Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: omegod on 15 March 2011, 08:05:16

Title: Down pipe misthread
Post by: omegod on 15 March 2011, 08:05:16
Well I seem to have made a schoolboy error when fitting a new gasket to the drivers side downpipe to manifold joint, due to the nightmare access( 3 extensions!) I seem to have misthreaded one of the 15 mm nuts and the thread seems mangled, resulting in it not sealing and blowing, it needs to be a fair bit further down the thread than it is :o

I guess the only option is to replace the exhaust manifold, OH F******CK ;D but I am happy to try ANY bodge that may work and get a seal on this joint so spanner wielders of OOF give me your best suggestions!
Title: Re: Down pipe misthread
Post by: Elite Pete on 15 March 2011, 08:16:03
Manifold off i'm affraid Jon :(
Title: Re: Down pipe misthread
Post by: mantahatch on 15 March 2011, 08:31:15
Is it worth trying a die of the correct size and trying to recut/clean up the thread ?
Title: Re: Down pipe misthread
Post by: omegod on 15 March 2011, 08:44:31
There is bugger all access, just about get a socket up there :(
Title: Re: Down pipe misthread
Post by: mantahatch on 15 March 2011, 08:48:19
Quote
There is bugger all access, just about get a socket up there :(


Remove downpipe/cat first and you should have reasonable access.  :y
Title: Re: Down pipe misthread
Post by: amba on 15 March 2011, 11:15:30
Possible solution would be to get a stud removing socket such as an Irwin on a couple of long extensions.

You will need to remove the cat to give yourself a bit more room to work,but you may then be able to free the exhaust stud from the manifold.That way you then can replace the entire stud and fit a new copper nut and seal up as new.

Sounds possible as you have little to loose,and will save removing the entire manifold.

Best of luck with it.
Title: Re: Down pipe misthread
Post by: Martin_1962 on 15 March 2011, 11:28:06
Copper nuts are used - is the stud thread OK?
Title: Re: Down pipe misthread
Post by: omegod on 15 March 2011, 11:56:42
Quote
Copper nuts are used - is the stud thread OK?

I think it is the stud thread that is mashed sadly! any type of nut available that will grip/cut it's way up? sounds daft but if the threads buggered it's a new manifold anyway so anythings worth a try just to rather seal it,believe me, I won't be going there again'!!!!!! one of the two nuts  is done up nice and tight but obviously needs to be well tight to seal.
Title: Re: Down pipe misthread
Post by: amba on 15 March 2011, 12:16:09
If you still have abit of thread on the start of the stud,would it not be possible to shim off the face of the exhaust flange with a few washers or an oversized nut and then get the copper nut to tightened up against them .?
Title: Re: Down pipe misthread
Post by: Cliffo B on 15 March 2011, 12:26:23
how about this?could be worth a try.go to your nearest engineering tool supplier and get die nut thread cutter then lock this in a socket and re cut the thread with a gentle twist untwist and plenty of oil,all depends if theres enough space to take the socket surounding the stud,hope this helps,best of luck
Title: Re: Down pipe misthread
Post by: omegod on 15 March 2011, 12:37:24
Quote
how about this?could be worth a try.go to your nearest engineering tool supplier and get die nut thread cutter then lock this in a socket and re cut the thread with a gentle twist untwist and plenty of oil,all depends if theres enough space to take the socket surounding the stud,hope this helps,best of luck

Sounds like a plan..Does anyone know what size thread the stud  is please?  :y
Title: Re: Down pipe misthread
Post by: JamesV6CDX on 15 March 2011, 12:40:59
As a short term bodge, if you have at least a nut's worth of thread on the end of the stud, just use some form of spacer(s) on the damaged thread, and tighten against the good thread.

Longer term -

Cat off --

Good soaking in plusgas

Attempt to extract entire stud.

If this fails, it's manifold off....
Title: Re: Down pipe misthread
Post by: alank46 on 15 March 2011, 13:06:09
Quote
As a short term bodge, if you have at least a nut's worth of thread on the end of the stud, just use some form of spacer(s) on the damaged thread, and tighten against the good thread.

That is what I would do.  As a spacer use the next size up nut, or the correct size nut with the threads drilled out.
Alan
Title: Re: Down pipe misthread
Post by: ffcgary1 on 15 March 2011, 16:03:48
If you go to your local Machine Mart you can buy some stud extractors that fit your extenstions, remove the stud and replace one or better still both studs and nuts with new. I have them and they are fantastic.
Title: Re: Down pipe misthread
Post by: Bent valve on 15 March 2011, 20:11:38
The thread size is M10 X 1.5.
Get a die nut this size thread it onto the stud and tighten it up hard. Then get an M10 Binx nut, which is basicaly an aircraft grade locking nut and tighten this up as hard as you dare against the die nut.
Both these nuts are readily available from your local engineers merchants :y
EDIT, I have just had a look at a spare manifold in the garage and there isnt enough space between the stud and the downpipe to allow a die nut and socket to clear, as they are considerably larger than a standard M10 nut.
 Instead you could try cutting through one side of a standard nut, fitting it into a socket and threading that on to the stud to try and clean up the thread.
Title: Re: Down pipe misthread
Post by: Roger777 on 15 March 2011, 20:46:42
take  manifold off drill out old stud retap put a set stud in from top of manifold i did this with three studs on mine do not use gasket seal or bodge it will only come out
Title: Re: Down pipe misthread
Post by: amba on 15 March 2011, 21:02:21
If you can get a stud extractor socket onto the damaged threaded stud you will be able to remove it as the other end with the sound thread is in the manifold.

Remove old stud ..replace with new stud and fit exhaust and do up new copper nut.

Thats no bodge ,infact it is replaceing exactly what you already have without the need to remove the manifold at all.

Irwin stud extractor from Machine Mart.
Title: Re: Down pipe misthread
Post by: JamesV6CDX on 16 March 2011, 14:04:14
Quote
take  manifold off drill out old stud retap put a set stud in from top of manifold i did this with three studs on mine do not use gasket seal or bodge it will only come out

I disagree with this as a first step.

No need for drilling, if you can extract the existing stud - try that first...
Title: Re: Down pipe misthread
Post by: Roger777 on 16 March 2011, 14:30:10
sorry i should have said on mine the stud had sheared  :-?
Title: Re: Down pipe misthread
Post by: omegod on 16 March 2011, 15:00:22
Well thanks for the multiple suggestions :y

On balance I think I will try spacing between the nut and the manifold with other nuts etc and try to get a decent seal then if this is not succesful possibly try using the "threadnut", if I understand this correctly is able to chase a new thread up the stud.

Obviously last resort is to replace the manifold which
i probably can do but would rather not  for obvious reasons. Cheers :y
Title: Re: Down pipe misthread
Post by: ffcgary1 on 16 March 2011, 15:49:06
Omegod, remove the damaged stud wth a stud exractor and replace with new studs. Fit new copper nuts and job done. dont bother with spacing them it might put too much stress on the last part of resonable thread and strip that as well.. with a good extractor they will come out no problem.