Mk5 Sheared Alternator Belt Tensioning Bolt

[PianoVanner]

Hi all,

I've used various forum threads for fixes over the past few years, but this is the first I've posted - hopefully you can point me in the right direction.

I've got a 1999 Mk5 2.5di that I've converted from a Mr Kipling's delivery van to a self-build campervan (with a piano in it - hence the member name). It's just done about 2k miles around S.Wales and Ireland on a 10 week trip, and other than waiting 12 days in Bundoran for a new accelerator cable after mine snapped, it's done pretty well (if embarrassingly slow on some of their steeper hills).

During the last month of the trip it's had a slipping alternator/serpentine/drive belt and has squealed its was down the road each time I left somewhere! Now back in England, I've made an attempt to tighten it and slightly ballsed it up. I loosened the bolt that holds the alternator in the slot, then tried to tighten the tensioning bolt that runs through the block [/img], but as it was near its limit already, I pushed it too far and succeeded in shearing the bolt. So my questions are twofold:
1) Could I use a stainless 8mm x 100mm bolt, or is it a special high tensile or thread specific bolt I've got to track down?

2) When it comes to tightening the belt, does the tensioner being at its limit mean the belt was stretched and I need a new one? It looks in reasonable condition - no cracks, and not much give though Haynes+Google say it should twist 90 degree and I can turn it a full 180.

Also, as I haven't really tightened or loosened the alternator or belt, I'd still be okay to squeal my way down to a parts shop rather than needing a lift, right?

Any help greatly appreciated,

Thanks

[metalworker0]

Well there are several set-ups with your motor ..
All things are a built with different options.. air con, different alternator, power steering, ptc heater , etc

See here and point out from the blue links the url which is yours
press English at top of page first NOTE: site not working with windows 7 and internet explorer

http://www.catcar.info/ford/?lang=en&l= ... IwNw%3D%3D

Yes stainless will do.. it's stronger than mild steel.

How to use site
You press on the number in the diagram .. and then it scrolls you down to the part description complete with info on the thread size and length and part number, for instance one says .. bolt hex m8 x 103mm on one diagram part number .1382115 FORD. dont know if yours but 11 on ebay cheapest £11.. you could use threaded rod .. which is available in: mild steel .. hi tensile and stainless. engineers merchants will have that selection .. B@Q you may be limited to mild steel.

NOTE: you cant copy the part number until pressing on it lands you on another page where you can copy

If you find the right diagram, it will give you the part number for the belt .. again maybe four belts on each link ..

all the best.mark

[Peterr]

By coincidence I'm working on the alternator today. I’ll post some photos later. I don’t think you need a special bolt, not that much tension will be placed on it when you tighten it. It’s important to loosen the swinging bracket that is bolted to the engine. The arm needs to swing while it is being pulled tight. Easy to forget that.

The mounting of the alternator will regularly fail. This is a chronic problem with these models. Usually the thin long bolt that is under the alternator that holds the alternator to the engine block through a small bushing will wear an oval hole in the mounting on the engine block. It’s made of aluminum so eventually the steel bolt will wear it down causing the alternator to start working at an angle. Check that the alternator pulley and belt are in line with the other pulleys and not at a slight angle viewed from the top. If you find that it is working at an angle you can temporarily place some washers between the sliding block and swing arm that pulls the belt when you tighten up the tensioning bolt. This will move the alternator slightly to correct the angle but it also adds stress on the swing arm bracket. Don’t leave it like that for too long.

The best solution is to have steel brackets made to place on either side of the long bolt under the alternator. This holds the long bolt firmly so it doesn’t wear against the aluminum.

Hopefully I will be able to do this today then I’ll post the photos.

Always keep extra bolts and brackets if you travel a lot. Easy to repair on the road and could save your day!

[Peterr]

Here are some photos in detail:

[PianoVanner]

Thanks very much, this is really useful stuff to know. I'll check out how the alternator's sitting today. If it is on the wonk, then I used to do metalwork (welded a new wheel arch, step, and various chassis holes), have a workshop filled with fun toys, and can hopefully make some supports.
I'll put up how I got on in a bit.

Cheers

[Peterr]

Workshop full of fun toys …. Wish you were my neighbor here in Italy LOL

Still didn’t find the steel brackets I made. Got lost in the move but I’ll keep looking. I’ve seen them around probably put them in a secure place where I don’t remember LOL.

Basically I used 4mm -6mm plate. Can’t remember precisely. Made two pieces that was the outline of the original aluminum piece as in the photo below. Can’t remember if I replaced the alu bracket or placed the two steel plates on either side and found a longer bolt. At the time I drilled a larger hole for a longer and wider diameter bolt. But you have to do that also through the alu engine part and through the alternator mounting ears. I don’t recommend drilling larger holes in the alternator ears because it will weaken them and possibly break. At the time I was traveling long distances and the vibrations kept breaking the long bolts. I was rather fed up and didn’t have much time I threw together two steel plates with larger holes and a longer stronger bolt. This held up for a few years.

Important: don’t tighten the long bolt so hard that it begins to squeeze the alternator ears together from either end, they will break. Use a nylon lock nut and washers to just tighten snug enough but not so hard that the alternator can’t swing up and down. It needs to swing up as you tighten the belt.

[Peterr]

Here’s an example of the alternator ear that had worn oval from vibrations. This is chronic and will drive you nuts.

[Altransit]

It was a long time ago now, but I'm sure that on my Mk5, I replaced the long bolt with two shorter ones. It meant that the worn hole no longer mattered, and I could align the alternator precisely, before tightening all of the bolts. It also meant that I didn't need to source a new long bolt, and used ones that I had handy!

[Peterr]

How did you fit two shorter ones? It has to go all the way through.

[Altransit]

How did you fit two shorter ones? It has to go all the way through.

It just pivots on the longer bolt, but fitting shorter ones just means that you have to release both bolts to adjust the belt.

It was a long time ago, but it must have worked as it was still there when I sold the van years later.

[Peterr]

Finally found my metal 4mm brackets I had made to reinforce the alternator’s long bolt preventing the aluminum bracket hole from becoming oval resulting in the alternator pulley working at an angle which will put excessive force on the tensioning bracket causing it to eventually break and the belt from heating up do to friction against the angled pulley causing smoke and eventually breaking too.