Luftd993

I’ve just put on a Contitech 13 x 1100 on the A/C and I’m very pleased with the size. It was the first time I’ve had to use the tension bolt and could get the tension just how I like it.
When the belt wears down there is adjustment available.
The image below was taken when the belt was at correct tension.

IXLR8

Thanks for doing so, David.

Does this mean you were able to slip that 1100 belt over the A/C compressor pulley with the compressor up against its left-hand most stop?

Luftd993

Alex. I do not think it would be possible to slip a belt on without pulling the 3 bolts and still get enough adjustment to tension it because of the angle of adjustment in relation to the crank pulley. I’m guessing you could slide the compressor along 5mm and it pulls the belt 2mm.

bruce7

The belts on my car have 23,000 miles on them and recently I am hearing
what sounds like a probable belt squeal in the morning for the first couple
of blocks, then it goes away. The belts look good so I don't want to replace
them yet, only 1-1/2 years old. I checked the tension using a Krikit gauge,
and the Alt/Fan are in spec, however, the A/C belt measures 25 Kg. This
would appear to be about 10 Kg over spec (should be 15-18 Kg?). What
are other people able to measure with this belt?

I would expect a loose belt to generate a squeal not a tight one. So I'm
confused. I haven't moved the A/C yet to adjust the tension, but it appears
to be fully against the stop. The belt is a Porsche belt, 999.192.363.50.

I see that the PET says it is 12.5 x 1085, but the belt is actually 13 wide?
It appears to ride high on the A/C pulley. Would this wider belt
change the tension spec to a higher number?

The belts were installed when I bought the car by a Porsche dealer, so I
would expect them to have tensioned it correctly. Just wondering if the
spec was changed. Wouldn't that be on a TSB somewhere if it did?

If the spec did not change, then might this high tension for the last 23k miles
have hurt the A/C magnetic clutch? The belt tension sensor was replaced
last summer, although I suppose it could be going out again, but so soon?

-bruce

EMBPilot

Bruce,
It sounds like your due for new belts. There should be no squeaking. I was getting a very minor squeak that lasted start up until about 2 minutes. Changing the belts resolved it. They had about 15,000 miles on them and were prob 5 years old.
Doing a proper belt job is very straight forward. Esp w the guys here on the forum.

bruce7

Hi,

Thanks, I've got all the parts ready to go so maybe I should just go ahead
and do it. Just bothered about that tension reading on the A/C belt.

-bruce

EMBPilot

If your reluctant, then just change the AC belt, or open the lid and try to determine if it's the AC belt that's making the squeak.

The Porsche belt for the AC is awful. It's too short and puts the compressor up against the stop. I believe Alex has very recently found the perfect AC belt. Hopefully he'll chime in here.

Falcondrivr

I run NAPA belts on all 3 pulleys. Current set is over 25K miles on them with no problems. They are .5mm wider than the Porsche belts, so you have to adjust the shims to compensate. Im not sure of the AC belt size, but the others are 780x10 and 760x10.

IXLR8

That it does. What was Porsche thinking?

Unfortunately, I haven't. That 13 x 1125 belt was a tad too long (looking at my math later, no wonder). It slips over the pulleys without having to unbolt the AC compressor, but there isn't enough adjustment on the mount to take up the slack.

David in post #16 above installed a 13 x 1100 belt, and although it does not allow the belt to be slipped over the pulley, it at least is longer so that the adjustment bolt can be used to tighten the belt properly. The only other belt I found was a 13 x 1118 and that may be too long as well.

bruce7

What tension do you measure for your A/C belt 13 x 1085?

-bruce

IXLR8

Bruce, when my AC compressor is back in position on its mount with the 13 x 1085 belt, it is right up against the mount's forward stop. I don't use the adjuster bolt and locknut because I feel the belt is tight enough as it is. I never performed a tension measurement as I have on the fan and alternator belts.

I would use the 13 x 1100 belt that David tried where the tension bolt can then come into play.

pp000830

See attached

bruce7

Thanks, but that only covers the Alt/Fan pulleys. The big question is
what about the A/C belt tension.

What I'm getting from the feedback here so far is that the belt is so
tight when installed that no additional tension is added via the adjustment
screw and further that no one even bothers to measure it. If they
did they would find that it is over spec, and with no way to adjust it, the
spec becomes a moot point.

skl2

just did all three of my belts yesterday..as well as the tension senor. It was easier than changing the oil! Everything seems within spec right now...Im going to drive it for a while and remeasure the tension.

IXLR8

"So tight" as in as tight as I'd want it in my case. Without taking a measurment, I can tell if the belt tightness is way past my comfort limit.

The belt is supplied by Porsche and was used. Note that they still list a 12.5 x 1085 belt (which would provide some slack) on the on-line parts listing yet when you order the part number associated with that belt, you get a 13 x 1085. Go figure!

I'll be installing the 13 x 1100 belt as per David's recommendation.