.

The great majority of them do not use the square hole. Put a wrench on the pulley center nut and push or pull to see if the tensioner moves against the spring – if so, that’s the way to do it. If the nut starts to unscrew, try the other direction (tightening the nut). Sometimes the direction to go is marked, sometimes it’s obvious, sometimes you just have to use trial and error.

You’re welcome. Hope it goes well.

No, it’s “Squeaky Fired at Ford.” Get your headlines right!

I wouldn’t be so sure. Those should be sealed ball bearings and the WD40 should not have worked anywhere into the rolling elements of the bearing… the seal should have easily stopped that.

The bearing would have to be failing so badly to take the seal out for the WD to do much of anything. Possibly there is a bushing or something else in there.

Who knows though.

I agree with those that say a belt has to be properly tensioned & of proper quality or you can get alternator bearing noise. One time we needed to try new 3 belts until we got the right brand that didn’t make any noise. All alternator belts are not created equally.