TheOtherEric

Accelerating down the front straight at Putnam this weekend, got up to around 90mph when the dashboard lights up like a Christmas tree! We all know what that means: broken alternator belt. Of course, I somehow never got around to stopping by AutoZone (or the porsche dealer) to pick up a spare like everybody says you should. So as a PSA, here is what you need to know:

- Robin's site has a DIY on changing the belts. http://p-car.com/diy/vbelt/

- Make sure you carry an extra alternator belt, either from a porsche dealer or from any ol' auto parts store (I got one at Autozone, $3.99)

- Changing the alt. belt is actually painfully simple (~20 minute job):

1. You have to remove the a/c belt to get the alt belt on, so just loosen up the a/c compressor (13mm bolts) to get its belt off.
2. The alt belt pully is split; so just remove the big 24mm (15/16") nut to separate the two halves. That's where you need the triple-square tool (available at autozone, pep boys, etc., but probably NOT in your tool kit unless you're lucky).
3. Slip on the new belt and put the pully back together. Adjust the belt tension by adding/subtracting washers between the two halves. The washers are already there. I didn't use any fancy tensioner tool; doing it by feel is fine in a pinch.
4. Put the a/c belt back on and tighten down the a/c compressor. Done!

We all would be wise to update/check the tools and spare parts we carry with us. Here are some ideas by Jeff Chan:
http://www.cuberootconsulting.com/~j...ve.html#000051

jcoll1

Eric, I wish I would have known you needed a belt this past weekend. I had an extra one in my tool kit! I was running in D group. Sorry that I did not get a chance to meet you in person this past weekend. Hope you had a great time besides that alt. belt incident.

jimbone

Eric,
Sound advice. I just had the exam same thing happen yesterday pulling into the track for the end of a DE weekend. Luckily, a race group had an extra belt there and changed it for me, to the tune of 120 bucks. Worth it though, cuz they changed it a lot faster than I could have and I didn't miss much lap time. Thanks for the write up, after seeing it and printing out your post, I'm gonna go better prepared next time! Thanks.

TheOtherEric

Doh! I thought I asked every 993 owner there, but I guess I missed the ONE person who had a belt. Oh well, I only missed one session anyway.

Sorry I didn't get a chance to meet you Jason. You might have seen me out in D since I took a couple folks for rides. Were you in your 993?

tsky

I suggest everybody inspect their belts. I was surprised how bad a shape my alternator belt was in. I just changed them all recently.

It's not hard to do but be very careful with those alan bolts holding the pulley as they are easy to strip (read the DIY and archives to know what I'm talking about). Consider buying new bolts when you are picking up the belts.

Rick Lee

Eric, how long did your engine run after the belt broke?

TheOtherEric

I don't know how long you could run the engine on battery power alone. I suspect I could have driven into town to get the new belt, but I didn't try it. Obviously there was no problem driving around the track back to the pits.

Rick Lee

It's got nothing to do with battery power. Plenty of folks have completely cooked their heads by trying to limp home with no alt. belt. That fan is all that cools the heads. Your oil temps won't go high until it's way too late. I think you have under one minute to shut her down and not cook your heads. If you were pushing it hard on the track until you got to the pit, I'd take her in for a leakdown test.

TheOtherEric

I'm confused. How is running with no alternator belt any different from running WITH an alternator belt? AFAIK the only difference is that you're no longer charging the battery, so it will drain relatively quickly. Basically the same as driving with a dead alternator. The engine's fan will still turn and the oil will still pump. Now, if the FAN belt broke, that would be different.

At any rate, it was the first lap, and I just limped back to the pits. So there's nothing to worry about.

EDIT: Oh, you must think that my FAN belt broke. It didn't. I don't have the RS pully, so I still have 2 different belts.

Rick Lee

Oh, then your fan was still moving? No problem then. On a pre-89 911, your heads would have been done for.

TheOtherEric

Yup, the 993 has 3 belts at the rear of engine: fan, alt, and a/c. So my fan was still moving. We also have a warning light to tell us if the fan belt goes: it looks like a belt on 2 pulleys. Like you said, that light means "don't drive"!

Tom W

You can run for about 30 minutes on battery power - I've (accidentally) done the test after killing my alternator and not realizing it. I was into the second session on the track before it died.

I always carry spare belts. Don't forget to check with 964 owners when you need parts.