Loose Turbo Bolts - growing problem

**abreut** · 07-01-2010, 09:10 AM

Would be good if there was a type of gasket that was able to take up the expansion and contraction instead of the bolts having to stretch.

I think removing any exhaust weight load will help too.

Maybe we need water-cooled bolts so they don't get too hot

**Skywalker** · 19-01-2010, 02:14 AM

I recently stated hearing a rough idling sound at times from my exhaust..When theres even a slight press of the accelerator the sound cant be heard..but at idle i have noticed it. It started after i took car to a highish speed on one occasion i think. Is this loose turbo bolts? Or in the loose turbo bolts case is that sound one would hear from the engine bay?

Thanks!

**Jmac** · 19-01-2010, 08:32 AM

loose bolts would cause a dip in power and the noise would be more apparent when you accel, as the turbo is pressurising trying to create boost, which gets blown out of the gasket where the loose bolts are. This is why they sound like a tractor when it happens.
Jmac

**Skywalker** · 22-01-2010, 01:14 AM

Originally Posted by Jmac

loose bolts would cause a dip in power and the noise would be more apparent when you accel, as the turbo is pressurising trying to create boost, which gets blown out of the gasket where the loose bolts are. This is why they sound like a tractor when it happens.
Jmac

Thanks

guess thats not whats happnin with me (yet). Good to know

**woosh73** · 22-01-2010, 10:54 AM

Quote:
Originally Posted by woosh73
having a full time business on the side ( www.captain thread.com) problem : turbo bolts are loose. i caught up with h100vw ( top bloke ) . who showed me the problem

1. redo the thread with a helicoil to make the thread tighter
2. ( i would recommend this one ) - convert the bolt to a stud and use spring washers and nuts.

By the way if anyone wants anything fixed ( see my website ) mention that your a member and we'll look after you.

This is my business , my staff are experts in threads / bolts. This is the cheapest and the best way of alleviating the problem.
( Option 2 )
If you live in Adelaide and you have the problem give us a call. Then post up the result and the thread will stop.

Sorry about the forcefullness but we've done this before and it's 100% successfull.

**Jmac** · 23-01-2010, 08:03 AM

I thought about doing the stud and nut thing a way back but couldnt get 50mm studs for the job, also had one needing 70mm bolts as it is getting an ATP larger manifold coupled to it, even took it along to a couple of turbo places, also one bolt mob but they just had a blank expression and zero interest so gave it a miss, Ive done this repair to an XR6 turbo and worked well but havent heard of it being done to a Polo, be good to hear some feedback from someone who has as my lock device is a bit away. PLENTY of interested parties await the feedback
Cheers
Jmac

**woosh73** · 25-01-2010, 09:05 AM

You can get longer studs , and thicker diameter , we just cut the thread to suit.

**gldgti** · 25-01-2010, 09:35 AM

are all the VAG setups mentioned using M8 bolts? and they have a triangular flange right, with only 3 bolts or studs?

even my old T2 setup on my diesel had impressive DP bracketry, since the VW T2 flange was 3x M8 bolts (well 2 bolts and 1 stud). This isnt a lot considering the whole lot can glow well past cherry red if your really up it.

I'm surprised no-one has been gathering EGT data - i would bet money that this happens when cars spend certain lenths of time above a certain EGT threshhold. Why everyone that does a trackday in a turbo car doesnt have an EGT guage is beyond me.

anyway, from an engineering perspective all the evidence does indeed suggest that the setup is getting too hot and the bolts cant cope. you only need to go above 650*C before lots of things start to happen, creep sets in in the bolt material and even without an exhaust hanging off them, eventually they will stretch to a point at which theres no tention in them (while hot). depending on thermal expansion coefficients of the bolt steel and the manifold material, they may or may not still be tight once cooled down. evidence seems to suggest not.

forget the grade of the bolt, if they arent up to withstanding the temperature it doesnt matter how strong they are at 25*C.

the only way fo fix the problem at the source would be to change to larger diameter bolts as the thread man has suggested, or run a tune that results in lower EGT's.

**woosh73** · 25-01-2010, 10:22 AM

We have had huge success with the TD landrovers which had the same issues with the turbos and encreased the bolts on the exhaust manifold bolts with success.