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300tdi odd belt wear?


Maverik

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Hi folks, investigating the canary under the bonnet and I've found this, anyone got any thoughts? I've got an idea of what I think it might be but...

The belt seems to be wearing in a peculiar way, there's a fine black rubber dust appearing around the housing on the alternator and water pump next to the pulley. And after removing said belt you can see collections of rubber in the channels on the pulleys, but there are no massive chunks out the belt, just those funny flakey bits...

20170911_191152.jpg

20170911_191143.jpg

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Nope everything is as free as a free thing, that belt wear seems to happen at small patches along the whole belt not just in one area, it might be more on one side of the belt but you see the flaking across it too so not just down one set of grooves etc...

 

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Ohh the beauty of the Serp setup on a 300 :D I have just been trough this with my parents 110", and their belt looked a lot like that, after a lot of swearing and measuring we finally found that the recently (about 6 months) changed Alternator wasn't running true to the other pulleys, so after some time on the lathe everything ran fine Again and no noises (until the Next time) :D 

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I had wondered as the pulleys are all pretty tired looking as there was a bit of surface rust on them after the vehicle had sat for so long without being run, I wondered if the pulleys where a bit rough and they where chewing at the belt, they don't seem quite as bad now after a 1000 miles or so of running, anyone any tips on how one starts to check the alignments?

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It's called belt pilling and I've had at least ten 300tdis and have faught / fixed it for years! It's the reason why lots have the terrible squeak, nothing to do with the usually blamed tensioner.

Out of line alternator is the usual suspect, especially pattern alternators, I've had to shim them with three M8 washers before to get them in line. Lack of use causing rusty pulleys, worn pulleys, cheap water pumps and failing bearings also cause it. 

Ive had a 200,000 mile plus 300tdi that would eat belts, that had worn pulleys with the peaks being knife sharp and cutting through the belt.

Others would have lots of embedded debris on the top smooth surface of the belt - I think this is also caused by out of line pulleys but also rusty / worn tensioner and power steering pulleys - the out of line grooved pulleys cause the belt to enter and exit the smooth pulleys at an angle. If the smooth pulleys are rusty and pitted it abrades the belt and causes debris.

Ive tried cleaning out belts but if studied carefully usually one side of the groove is worn past the velvety surface and down to smooth rubber. Once cleaned out they tend to run quiet for a few minutes then the debris starts to build up again. Best bet is to attempt a cure such as realign alternator or replace worn pulley, then fit new belt.

Look at alternator and waterpump pulleys first as these also spin faster and more potential for wear. They are also closer together so less chance for belt to naturally deflect and correct slight misalignment.

If the tensioner jumps up and down at idle it is indication of belt debris.

My current 300 has just started to show debris in the belt grooves so I have just treated it to a brand new Denso OEM alternator which came with new pulley prefitted, and being OEM hopefully it will be correctly aligned. Also fitted a brand new genuine tensioner, new power steering pulley and belt. I will also treat it to new idler and waterpump pulleys shortly.

 

Edited by oneandtwo
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So, oneandtwo, with all this experience does that mean I have finally found someone who is willing to admit that perhaps the V-belt setup of the 200 was better? It seems like everytime I suggest it to people they quickly snap into defense mode and praise the Serp setup to the skies. Main argument is that they don't have to tighten the belt when it gets worn. Fair point, however if you add up all the time you spent fiddling with removing that terrible squeek you'll have spent twice the time it took to tighten the belt every 5 years :D 

The problem my Old man had was that the new alternator didn't come with a pulley, so he just used the old one.. But apparently the new alternator was different in a way that pulley didn't line up, it was something like almost 3mm's so quite a lot

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Well after a cleaned up the pulleys post photo's the thing is now howling and its a pretty unpleasant noise if you get close to it, and it sounds like its coming from the water pump pulley. I've got a new alternator pulley coming as well as a couple of belts, new water pump pulley and already got a PAS pulley, will get the new bits put on it and see if I can see where any miss alignment is.

