Constantly slack fanbelt

[chris86uk]

Hi everyone,

I posted about a month ago about my fanbelt. The problem is, I replace the belt and the play is about correct, 0.5(ish) of an inch, but I have 0 shims between the pulley halves. After a couple of hundred miles, it's extremely loose again. I even paint marked the generator pulley nut to ensure it isn't backing off at all. The belts I'm using are 10mm x900mm.

I've taken some pics and a video to demonstrate this time. I've seen it said that the crank/generator pulleys being out of alignment will wear the edges of the belt (stands to reason). Note the black dust everywhere, which seems to agree with this theory. Also note, using my spirit level, how far out of alignment the pulleys seem to be.

I don't know how I could correctly align the generator pulley with the crank however. It's seated on the pedestal and bolted to the fan housing.

Any advice would be much appreciated.

Chris

VIDEO

https://streamable.com/aqvuoz


IMAGES

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[Mberglo]

Maybe you need a slightly smaller belt. Then you can put some shims between pulleys and be able to start out a little tighter.

[bsairhead]

Your belt should not ride that low. Ever. You need a shorter and or a wider belt. Your pulley could be subject also.

[bsairhead]

The picture of the torpedo level tells me you got butt sag, or your bus was parked on an incline or your mustache mounts are bad or missing. Alignment is not as critical as some would have you believe, it does change with shims. You should be able to eyeball that. Your belt riding that low in the pulley with no shims makes me think your pulley is the problem.

[richparker]

Looks like there is black dust all over the hoses, you’re probably shredding the belt. I’m no pro and I’ve never run a generator, but it sure does look like yours is clocked the wrong way. Looks like your connections are at 11 o’clock and I think they should be at 1 o’clock. Maybe you’re missing some backing plate parts that connect the generator to the fan housing. There’s several parts, maybe I can find you a pic, or maybe someone will post an exploded view of it for you.

There’s lots of fan belt information in the engine forum, just search “fan belt” and click the title only box.

Here’s one:
https://www.thesamba.com/vw/forum/viewtopic.php?t=569556&highlight=fan+belt

Generator thread from tech tips:
https://www.thesamba.com/vw/forum/viewtopic.php?p=8116434#8116434

Photo taken from the gallery, first one I found.

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[Wildthings]

Is the nut tight when you go back and check the belt and find it loose? It should be.

[richparker]

[Wildthings]

[Abscate]

It’s easy to mess up 38 amp and 30amp,generator and pulley parts, and if you don’t have the right set the pulley will get loose from side load. Make sure all those parts belong together. Pull them off, right down part numbers and post up.

These applies all the way to the fan housing end , too.
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[Brian]

I'll bite, whats the part number of your generator? The pulley feel like stamped steel?

Who has seen a stock 30 or 38 with a factory belt? Weird af compared what we see now
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[telford dorr]

It looks like you have a cast iron front (nearest to the generator) pulley. Hopefully, this is paired with a 38 amp generator mounted on a dished fan tin...
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[airschooled]

The sharp/machined lip on the inner pulley gives it away as cast iron.

chris86uk, are you looking for the best, quickest, or cheapest solution?

Robbie
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[aeromech]

Isn’t there supposed to be a certain amount of shims used? You vary the combination to achieve a tight belt but you always need to have a total of 7 or 8 (can’t remember) shims or else your nut will bottom out on the shaft threads
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[airschooled]

[busdaddy]

It looks to me like there's no shims between the pulley halfs and they are all under the washer, yet the belt isn't getting tight enough. That outer pulley half looks a bit odd, usually it's the same diameter as the inner on a 38a, that one looks slightly bigger, is the mix of parts messing with the belt gap?
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[Eric&Barb]

Is the crankshaft pulley the 7" OD? If smaller, it is an earlier pulley and not good for the DH cooling system for a bus.
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