VW T4 2.4D AAB engine 1992 - Helicoil Inserts

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Tue 27 May 2014 09:48
VW T4 2.4D AAB engine 1992 - Helicoil Inserts - Goose2000

Hi there, some advice needed if possible.

I am repairing and replacing an engine on a VW T4 2.4D AAB engine, and I have found the that the tensioner for the timing belt has had a helicoil put in where it must have stripped the original threads. Though now the helical is stripping the threads on the bolt I am trying to put in.

If I renew the helicoil what type should I put in? The mounting is Aluminium and the bolt is stainless steel?

I am just concerned about steel on steel as it seems to have failed once, and also as there is vibration in that area.

Thanks

Craig

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Tue 27 May 2014 12:37
VW T4 2.4D AAB engine 1992 - Helicoil Inserts - 659FBE

It might be worth your while making a search on this site as I have experienced (and reported here) ctastrophic difficulties with this tensioner stud.

Briefly, my findings have been that the VAG recommended torque is excessive and damages the threads - usually on the second or subsequent belt change. As these are long-lived engines and the consequences of a failure are dire, it's a very poor design by VAG.

A helicoil if correctly inserted should provide a strong repair, but it's essential to use the correct helicoil tap and to ensure sufficient thread depth. As it's a blind hole, you need to snap off the helicoil tang with the tool in order to achieve full stud engagement. Consider the use of a thread locking compound to ensure that the stud remains fully engaged with the head.

Consider also my suggestions for the tightening torque of the retaining nut on re-assembly.

659.

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Tue 27 May 2014 20:59
VW T4 2.4D AAB engine 1992 - Helicoil Inserts - Goose2000

659.. Thank you for the reply and the thoughts there, that has given me some food for thought.

I will be paying attention to the torque setting on reassembly, the 20deg will hopefully be suffice. Always a worry when dealing with this area of the engine.

The mount for these as you probably know is part of the oil pump casting. So if the helicoil doesnt work for what ever reason it will be a new pump, and funnily enough these arent cheap either.

As my old stud is knackered, would you know where I can source the correct one?

Loctite will be used of course. Fingers crossed!!

Thanks

Craig

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