Edgy01

Keep in mind that you will usually have to remove the a/c belt to get the alternator/fan belt on and off,--so remember that you will need a few more tools to deal with that belt. (I seem to recall that it will take a 13mm or so to loosen up the a/c compressor and then search for the adjustment/tension bolt that drives the compressor away from the fan center toward the right fender. You will doubtlessly find this belt's adjustment process to be a far longer job than the simple fan belt.

theiceman

Spider my thoughts exactly. he must have a narrow belt in there... especially since both are loose... BTW you fan housing isn't hitting the pulley is it :-) ..sorry mixed up with another thread, but make sure your housing is tight. I have used both a oem belt and a contitech belt and both are fine. if it is the wrong belt when your mech noticed it was loose he never really got it tight enough, also check your pulley half and make sure nothing is worn or chewing the belt, although you would know by the black rubber everywhere.

If I were you I would go buy aniother belt since you have come this far, and it you do find you have the wrong belt, buy two ...

ice

autobonrun

Not just for adjusting the belt at home but to do a full replacement on the road. Since you can't replace the alternator belt without removing the A/C belt first, I carry a knife in my onboard tool set, in addition to an extra belt and the necessary tools. I figure in a pinch I'll just cut the A/C belt off, do without A/C until I get home and save myself additional work along the side of the road.

Just another option.

Mike Murphy

Autobonrun, that's exactly what I plan to do - cut the AC belt if I have to install the fan/alt belt. I ordered the new belt from VertexAuto, so it should be the right size. As for the tools, I checked my set and it appears all the original tools are there. What I don't have is the air compressor for the spare tire, but everything else.

By the way, my AC doesn't work anyway, but I plan on getting it fixed next spring...

Mike Murphy

Well, I've finally thrown that loose belt. I was on the highway racing an M3 and Z28, going through the gears, redlining, etc. After a few minutes, I smelled something burning and immediately pulled over. I noticed that the oil temp gauge was just above the 1st mark. Since my car apparently never gets above the first mark in the fall/winter, I was concerned. The alternator light did not come on, so I thought it was something else. I popped the deck lid and saw that the belt had come off the alternator pulley, but it was still intact to some degree. The burning smell was simply the engine pulley rubbing against the belt...

It took me about 10 minutes to cut the AC belt (AC doesn't work anyway), remove the Alternator belt and reinstall a new belt I was storing in the trunk. The new one is tight. I'll see if the new belt stays tight. I don't have any more shims to remove, so I hope it does.

Needless to say, the old belt was ripped quite nicely

theiceman

Iwas reading up on thata little while ago and forgot to repost, with the old fan blade there should be about 15mm of delection of the belt in the middle. With the 11 blade fan you should tighten to 5mm of deflection.

Mike Murphy

OK, guys, it appears as though my new replacement belt is starting to loosen up on me. To reiterate previous posts, the previous belt was tightened by the mechanic and then 2 months later, it because so loose, I threw it off the pulley during some "spirited" driving. I had a spare on me that I ordered from Pelicanand replaced it. It remained tight for about 2 months, and now it is again starting to loosen up on me. Just yesterday, it started squealing when I had all the lights on, the fresh air blower on, and the heater on full blast.

What is causing these belts to loosen up on me prematurely? I am using the following belt from Pelican:

999-192-176-50-M21
Alternator or Air Pump Belt, 10 x 710 (Service-Free belt), 911 (1974-75), 911 (1980-89), 911 Turbo (1976-79), 911 Turbo (1986-89) Brand: Contitech

Furthermore, I should comment that I am missing 1 washer (I have 5 of 6) on the V-belt, but I had to place all 5 washers in front of the newly installed belt, which means that in this configuration, the belt was a tight as possible. When it was newly installed, the belt was tight in this configuration.

Do all belts need to be re-tightened after "break-in?" Should I go to a shorter belt since I am already as tight as possible with the 10 x 710?

theiceman

Something is wrong there for sure. On my 78 there is no way I can run with no washers as it would be WAY too tight. What is interesting is that I am running a 10 by 725 belt , which is longer than yours. My belts have never loosene although it is not a daily driver. is there nay sign of wear on the belt ? could the pulleys be damaging it ?

glenncof

I agree, something wrong here. I assume you are not over-tightening to the point of destroying the inner cords of the belt. This would lead to very early failure. Maybe your not tighten enough since you have removed all washers, as i understand, and the belt will strech some.

Maybe the wrong pulley halfs got on there somehow.

The alternator sits 'tightly' on top of the engine so I could see it requiring more washers if not seated properly (it's tricky, I know). Perhaps the alternator bearing is worn severely, check it for play.

glenncof

Pelican Prats has this listed for non-turbo 1978:
999-192-097-50-M21
Alternator Belt, 911 (1976-79), 10x725
Brand: Contitech

Which is LONGER !

Better check the pully halfs.

Pelican has:
PEL-RS-PUL2 Rothsport Outer Pulley Half (82mm), 911 (1976-89) for cars without second (air pump) drive belt.

Does your have (or should have) air pump ?

I'm suspecting there has been a modifcation.

Peter Zimmermann

The correct belt is 9.5x710 for the Carrera (9.5x725 on ice's car), and I wouldn't use anything other than a dealer supplied belt made by Goodyear. As Chris said, when it's installed new set it up just slightly tight and it will stretch to perfect before long. I set the 710 belt (after initial stretch) so I can just rotate the belt 90 degrees (using my fingers) at the halfway point between the two pulleys. Sorry, I don't do it by deflection...
Pete

glenncof

http://forums.pelicanparts.com/showt...hreadid=320850

You can verify the p/n and length by pulling down a complete book from Porsche. See above. Note it's large so I might not try using dial-up modem.

There was a half pulley change after 1979 (and corresponding belt length from 725 to 710) on SC's. There was also a change on the fan housing at that time. See page 51 of 481. Also I see changes on the impeller (fan blades, and is other half of pulley) and that time. And tensioning cap, though later '81. There may be other changes.

As ice said...something not right.

Mike Murphy

As Peter said, the correct belt is 9.5x710 and I'm using the 10x710. This explains the issue I'm having. I guess I misread and bought the wrong belt. I'll change it out to the correct one and report back after a while...

KC911

I don't think you bought the wrong belt...Pelican sent you the wrong one. Pelican sent me the Contitech belt (10X710) a while back. I was having another issue, so I swapped back to the Goodyear (9.5X710) that I had on the car since it was still in great shape. I seem to have read that Pelican now carries both, so I would contact them for the 'correct' one. Unless I missed it, no one has commented on the fact that you only have 5 shims....that is NOT good. You need to have six shims (whether inside or out) in order to prevent premature wear...don't neglect that, or you will pay later imo.

Keith
'88 CE coupe