Disco 1 Serpentine belt shredded after alternator change

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KNine

KNine

Active Member
Posts
149
Location
Salisbury Plain
300tdi D1 year 1998

Hi, I was hopping someone could help diagnose why my alternator drive belt has shredded after about 100miles after fitting a new alternator.
In the photo you can see that I have placed a steel ruler to sit on the inside edge of the pulleys. It is sitting in the Fan pulley and in the PAS Pump Pulley nice and flush, but when it gets to the alternator pulley it sits outside with a few mm to spare. When i fitted the replacement alternator, i did not see ant washers or shims to push it out and am not even sure if that is possible.
I would be grateful if anyone can advise on this issue, thanks, Darren.
 

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This is not the only answer you will get, and far from the best, but have you kept the original alternator? Cos if so you can get it rebuilt, cheaper than a new one.

Or take the new one off, take it and the belt and the old alternator to where you bought the new one from , tell them they sold you the wrong one as it obviously doesn't fit, they can see the two alternators side by side. Then under consumer law you are entitled to a refund or one that fits properly.

Obvs if you just ordered one from the internet, then things are not so clear.

Despite having a 300tdi, I do not know if there are adjustments you can make with shims or the like to get the pulleys in line. You do seem to have some idea but without being able to see the alternator and how it is mounted I cannot tell you. And my 300tdi is under a big tarp, tied down very intricately, which i am not going to take off, as others on here will be able to help you more easily than I can.

Hope you solve it with one or a combination of these ideas or others from others!
Good luck!:):):):)
 
Stanleysteamer said:
This is not the only answer you will get, and far from the best, but have you kept the original alternator? Cos if so you can get it rebuilt, cheaper than a new one.

Or take the new one off, take it and the belt and the old alternator to where you bought the new one from , tell them they sold you the wrong one as it obviously doesn't fit, they can see the two alternators side by side. Then under consumer law you are entitled to a refund or one that fits properly.

Obvs if you just ordered one from the internet, then things are not so clear.

Despite having a 300tdi, I do not know if there are adjustments you can make with shims or the like to get the pulleys in line. You do seem to have some idea but without being able to see the alternator and how it is mounted I cannot tell you. And my 300tdi is under a big tarp, tied down very intricately, which i am not going to take off, as others on here will be able to help you more easily than I can.

Hope you solve it with one or a combination of these ideas or others from others!
Good luck!:):):):)
Click to expand...

Thanks for the quick response. Good call, Just been outside to compare the old alternator with the new but they do actually seem to be the same size. I was doubting the alternator as it is not LR original. Also with the naked eye, the pulleys didn't seem to be aligned, but that may be an optical illusion. That ruler i placed between the pulleys (thanks to your reply) i have just checked and it was actually not straight (Red herring - Doh)
I will put the new belt on now and see how things run, but cannot explain why the last belt shredded and was thrown off (ERR5811R Bearmach)
 
The leftmost half of the alternator pulley is darker, possibly from rubber residue or heat from friction, which might indicate that the belt was slipping. Check that all pulleys rotate freely, that the tensioner is not weak and that the alternator shaft turns straight on its axis.
 
NPG said:
The leftmost half of the alternator pulley is darker, possibly from rubber residue or heat from friction, which might indicate that the belt was slipping. Check that all pulleys rotate freely, that the tensioner is not weak and that the alternator shaft turns straight on its axis.
Click to expand...

Thanks NPG. I think I may have work out some of the problem. So just tried to fit new belt (ERR5811r) which is the belt size i normally use. There was no way it was going on, I don't know how I fitted a new belt when I fitted the alternator. Anyway, Just discovered that the new alternator pulley is 6mm in diameter lager than the original, so I now need to start using (ERR3287) which is the larger belt. Just ordered 2 so will need to wait a few days now :-(
 
KNine said:
300tdi D1 year 1998

Hi, I was hopping someone could help diagnose why my alternator drive belt has shredded after about 100miles after fitting a new alternator.
In the photo you can see that I have placed a steel ruler to sit on the inside edge of the pulleys. It is sitting in the Fan pulley and in the PAS Pump Pulley nice and flush, but when it gets to the alternator pulley it sits outside with a few mm to spare. When i fitted the replacement alternator, i did not see ant washers or shims to push it out and am not even sure if that is possible.
I would be grateful if anyone can advise on this issue, thanks, Darren.
Click to expand...
Did you use the old drive belt again?
Over tightened?
Friend had a drive belt destroy itself and it turned out to be a stone or something like that wedged in between the bottom pulley and the belt.
Alignment shouldnt be out unless wrong alternator used.
 
KNine said:
Thanks NPG. I think I may have work out some of the problem. So just tried to fit new belt (ERR5811r) which is the belt size i normally use. There was no way it was going on, I don't know how I fitted a new belt when I fitted the alternator. Anyway, Just discovered that the new alternator pulley is 6mm in diameter lager than the original, so I now need to start using (ERR3287) which is the larger belt. Just ordered 2 so will need to wait a few days now :-(
Click to expand...

You're probably spot on. Just did a search for the 100A D1 alternator AMR5425 and they seem to sell them with either 49mm or 61mm diameter pulleys. Can't say why as I don't have a D1 but somewhere down the line they must have modified the specs to change the alternator speed.
 
Two things.
One. Mine is a Anniversary with air-con. Maybe the alternator is different from one without aircon? Prolly not but you never know.

Second thing, the idler pulley often gets dodgy and can be seen to not be running true, i.e. not in exactly the same plane/alignement as the rest of the system. There is a bush mechanic's cure, take it off and behind the mount put washers(s) coin, whatever until you move the mount out just the fraction it takes to properly align the idler pulley with everything else. Did that to mine and no harm came of it. Obvs just a simple thing as if it really is fubar you should get a new one, but if this is the problem it'll get you around for a bit!
 
Thanks Bantam1, NPG, Stanley steamer. I haven’t been on here in ages, so it’s great to get your thoughts Ideas. My car is probably the same spec as Stanley steamer, it’s a late jap import with air con, ABS, Auto, electronic fuel pump. I did change the idler about a year ago, but tbh the new one had just as much play in it when it came out of the box. I am hoping now that the longer belt will be a better fit and I may need to put a new bearing into the original idler at some stage and re fit it. I think the idler is pushing the belt a bit as NPG noticed the dark part on the outside threads of the pulley.
Thanks everyone
 
KNine said:
Thanks Bantam1, NPG, Stanley steamer. I haven’t been on here in ages, so it’s great to get your thoughts Ideas. My car is probably the same spec as Stanley steamer, it’s a late jap import with air con, ABS, Auto, electronic fuel pump. I did change the idler about a year ago, but tbh the new one had just as much play in it when it came out of the box. I am hoping now that the longer belt will be a better fit and I may need to put a new bearing into the original idler at some stage and re fit it. I think the idler is pushing the belt a bit as NPG noticed the dark part on the outside threads of the pulley.
Thanks everyone
Click to expand...
Mine doesn't have ABS or auto, or an electronic fuel pump but then if it is auto it has EDC so is a very different animal!
It wasn't the play in the idler, it was the way in which it didn't align which is very bizarre but apparently quite common, which was the issue and made my belt squeal until i sorted it in the manner i posted. Do have a look at this as it is a known fault.
Best of luck, mate!
 
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