alternator questions

[GetMeMyStogie]

Hi there,

Last week I removed the belt on my stock MM to replace a squeeky idler pulley, only to discover that there is nothing wrong with either pulley. The squeeking is coming from the alternator, which I found when I spun the pulley by hand.
So, I've tried reading up on old forum posts about alternators, but I'm fuzzy on a few details:

1. What is the 'clutch pulley' people refer to? The pulley on my alternator seems fixed, like I've seen on most alternators. I'll take a guess that it's an electrically activated clutch, like for the AC compressor - if that's the case, should there be a separate electrical connector for it? Btw, I'm not the original owner, the car has high mileage.
2. The bearings are on their way out, but the rest of the alternator seems fine. Has anyone replaced just the bearings, at home?
3. The field coil is regulated by the ECU - does that make the MM alternator different from alternators used in Mustangs, CVs or MGMs? Is a replacement specific to the MM?
4. I'm also considering getting a tune (my MM is stock, though I'll be installing a free-flowing air filter kit soon). When a tune claims to turn off the alternator at WOT, does it do so by disabling the alternator clutch, or by turning off the current to the field coil via the ECU?


Thanks for any help :)

[FordNut]

Hi there,

Last week I removed the belt on my stock MM to replace a squeeky idler pulley, only to discover that there is nothing wrong with either pulley. The squeeking is coming from the alternator, which I found when I spun the pulley by hand.
So, I've tried reading up on old forum posts about alternators, but I'm fuzzy on a few details:

1. What is the 'clutch pulley' people refer to? The pulley on my alternator seems fixed, like I've seen on most alternators. I'll take a guess that it's an electrically activated clutch, like for the AC compressor - if that's the case, should there be a separate electrical connector for it? Btw, I'm not the original owner, the car has high mileage.
2. The bearings are on their way out, but the rest of the alternator seems fine. Has anyone replaced just the bearings, at home?
3. The field coil is regulated by the ECU - does that make the MM alternator different from alternators used in Mustangs, CVs or MGMs? Is a replacement specific to the MM?
4. I'm also considering getting a tune (my MM is stock, though I'll be installing a free-flowing air filter kit soon). When a tune claims to turn off the alternator at WOT, does it do so by disabling the alternator clutch, or by turning off the current to the field coil via the ECU?


Thanks for any help :)

1. It is a one-way clutch, mechanical.
2. Try wd-40? Probably best to just replace the alternator.
3. Marauder specific. The regulator is like a CV but the alternator case is like a Cobra.
4. Turns off the field coils.

[GetMeMyStogie]

1. It is a one-way clutch, mechanical.
2. Try wd-40? Probably best to just replace the alternator.
3. Marauder specific. The regulator is like a CV but the alternator case is like a Cobra.
4. Turns off the field coils.

Thanks man!

A one-way mechanical clutch, huh? I suppose that means when the engine accelerates, the alternator spins faster (like normal), but when the engine rpm drops abruptly (like during a firm shift), it allows the rotor/coil (driven by the pulley) to keep spinning at a high rpm while the belt and pulley slow down to the lower engine rpms. I noticed when spinning it by hand that the rotor is pretty heavy, and at high rpms a firm downshift would probably put quite a strain on the belt. So the clutch pulley helps to ensure longer life for the accessories belt.

[Blk Mamba]

I believe that our Alt. cuts out at wide open throttle.

[MrBluGruv]

Just fixed this problem myself, honestly I'd say replace the alternator if the price is right, it's just easier. I ended up paying $211 for a new Motorcraft OE alternator, so after that and replacing the tension arm and labor I spent maybe $350? Well worth it in my book, and this may be my imagination but the engine response feels ever so slightly smoother.

[gohogs]

You understand the issue pretty well. If you've ever driver a P-71 without the overdrive clutch, you get a hellofa squeal during WOT when the engine upshifts due to the mismatch in accessory speed to engine speed. Guess Mercury thought that would be unacceptable in a $35K vehicle. I think they were right!

[GetMeMyStogie]

You understand the issue pretty well. If you've ever driver a P-71 without the overdrive clutch, you get a hellofa squeal during WOT when the engine upshifts due to the mismatch in accessory speed to engine speed. Guess Mercury thought that would be unacceptable in a $35K vehicle. I think they were right!

Yes, I have noticed this recently. I thought it was my transmission, but now I'm thinking it's my fixed alternator pulley sliding on what is probably the original belt. Also, I hope it's this because it's much less $$ than a transmission ;)

[warren]

The clutch pulley helps to ensure longer life for the Alt. and frees up some HP--- it's important to have that pulley.
When I changed out mine I ordered the 200 amp.alt. kit from Reinhart Auto. that Came with the special pulley. It was very easy to install and had great instructions.

Warren

[GetMeMyStogie]

I had a closer look at my alt. Indeed it does have the clutch pulley, but it appears to have seized. I stuck a big screwdriver into the holes in the back of the alternator (wary of potentially shorting out any battery connections) and pushed on the internal fan blades. Pushing in either direction, I couldn't get it to spin - it just twisted on the pulley. I expected one direction to twist on the pulley, and the other direction to spin fairly easily.
I guess I have two reasons to get a new alternator.