 

On the topic of the V-belts, yeah the 200 seems a lot less prone to squeaking belts, but the fan belt is undersized for its job, and if you get the tension just a little bit wrong, or the pulleys get too old, then you go through belts at a rate of knots, especially if you've got a more appropriate alternator rather than the piddle standard fitment ones.

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The howling is generally caused by the unevenly worn belt. If you put a new belt on it odds on it won't howl until it's worn again. Likewise you can put a worn belt on a perfectly aligned engine and it will howl.

I still prefer the 300tdi, my experiences are spread over at least ten different engines. These engines never howled when they were new - it's generally cheap pattern alternators and water pumps causing it.

my Puma had the same worn belt howl when I bought it, had to change the tensioner and idler bearings and put a new belt on it, lovely and quiet now.

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Yeah there's no doubt a serp setup is better at transferring power, back in the day they would fit 2 or more V-belts for that. And it isn't a general knock on the serp belt, its just that on the 300 there's a lot of problems with it. I have never met a 300 owner that hasn't had some sort of problem with belt. Whereas I have met plenty with a 200/2,5NA/2,5TD that hasn't had any problems whatsoever with the belts

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9 minutes ago, elbekko said:

I had many problems with my 300TDi, but the belt wasn't one of them as far as I can recall.

Haha if the problems you did have was the usual overheating or carp vacuumpump I bet you wish it were just belt problems? :D So you're telling me it didn't even have a single squeek from the belt? ;) 

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Just now, Soren Frimodt said:

Haha if the problems you did have was the usual overheating or carp vacuumpump I bet you wish it were just belt problems? :D So you're telling me it didn't even have a single squeek from the belt? ;) 

Pretty much, yeah. So much overheating.

Never noticed the belt squeaking. I replaced the idler pulley at some point, that was squeaking a bit.

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4 hours ago, Maverik said:

hmm I think the operative word for me is water pump... I changed this out prior to getting her on the road last year, I think its a QT pump but not sure.

The Quinton Hazel pump is the problem. They were good once but not any longer - I tried one a few years ago and it failed within months- 

Airtex OEM are the best.

 

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Ok, I removed the belt and fan etc, a fastened a laser pen to the boss of the past pump (without pulley) (with blue tac...) I then rotated it around until it hit each pulley, the result was that the inner points of the pulleys all lined up correctly, i.e. the laser hit the same groove on all pulley, so this tells me at least the pulleys are all alighned on the same plane, I've not worked out how to prove the pulleys are then perpendicular to that plane, but it's maybe a reasonable assumption they are..

So further head scratching I found something odd, appears there is a slight ding to the inner edge of the water pump pulley, which appears to tie it too the inner side of the belt being warn. Popping a new belt on you can see the belt obviously shifting when it goes past the dinged area on the pulley, would this be enough to cause the belt damage in the pictures?

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1 hour ago, Maverik said:

Ok, I removed the belt and fan etc, a fastened a laser pen to the boss of the past pump (without pulley) (with blue tac...) I then rotated it around until it hit each pulley, the result was that the inner points of the pulleys all lined up correctly, i.e. the laser hit the same groove on all pulley, so this tells me at least the pulleys are all alighned on the same plane, I've not worked out how to prove the pulleys are then perpendicular to that plane, but it's maybe a reasonable assumption they are..

So further head scratching I found something odd, appears there is a slight ding to the inner edge of the water pump pulley, which appears to tie it too the inner side of the belt being warn. Popping a new belt on you can see the belt obviously shifting when it goes past the dinged area on the pulley, would this be enough to cause the belt damage in the pictures?

That's weird, maybe someone have tried to hold it with something when loosening the bolts the last time it was changed? Anyways good news that it runs true :) 

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Some interesting reading. 

Looking closer at the pulleys, they're rough as anything, I think I'll be changing them all out in due course.

I've just done the PAS pulley, got a water pump and alternator pulley coming, might have to set my laser up again to make sure they're properly aligned... 

Fan idler looks to be the most pricey.

 

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