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Exhaust studs removal - I hope you don't end up here....

Posted: 24 Jul 2006, 08:49
by sonic23
I've been working on a 2.1 DJ WBX at the weekend. I'd been soaking the studs all week. 6 came out ok. The other two just won't budge.

They're the top two, nearside and offside facing the gearbox and they were bolts rather than studs which were totally siezed, so had to cut the heads off.

Next I tried to mole grip what was left.....This ended up sheering the bolt..
Next I cut a slot into what was remaining with a dremmel. I then put an impact driver into the slot and after a few solid taps the bit for the impact driver fractured, along with some more metal shearing off the stud/bolt

There's not much left to work with now - so I guess I've got to try and drill them out.......unless anyone's got any bright ideas????

Image

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Rich

re: Exhaust studs removal - I hope you don't end up here....

Posted: 24 Jul 2006, 11:00
by Grun
sonic23,
You probably don't need to, but this link to the wiki may be worth a read before getting the drill out.
Look Here

Good luck

Mike (I be in Devon) :D

Posted: 24 Jul 2006, 15:19
by CovKid
To comment would be worse than when lost, meeting the yokel who says "Ah, you don't want to start from 'ere".

I think we ALL feel your pain here. Yep, drilling out probably your only option. Make sure you use a drill bit thats man (or woman) enough to deal with the job though - not one you found in Uncle Sids toolbox.....

I might add, I have occasionally removed them by using a hammer and punch in the right place to 'unscrew' the stud but clearly if its THAT stubborn your best bet is to use a good dot punch first to establish the centre and increase the drill size gradually. Try a stud extractor when theres enough to bite on, if not, drill and retap. Easier with engine out but thats stating the obvious. If they were bolts as you say, good chance the metal they were made of was el-crappo meaning they don't respond that well to forced removal. Sadly I've seen Quick-Fit do this kind of thing. Good studs are made of infinately better material so you should find drilling isn't too bad - providing you have enough room to put the drill square to the thing. You may find that the extra 20 mins needed to remove the engine could save you a lot of cursing as the job progresses - way easier to drill in squarely with engine out.

Posted: 24 Jul 2006, 17:29
by Kermit
Another possible option that sometimes works is to place a new nut over what is left then pool weld it, by this I mean weld the remaining stud to the nut.

This will do two things, it will get the area hot and maybe crack where its seized and gives you someting get hold off.

If this fails then drill and re-tap

Kerr

Posted: 25 Jul 2006, 07:08
by Don-Tucker
To me there is only one way to go now,and Ive done it a few times believe me,I would centre pop as near to the centre as you can,drill a 3mm hole first then tapping size and finally retap.The thing is to get as near the centre as possible with the first drill.
Best of luck Don

Posted: 25 Jul 2006, 07:25
by guz
easiest yet....

drop the head off at an engineering place
and get them to do it, my local place
usually charge a fiver a stud to remove
and replace the bloody things.

Posted: 25 Jul 2006, 07:53
by CovKid
I doubt you'll get better answers than those we've given you Rich. I think we'd all agree its a headache scenario. Last comment about having these removed by an engineering shop is a good one. What you DON'T want to do is damage the head. Its a different metal to the stud and a lot more costly to replace. He does have a point.

Its sods law that whoever fitted bolts may well have tightened them up hard into the head which is why its being such a pig to remove.

Posted: 25 Jul 2006, 08:44
by sonic23
Thanks to all for the comments.
I was going to try and get away with not dropping the engine out......Given the current run of luck, If I tried to take a head off I reckon the head studs would decide it's their turn to give agro.... :(

Posted: 25 Jul 2006, 09:25
by HarryMann
If you drill them out accurately and then pick them out as described in the Wiki you shouldn't even have to retap them... one at least will need flatting off a bit first to find its centre with a centre pop. start with a 3mm/ 1/8" or thereabouts. See this thread too:

http://www.club80-90.co.uk/forum/viewto ... sc&start=0

.. and choose your weapons carefully.

Its corrosion not tightness that's the problem, there's no tightness now with its head off!

Posted: 25 Jul 2006, 11:13
by SteveW
I have just done 6 bolts or studs all 8mm on a replacement DG engine not all exhaust fixings some are water pipe fixings. on the first one I started with a 3mm bit after about 15mm the bit snapped (not a cheap drill bit either) Had a hell of a job getting it out. so on all the others I went straight in with a 5mm bit then 8.3mm and tapped in helicoils (Recoil brand) not a bad price £25 for a set of tools including 10 inserts. I am going to use new German studs and stainless nuts, washers and lock washers all bolts will be stainless to. I will also use copperslip on reassembly.

Posted: 25 Jul 2006, 11:53
by HarryMann
3.2mm is a good size these days, its just a thou clearance on an 1/8" and a good clearance on a 3mm bolt or screw (8 thou)

You can buy packs of cobalt bits or titanium coated bits quite cheap now from the online suppliers (Screwfix, Axminster etc). Buy at least 5 of the smaller ones.

Also look for 'extension' bits, extra long ones, always worth having one or two of those in various sizes to get the chuck away from the job... once it gets hot, just put some spit on the tip of the bit to keep it cutting and remove swarf at regular intervals to keep it cutting. Keep checking it is dead parallel. Don't try to drill it in one go, stop, spit on it, clear the swarf and take a good gander, re-adjust your angle. If swarf is coming out the hole, however slowly you're making progress, if the drill is blunt, then it means more pressure is needed and likely to snap. Using a smaller battery drill, like a drill/winder at slower speed can help access and accuracy. They tend to have better self-locking chucks too, a lot of which are crap at gripping small drills.

Useful imperial number sizes are No. 30 (1/8" clearance); No. 10 and No. 41, if you find any.