Mk5 2.5di.. Shearing alternator mounting bolt..

[HiRoller]

Put a new alternator in my van a few months back..

Last week it sheared off the top mounting bolt. The one that goes through the adjuster block and into the alternator body...
I replaced it with (an admittedly crap quality) a bolt from Halfords..

This snapped after a week...
Any ideas why this is happening?
The alternator doesn't have a freewheel and it is tight and the belt has the correct amount of deflection..

[transitjack]

is it lined up right ie is the alternator in line with the bracket

[kanicchi]

Hi,
i think the problem is that alternator has a very tight position on the bracket which is centered in the bore for bolt with "some kind of step pipe" - on my quick picture it´s the red part. I don´t know if it´s some pipe pressed on to alternator bore. The bolt is not strenght shaft, the bolt is only pressing the bracket which is holded with this step pipe. Sorry for my english, I hope you understand what I mean.

I worked on my alternator yesterday - so I know it. I have 1999 2,5Di.

R.

[madbri]

my money is on the bottom bolt where it gose through cases it gone overal common problem

[BUNGAL]

The bottom mount has worn, it's in two halfs the rear is removable but the front is part of the front casing, still removable but a lot more work, I have drilled mine out, to 10mm and fitted a new bolt,


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[V184]

The bottom mount has worn, it's in two halfs the rear is removable but the front is part of the front casing, still removable but a lot more work, I have drilled mine out, to 10mm and fitted a new bolt,


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From memory the hole in the front casing is oval ?

[madbri]

The bottom mount has worn, it's in two halfs the rear is removable but the front is part of the front casing, still removable but a lot more work, I have drilled mine out, to 10mm and fitted a new bolt,


Sent from my iPhone using Tapatalk

From memory the hole in the front casing is oval ?

if its worn. ment to be o shape

[bambi mk 1]

Oval doughnut Madbri

[V184]

The bottom mount has worn, it's in two halfs the rear is removable but the front is part of the front casing, still removable but a lot more work, I have drilled mine out, to 10mm and fitted a new bolt,


Sent from my iPhone using Tapatalk

From memory the hole in the front casing is oval ?

if its worn. ment to be o shape

Cheers for that i thought the oil pump cover was round & the rear bracket with the steel insert .

[Peterr]

I was plagued with this. At first every 1-2 months the bottom bolt would shear. Eventually I replaced it with a larger diameter bolt but this would last 3-4 months. I went through several alternator housings and eventually I had to rebuild the mount with steel plates and larger diameter bolts. It was a nightmare and it would always fail during long trips home. (Though I must say that ol' van ALWAYS got me home even if it had to limp all the way back, and safely carried me a half million km LOL) The alternator issue was a real headache and no matter what I tried it would always shear to the point that the lower bolt made the mounting hole on the engine oval and thus I was forced to rebuild it. The rebuild worked great. No more sheared bolts. But now every 5-7 months the nut unscrews itself, even lock nuts. I imagine this has everything to do with having only 3 mounting points arranged in such a way as to produce vibrations that chew up the bolts and mounts. As it gets worse the frequency of shearing becomes a regular occurrence. My next step was to add a stabilizing bracket but still haven't figured out where to put it because the alternator needs to be adjusted for the belt tension, thus an extra bracket must adjust with it too. Good luck!

[Aardvark]

Long term problem for me as well. I kept upgrading bolts up to grade 10. I'm now using 316 stainless ones. They last quite well but I still carry several spares of the full set.

[Peterr]

Long term problem for me as well. I kept upgrading bolts up to grade 10. I'm now using 316 stainless ones. They last quite well but I still carry several spares of the full set.

LOL There must be a whole army of us carrying a tool box and a box of long bolts and an extra alternator, traveled for years like that. Saved my butt plenty of times.

[Aardvark]

I ran out of bolts once on a long trip and ended up keeping the alternator in place with rope. It lasted a couple of hundred miles. I was tempted to just leave it like that.

[Peterr]

No kidding, carried an extra alternator, tools and bolts for years!! Unfortunately but fortunately was always able to fix it on the side of the road, a nagging pain.