Mike Murphy

My V-belt is pretty loose and I think I need to tighten it. Trouble is, I don't think I have that special tool to loosen the huge nut off the alternator. Unless of course, that is part of the tool set that came with the car (which I have). So can I use an impact wrench to pull of the V-belt? Will it hurt the alternator any?

theiceman

THE pulley holding did in fact come with your factory tool kit so it shouldn't be a problem. I have a 78SC with the original alternator and the nut is very specialized with a very fine thread. I would not suggest an impact gun. you have to retighten it anyway. I would suggest buying or manufacturing the pulley tool if you don't have one.

Mike Murphy

Thanks, I'll check the tool kit. My mechanic found that belt to be loose when he was doing my valve adjustment about 1,500 miles ago. Now the belt is loose again. How often does this belt need to be tightened?

Pelican and VertexAuto make both a service-free and NOT service-free belt for this car. I assume one belt doesn't require tightening and the other one does?

theiceman

not sure and I can't really comment as my car only has about 8,000km on it since I put the belt on, the belt was fine and did not need tensioning until I tore the thing off..... another story...

But tightening the belt is not really a big deal if you have the tools, and how do you determine too loose without belt tension specs. If the alternaot light is not coming on and the engine cools I wouldn't worry about it . ( unless it is REALLY bad ) . I have seen the bigger problem being they are put on WAY too tight , some guys think that belt is holding the whole engine together, and guess what , they are the guys replacing alternator bearings , or whole alternators and fans.

ice ...

Droops83

Don't use an impact wrench to rempve the pulley nut. Do yourself a favor and buy the counterholding tool if it is missing from your toolkit. Any Porsche parts supplier or Ebay should have this. As a general rule of thumb belts should have about a 1/2" of deflection for every foot of belt length. The distance between the alt/fan pulley and the crank pulley on a 911 is less than that, so somewhere between 1/4-1/2" would be ideal. If you want to be really proper then get one of those cheap clicker type belt tension gauges at NAPA or somewhere like that and tighten the belt to factory specs, which i do not recall since I guess I do this so much i just do it by feel. Remember a new belt will stretch a bit after a few minutes of running, so set it a bit on the tight side at first, and check the tension again after a few minutes of running. Do not tighten the belt too tight, since you can indeed wear out your alt bearing like iceman said, but also the upper part of the main bearings in the front of the engine, which is really bad. I have no idea what the hell "service free" means, since you should always periodically check the tension and condition of your belt. Even if there are no cracks, turn the engine over by hand till you see the seam where the 2 ends of the belt were bonded togtether at the factory, make sure it is not starting to split there, that is where they break most often!

---

Chris Andropoulos
Schneider Autohaus
Santa Barbara, CA

Mike Murphy

I've got an inch or more of deflection. I mean this belt is really loose. I will inspect it to find out why it has suddently become so loose. It's not like the pulleys could have changed shape or moved at all. I actually bought a spare belt before I noticed it for a "just in case" repair. I just didn't want to be stranded somewhere without cooling and charging. I just think it's strange that the belt continues to become loose. Perhaps it's coming apart slowly!

theiceman

Well murph if you don't want to get stranded somewhere do 2 things.

Buy the tool if you don't have it ( spare belt won't help you if you can't change it )
Practice changing it before you break down.

I can tell you from very recent first hand experience that practicing changing the belt and being familiar with the shims will pay off, as I just had to change mine at night and it took me all of 20 minutes.

ron mcatee

You've heard the term, Not only no, but heck no. Use the spanner wrench that came in the tool kit to do the job properly.

glenncof

Tighten belt by removing the spacers (shims) between the two halves of the pulley. Get the right spanner tool, heck, just get porsche tool kit. The 24mm wrench is in the standard Porsche tool kit also.

When I replaced the belt. I put the old in the tool kit as spare.

theiceman

That floppy bit on the front of the tool kit is to hild a spare belt anyway.

rnln

May I ask why can't use impact gun to get that nut out?

theiceman

firstly good luck getting one in , secondly. if it doesn't get the nut off you could spin the fan and hurt yourself and lastly it is a really fine thread and you risk stripping it and ruining your alternator.

Droops83

Iceman is exactly right as to why you should not try and get the nut off w/ an impact wrench. But even if you do get it off ok w/ an impact, you still need the factory counterholding tool to get it back on, so it makes no sense.

---

Chris Andropoulos
Schneider Autohaus
Santa Barbara, CA

Mike Murphy

UPDATE: I found the tool kit and all the tools seem to be present, including both tools to get the pulley off. What I found are 5 shims, all on the outside. As I understand it, and correct me if I'm wrong, I know I should have 6 total, but since they are all on the outside, the last shim actually makes no difference in the tightness of the pulley. It appears that if all shim are on the outside, the pulley is closest to the fan, and thus, as tight as you're gonna get it. So it turns out that my belt is still pretty loose, although I might just let it be. I do have a spare belt that I keep in the trunk. If it gets worse (looser), I might replace it. I may also have to find a belt that is a little smaller or tighter is the new one is just as loose.

FYI - the belt deflects about 1 inch, but I get no squeal or unusual noises indicating slippage. The AC belt is tight as it should be according to spec., it appears.

ron mcatee

If you don't have a 9.5mm X 710mm belt or at least a 10mm X 710mm belt, your never going to get the belt tight. I'll bet you've got the wrong size on there.