jthwan22

My SC belt been slipping ever since I got the car. So I order new belt from 928 motorsports. It is NAPA#080415 size 1-3/32" X 42-1/8". It is so tight I can't get it over the SC pulley. Even with the tensioner at full loose. The SC belt that came with the car is longer at 44"

Is the NAPA belt correct? If yes, how do I get it on to the pulley?

aggravation

I just put mine on and had it hanging from the crank pulley, tensioner completely disconnected bolt hanging free, brought belt up and into position between idler and tensioner and it slipped right over the blower pulley.
No struggle involved, then put tensioner bolt through the hole and installed spring and washer and nut...then tighten.
Sorry I don't know the part number to be able to tell you if the one you have is the same.

hacker-pschorr

Ok, easy stuff first, make sure (100% sure) it's fully seated on the pullies. This might seam obvious but it happens all the time.

Putting on a new belt can be tight, takes only a few minutes at idle to "break it in".

You might try pulling the tensioner rod out of it's hole, this should give you enough give to slip it over the lip of the pulley.

What size pulley is on the SC?

jthwan22

The SC pulley is about 3-3/4" The tension rod is completely out. I even remove the oil dip stick so the tensioner pulley can swing out more. Do I have the right belt for the pulley? Can I get a belt that is 43" long?

hacker-pschorr

The Murf928 belt for that setup is the Bando 1075mm. I'm not sure where the NAPA one came from.

To try and use the belt you have, put the belt completly around the supercharger pulley, then try and get the edge of the belt started around the crank pulley. Then use a breaker bar to rotate the engine (clockwise only) to walk the belt on.

If you try and walk the belt onto the supercharger pulley, the lip of the pulley could cut into the belt. The crank pulley doesn't have a lip.

jthwan22

Thanks for the info on the belt. Is there a stock # for that belt? Who would sell it? I will try to walk it on like you said. It may still be too tight. Removing the AC, PS, Alt belts are PIA. I just finish WP and TB and hate to repeate work.

hacker-pschorr

I would call your local auto parts stores, if they carry Bando belts, 1075 is the number on the packaging.

Does your tensioner rod have the little metal spring?

jthwan22

Yes, a yellow spring.

AO

I'm preety sure this was this was the car I saw at SITM and the spring looked right.

The symtoms were that the car wouldn't make boost. Maybe 1psi at most. I believe he chacked for leaks but didn't find any.

The belt didn't look too bad to me, but then I could only see the back side of the belt and I was drinking heavily by then.

FYI... boost gauges are not always accurate. Mine is a POS! Made me chase a ghost for a long time! I thought I was loosing boost... I wasn't.

jthwan22

Yes, I was at SITM this year. The belt I took off looks ok. I can't read the writing that was on it anymore. It was not making boost. I didn't check for boost leak yet. I am still building a tester for it. It has been down since SITM due to a coolant leak out of the tensioner bolt that go into the WP. I don't think PO put any RTV on the thread.

Jim R.

If you can't find a bando belt locally, a Gates micro-v belt fits. Part # K080427.

Make sure the pulleys are clean and degreased, but I would bet the low/no boost issue resides under the intake manifold, not the belt.

Jim

AO

If you haven't checked for intake leaks, then it's too early to assume it's the belt.

Make one of these and you will see the light...

https://rennlist.com/forums/928-forum/445400-diy-vacuum-intake-leak-tester-for-s3.html

Imo000

To only make 1lb of boost, the belt would have to slip really bad, to the point that it would start to smoke and squeel. Seprentine belts are sandard and they come in standard sizes. Are you sure the new one is the same length as the old one? I'm going from meomeory here, but I think, they come in 1cm (1/2") increments and it's easy to get the wrong size if you don't know the exact length of the old one.

jthwan22

Good trick using the crank pulley to get the new NAPA belt on. The belt is so tight the tension rod is not passing thru the hole. The new belt is 42-1/8" and the old belt is about 44" long. I need to track down the Bando belt 1075, or Gates micro-v belt fits. Part # K080427. I hope they are about 43" long. Can I just run it with out the tensioner pulley? The belt is not going anywhere.

hacker-pschorr

I would not run without the tensioner pulley hooked up. Try connecting it without the spring, run the car for a mile or two to break in the belt then install with the spring.

I wouldn't run it hard until everything is hooked up as intended (with the spring / washer). Just running the car at idle will break in the belt.