[Zebedee]

Has anyone got any experience with the alternator casting fracturing on post 1999 Thor engines where the serpentine belt tensioner is attached?

I have had 2 go in the last 8-months. They have both fractured and pulled out a 3 inch disc from the casting - with the serpentine belt tensioner still attached.

The first I thought must have just been the original was a bad casting. However, to have a second one go only 8 months and 10k later seems to be too much of a conicidence. I also thought that the tensioner might have partially siezed on the original one, which could have put too much loading on the casting (as can happen on the TDi Discoverys), so I put a new tensioner on. The replacement casting was a 2nd hand one, rather than new because of the price of new ones, so that could have been faulty too.

Any thoughts or suggestions would be appreciated. Thanks.

 

[viperover]

Fractures, cracks and breakages can be caused by a number of issues.
Inferior replacement with a non brand cheap knock off type. (stuff from the east)
Incorrect fitting, forced on/knocked on with a hammer.

Then the best bit, vibration which can come from numerous other components including prop shaft.

 

[Zebedee]

Local LR breakers seem to know of this problem and have all asked if the casting has cracked around the serpentine belt pulley. One went as far as to say that the casting lasts only about 100k! The original casting had done 130k, and I've no idea about the 2nd hand replacement.

I've found 2nd hand one at a breakers for £45, or the dealership has got a new one for £65 plus VAT - so I've gone for the new one...

 

[Zebedee]

I'm surprised no-one else had any experience with problems with this part.....

The new part from Landrover is currently on backorder, there are none in the UK, and they don't know when there will be any more from the supplier. I've sourced a 2nd hand one and, yes you've guessed, it is cracked around the mounting for the serpentine belt tensioner. The options now are either to get the cracked one stitch welded, or to find another one that is in better condition.

It seems as if the casting thickness is reduced to about 3mm at the back of the casting in this area (presumably to save a few pennies of Aluminium) and this fractures from the vibration of the tensioner. If you've got a post '99 Thor engined car, be aware of this as the tensioner can cause a lot of damage as it rattles around between the radiator/fan and the engine.

 

[kmagnuss]

I'm embarrased to say that it happened to me. Not because of a bad part, but because I torqued the ever-loving-**** out of my alternator when I took it off. Replaced it with a OEM part ordered from the local LR dealer, and all is well.

 

[kmagnuss]

golly gee whiz = ****

 

[Zebedee]

As there doesnt' seem to be much on this forum yet about this problem, I thought I'd include some pictures of how the part fails, and also a picture of the 2nd hand part that has circled where the crack is beginning to develop.

This is only 3mm aluminium at this point and does seem to be a weakness.

 

[viperover]

I would have thought poor casting quality would be to blame, then also over tightening the tensioner would over stress this area too.

 

[RapidZer]

I know someone that experienced that alternator casting fracturing on post 1999. He is a friend of mine. The problem is we are far from each other. I will try my best to contact my friend as soon as possible.

 

[kmagnuss]

Good to know.

 

[viperover]

If it happens again I would do a repair, judging by the pics its easily done.