1991 8v PB, standard set up. Ignore missing covers etc. just test fitting at the moment, will all be apart again. New Water pump / PAS pump, correct to car and fit perfectly. Original VW pulleys all round. First image is without V belt and PAS Pump is at its furthest extent of adjustment on bracket (pulleys greatest distance possible apart). Second image is V belt on and PAS Pump at the opposite extent of its adjustment on bracket. The Water pump / PAS pully are touching. V belt is new Bosch 1 987 947 790 (10 x 730) Have seen a couple of other brands stating they're 732 and 735mm. Only way to get it on was to remove both pump pulleys and a lot of jiggling. Wouldn't have been possible to get it over both other wise. I realise it may be tighter when new, but even so this seems excessive. Since images were taken the adjuster bolt has been fitted and I've managed to screw it down about 1/3 of the travel. Reluctant to go further as it feels on the verge of giving way / stripping thread. Pulleys are now about 1mm apart... is this to be expected, doesn't seem to be much room for error?
Never had any issues fitting the belt myself, and never had the pulleys so close. Were the pulleys powder coated by any chance? Any reason you don't want to just fit a longer belt? Gates suggest a 10x732, that's what i have used.
All new to me, first time doing this extent of work on an engine... scary and maybe being over cautious plus wadding through manuals and on-line references that never seem to say the same thing doesn't help. Main one I've access to is 7Zap, and if I've understood correctly 730 is correct to a PB with PAS. Autodoc and others seem to confirm this with 99.9% of brands quoted as being this length. As you say there's one or two oddities like the Gates at 732 and a Delphi at 735 (that one even goes so far as to specifically state its for PB's). Going to put the old PAS pump back on out of curiosity... dumped the old belt unfortunately, would've probably answered things straight away. When I say the pullys are touching, they're actually pressing together. The adjustment screw makes no difference for quite a few turns before the smallest of gaps appears. Must be a nightmare of a job when everything's on the car and not a stand. Going to get a 735 to see, thanks for reply.
I've had the same thing with mine using that belt. I think I tightened it up a little bit more and ran it. After 100 miles it needed a fair bit more tightening and had a more reasonable gap. However, like you, it was horrible to get on initially "this can't be right" sort of feeling.
How much tension is on the belt? Make sure the top pivot etc is a bit loose when you adjust the adjuster, otherwise you'll be working against that too
It's excessively tight at the moment, to the point if I loosen off bolts elsewhere the PAS pump goes out of true with the water pump pulley... Over and above the miniscule gap it may even be putting the shaft / bearings of the pumps under undue stress?
Well, put the old PAS pump back on and belts still just as tight, bizarrely if anything a worse fit overall. Juggled different combinations of tightening / loosening all the bolts involved with the water pump / PAS / brackets etc... nothing truely works. Most worrying is they all to some degree or other leave the PAS pulley just a little bit out of kilter with that of the water pump, I'd image they'd both need to be in as perfect a balance / alignment as possible but the belts straining them out of true. There must be more give in the V belt than you'd imagine, using the bracket adjustment screw I get to about halfway through the range of travel before you see any discernible gap at the pulleys. It's got me wondering, in light of what has been said above, that with use it'll likely loosen up and potentially end up with the opposite problem... with just the remaining half to go, run out of adjustment. Need to balance which length to go for and 732's the one in the middle. Different belt size it is then, will keep plugging away and keep you posted - thanks for input!
What pulleys do you have for the water pump and PAS? There are two sizes...037 145 255 which is 105mm dia. and hard or expensive to find. The other is 027 145 255 which is 99mm dia. (also available as Topran 109 645 from B&B on ebay.....https://www.ebay.co.uk/itm/221582011714?hash=item3397512d42:g:dSsAAOSwZcJechqc If both of yours are the 105 dia. it might be an idea to swap one for the 99 dia. version. I have one of each on my PB engine and about 5-10mm clearance between the pulleys. edit... washers on the pulley bolts can help with the belt alignment!
Tbh, you're probably over thinking it a little. Put on the next size up in a belt, run the engine for a while, and recheck. I will be shocked if it doesn't need a slight extra tightening.
The water pump pulley is 105mm and the PAS is 96'ish, though was using a steel ruler so probably not spot on, but definitely smaller. The pulleys themselves are both tight on their shafts, it was the entire PAS pump that was being drawn away from the vertical by the belt tensions. Have it all set up 100% now (less the belt) and everything is perfectly in line / balanced so good starting point for when the longer belt arrives. It's surprising how even the smallest change to a combination of the various bolts, including the water pump bracket ones can distort the pulley position, took a bit of effort back and forth getting them sorted... hat off to you if you do it while still on the car!
whats the part number on the crank and waterpump v-belt pulleys. looks like one of them is incorrect. pas pulley is correct 027145255 edit: looking at above pic think crank pulley is 026105255D? if so thats fine too. waterpump pulley should be 027121031A
surely if you have not replaced the pulleys and it was alright before you took it to pieces it must be the belt that is wrong. I might be thinking a bit to simplistically.
Water pump pulley has a very slight offset, the part numbers etc. are on the face away from you in the image, maybe why it looks odd? If it's put on with those numbers facing outwards the pulleys 'V' doesn't line up with those of the crank and PAS pulleys. The PAS pulley must be equidistant front and rear as it lines up with both the others regardless of how it's put on
ok all fine then, can only be belt is a little too tight I guess... bit of string round to confirm? though if its bosch you should be sorted
String - Good idea! As a rule I usually keep everything that comes off, exactly for reasons like this, but stupidy binned the one that was on. Mentioned above putting the old (original) PAS pump back on, positionally everything is identical with the new Meyle so pretty happy it's solely a belt length thing, cheers.
Let us know what the string finds, I also fitted a Bosch belt around a year ago and has the exact same issue as you as mentioned.
Tried it over and over on the day of the post, but couldn't get the same measurement twice. Tried again today but with strimmer twine as it's more rigid, but just as much variation. Wasn't sure if it was to be taken from the bottom of the 'V's or the top of the rim of the pullies either, or somewhere in between. Then realised none of that matters as it'll all depend on where the adjuster was set originally and that's an unknown.
