replacing the alternator

[cowboyili]

i'm trying to replace my alternator on my 98 pontiac GTP grand prix. the supercharger belt is kind of blocking the way to the tensioner on the main serpentine belt, but the tensioner is somewhat accessible. the problem is, i cant find out how to loosen the tension on this. theres no form of screw or nut in the center of the tensioner. can anyone help or direct me on how to remove the alternator?

[BNaylor]

Thats interesting. The tensioner is supposed to have a bolt.

MAKE SURE YOU HAVE THE BATTERY DISCONNECTED BEFORE PROCEEDING!!!

To remove alternator first remove the accessory belt.

Use a 15 MM wrench/socket and rotate the tensionser (just below the alternator pulley) counter-clockwise, then slip the serpentine belt off.

Then disconnect the electrical plugs to the alternator.

Remove all the bolts to the alternator. There is one that hides back behind the alternator, very close to the firewall. Remove this and slide the alternator out.

[cowboyili]

well i see a pulley that's connected to the tensioner, but that pulley is part of the supercharger pulley system. in the center of the tensioner is just a circle. i even checked out a new tensioner and there is no bolt at all in the center of the tensioner.

[Cbioc32903]

Most likely you should not be looking for a bolt in the middle of the tensioner......you should be looking for a bolt on the tensioner pulley coming off of the actual tensioner. usually that is how you release the slack by putting the wrench to the bolt on the pulley and turning it.

[BNaylor]

For the main serpentine drive belt system you are supposed to wrench the tensioner which has a 3" pulley and a 15mm bolt holdling it on located below the alternator.

See pic below which shows the serpentine and supercharger belt system. Red arrow points to it. #3.

[cowboyili]

Okay, that helps a tremendous amount. First off, let me say an unconditional thanks for your help because this information is not available anywhere else. So, that pulley does not swivel like the supercharger belt tensioner does. With the supercharger belt, you wrench it and it will pivet in which obviously loosens the belt. I will loosen the bolt on the tensioner pulley and finish it tonight. Out of curiosity, how does that work if the pulley doesn't swivel? When you loosen it, how does it cut slack in the belt?

[BNaylor]

Originally Posted by cowboyili

Okay, that helps a tremendous amount. First off, let me say an unconditional thanks for your help because this information is not available anywhere else. So, that pulley does not swivel like the supercharger belt tensioner does. With the supercharger belt, you wrench it and it will pivet in which obviously loosens the belt. I will loosen the bolt on the tensioner pulley and finish it tonight. Out of curiosity, how does that work if the pulley doesn't swivel? When you loosen it, how does it cut slack in the belt?

Actually the main tensioner does swivel/pivot similar to the supercharger tensioner. Counterclockwise for the main serpentine tensioner and clockwise for the supercharger tensioner. The bolts in each pulley are threaded differently.

You do not need to remove the main tensioner pulley but just put a 15mm socket or wrench on it. Depending on the condition of the tensioner it may need some extra force. If you are having problems moving the main tensioner and cannot remove the drive belt then it may have a problem. Tensioners on the '97 models and maybe into '98 were flaky.

[cowboyili]

Interesting. Again, I appreciate your help and I'm sure I'll have this alternator in tonight thanks to you. Getting the belt off was the only problem for me. After that it's two bolts, an electrical connection, and what looks to be a ground wire connected to a petruding bolt. Thanks man!

[wrightz28]

Does the tensioner have a little square at the end that a 3/8" ratchet conveniently fits?

Quite a bit of aftermarket tensioners lift that way.

[BNaylor]

What brand are those? I worked with aftermarket brands like Goodyear tensioners and they match the stock design. Even the ones sold by AZ match stock.

Of course, the GM 3.1/3.4 tensioners have the 3/8" square.

[wrightz28]

I've seen em from AZ and Napa for 3.4 and 3.8, thus assumed that since no bolt is visual, that it might also apply to a 3.1, I don't really think there would be much of a difference in them anyway aside from sprung pressure

[BNaylor]

Originally Posted by wrightz28

I've seen em from AZ and Napa for 3.4 and 3.8, thus assumed that since no bolt is visual, that it might also apply to a 3.1, I don't really think there would be much of a difference in them anyway aside from sprung pressure

Big difference. The tensioner on a SII 3800 has a heat exchanger. Coolant flows through it. We have a plastic 90 degree elbow connected to the lower intake manifold from the tensioner that will leak or disintegrate from tensioner vibration.

[wrightz28]

Oh, never mind then, I must have got my threads mixed up,