NiallRussell

NiallRussell

Well-Known Member
On my 300tdi I've just stripped (not even with any force!!!!) the thread for the aux belt tension pulley on the aux mounting bracket. The one where 8 goes into.

655_coolant_pump.gif


just had a look online for a new bracket and the prices are scary!! 230 - 250 for blue box ones, 320 for genuine. Any other options? I really don't want to buy a new piece just because of one stripped thread if I can help it.

cheers.
 
Can't see the picture but can you helicoil it? Or if there's enough meat around it, go to an m10 bolt
 
I was just looking at that. Having never used Helicoil... the hole does go all the way through, this ok with helicoil?

Can't get a bigger bolt through. It goes through the pulley with a snug fit.

655_coolant_pump.gif
 
Hole for item 8?
I've never tried a helicoil in a clear hole but it must be doable.
An alternative is a reducing stud, m10 on one end m8 on the other, you can buy them or a small machine shop could knock one up quite cheaply. Or a nut and bolt straight through if there's room, not familiar with the 300.
 
Helicoil dead easy to do with basic tools and way cheaper and easier than replacing the casing as it holds the alternator and power steering pump ,you would also need to do the P gasket while you were there
 
I bought a kit from carbonfibergeneration on eBay last week, good quality kit with quick delivery, so recommended.
 
Thats a good piece of kit!!!! worked a treat. very nervous torquing it up, but held fine.

A bugger to work in the area though and I got nervous about drilling while the piece was still in place, rather than taking everything off, but it worked well.
 
Porsche brake caliper bolts strip all the time and the approved method is to helicoil them. If it's good enough to secure the brakes on a 170mph sports car it should be fine for a belt tensioner.
 
The helicoil could even be stronger, because the bit that takes the friction from the threads of the male component is nice hard helicoil steel, whereas the bit that bears against the alloy housing is larger so would need to pull more metal away in order to strip. That was the original idea - so that you could have hardwearing threads in soft alloy components.
 
I've also used 'screw-lock' helicoils that have a built in thread locking system, handy when you need to ensure a stud or similar needs to stay put in a hot area (a head for example) but you don't want, or cant use thread locking compounds see page 4
 
I stripped the exhaust thread on the barrel of a bike

As at the time I had access to machine tools, barrel off drill and tap larger, drill and tap some rob, then cut down and external tap.

Usefull training course
 
Gota love helicoils I work in heavy plant as a salvage machinist so have a very good collection of them
all the way up to m60 lol most of the time they are stronger than the original thread
 
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