Slight snag when replacing exhaust. What to do?

[Hoopy_Frood]

Woo hoo.. Getting my hands dirty at last.

I've removed the old exhaust, some of the pipes were attached to the engine using studs and some had big bolts either threaded or bonded into the old stud holes with a nut holding the pipe in place. Now one of the bolts won't thread back into its hole. I must have either stripped it or removed whatever was holding the bolt in. It did have a dry white residue on it when it came out.

What are my options to fix this?

Thanks
Iain

[kevtherev]

try cleaning out the bolt hole with a thread cleaning tap.
you can get these singly or in sets

alternatively you can take the hole to the next size up by drilling out the old knackered thread and re threading it to the next size.

or even having the hole alloy welded up and redrilled to the original size.

[Hoopy_Frood]

Thanks Kev, I'll try cleaning the thread first. This is my first real job on it so I'm hoping to avoid taking the engine out already.

[itchyfeet]

If you end up drilling for a helicoil or m8/M10 stud then don't forget your depth guage

https://club8090.co.uk/wiki/Pe ... stud_depth" onclick="window.open(this.href);return false;

http://m.vwheritage.com/productDetails. ... mID=118032" onclick="window.open(this.href);return false;

[Hoopy_Frood]

Hi Itchyfeet,

Forgive my ignorance, but how do the new studs in your link stay in place? Will something like a thread lock compound be sufficient to keep the 10mm threaded bit in the hole?

Thanks

Iain

[kevtherev]

It cuts a new thread for the insert
I prefer Timesert.. google it

[silverbullet]

It's worth having a few standard metric taps & dies in your toolkit such as M5,6,8 &10 will see you right, along with a tap wrench and die stocks. Don't buy cheapo Chinky or used taps, if they have been dropped or strained they can snap off and leave you on the poop.
If you've only got one or two stripped on the heads, clean them out first then consider calling a local "thread doctor" out to put in a helicoil or timesert, it's not really a job for the inexperienced and even (not so) old hands can get it wrong sometimes...a certain knack is required and when access is limited, you need everything on your side!
Best of luck

[itchyfeet]

Hi Itchyfeet,

Forgive my ignorance, but how do the new studs in your link stay in place? Will something like a thread lock compound be sufficient to keep the 10mm threaded bit in the hole?

Thanks

Iain

The stud in the link has an M8 one end and an M10 the other, the intention is you drill out with the correct tapping drill size ( not too deep see the picture in the other link) and tap the hole to M10 and then screw it in.

What keeps it in place is just friction, as you add the nut it could screw it's self in a bit but the friction on an M10 stud is greater than on an M8 nut so it will tend to just stay there. When you come to remove the nut in future it's possible the stud will unscrew before the nut but that's not really a problem and can happen on the M8 studs. Don't use threadlock the temperatures are too high and it's not needed. Do use copper or stainless steel nuts.

As said above drilling, tapping is something you will ideally have some experience with or you could get it wrong, it's not that hard when you know how. If you do decide to have a go then find a lump of aluminium to practice on first . I'm sure there are video's you could watch to learn. If you got this far removing the exhaust then I'd say you have ability.

[Hoopy_Frood]

The hole has previously been drilled for a 10mm bolt, so I would need to go even bigger still. I've bought a clarkes tap and die set from Machine Mart and will see if the 10mm tap can clean up the threads, otherwise I'm guessing it will need drilled out to M12?

[kevtherev]

time for a timesert..

12mm is too far

[Hoopy_Frood]

Post by kevtherev » 18 minutes ago

time for a timesert..

12mm is too far

I couldn't find them at Machine Mart and I kinda want the van for this weekend. I picked up the clarkes version of the helicoils in M10 flavour as a fallback plan if cleaning the threads doesn't work.

[silverbullet]

That'll be OK, it'll get the M10 repaired. Remember to break the helicoil driving tang off with a sharp tap from a pin punch, about 5mm dia and square ended. Never leave the tang on, it can lock the bolt/stud solid, should you even need to get it out again. Best of luck.

[Hoopy_Frood]

Hooray. I am almost done.
The previous holes were still 8mm (not 10 like i thought) so I ran the 8mm tap gently down the hole and it has done the trick. Thanks for the advice. I have one annoying nut near the oil filter left to tighten and for the life of me I can't seem to get at it as easily as before. I reckon daylight might help. A headtorch isn't really enough light and I'm knackered anyway.

Cheers

Iain

[itchyfeet]

well done

I know what you mean about that fixing it's not one of VW's best designs