What the hell are the exhaust manifold to downpipe studs on a V8 RRC (1990) made from????

Managed to snap a stud in the exhaust manifold to downpipe last week.

It is resisting every attempt to drill it out. Short of buying Dormer drills what can I do?

I don't seem to be able to reach the NG from my newserver so I'd appreciate it if you could send any answers to:

r j s n i l d r a m c o u k

(No spaces)

many thanks

Richard

Reply to
Richard
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Mailserver access restored now, so I will see any replies (please!)

I'm going to buy some split-tip Cobalt-coated Dormer drills today in the hope that they can get through the stud. Apparently they can penetrate stainless steel.

But, any suggestions and expressions of sympathy will be gratefully received. I was going to replace the other two studs with new ones but I think caution is the better part of valour. Can anyone tell me what thread the original studs would have had? The skirted nuts for the new studs - supplied by RR last week - do not fit the old studs. I removed what appear to be rather tired brass nuts from the old studs.

Richard

Reply to
Richard

The studs should be ERR551. Up to VIN ...FA999999 the nut should be NH108041L with spring washer WA108001L, changing to NTC1966 (nut) and WA108051L (spring washer) from ...GA000001.

NH108041L is a hex M8 nut, NTC1966 is an M8 flange nut.

Cheers Richard

Reply to
beamendsltd

On or around Wed, 20 Aug 2008 22:10:55 +0100, Richard enlightened us thusly:

your biggest problem is that the manifold is softer than the stud, so make sure you drill nicely down the middle - it's possible for the drill to wander off into the CI.

I'd start with about a 5mm. Unfortunately, there's no credibly-reliable way of doing this job with the manifold on the motor.

In the past I've made hybrid studs: 10mm thread on the bit that screws into the manifold and 8mm on the bit for the nut... this was one where the (blind) tapped hole was buggered. If they go through a flange and there's some hope of getting a spanner to the top, the a bolt is the answer.

It's worth hunting some brass nuts for it. In the old days, when they did engineering properly, exhaust manifold nuts were brass, so they didn't stick to the steel thread. Proper brass nuts should be deeper than normal steel nuts, so you can still apply enough torque. Beware of brass-plated steel nuts, I doubt they do the same job!]

Reply to
Austin Shackles

The skirted nuts you were supplied with are M10 which are for later models.

The nuts you want are all the same up until 1992 which are 5/16" U.N.F

NH605041L - Brass nut 5/16" U.N.F

252623 - Manifold stud 5/16" U.N.F x 1.1/2"

I still have them in stock if you can't obtain any local to you.

If you drill a 3mm pilot hole down the middle of the broken stud first and then open it out gradually it should then be easy to remove it without damage to the manifold. Take off the manifold first then if you make a mess of the hole you can always get it helicoiled or tap it out and make and fit a two diameter stud. You could even tap out to M10 and fit one later type stud but you will then have to drill out the corresponding hole in the pipe flange, not really a good idea.

Martin

Reply to
Oily

The V8 studs should be copper/brassy type stuff, with steel nuts - same thing, other way round!

Cheers Richard

Reply to
beamendsltd

Those are for Carb manifolds, not Efi.

Cheers Richard

Reply to
beamendsltd

Thanks to all.

I'm reluctant to remove the manifold - visions of stripping/breaking manifold to head bolts are swirling before my eyes. I have removed the downpipe which now gives me clear - albeit back breaking - access to the underside of the manifold.

The skirted nuts supplied with the new studs do not fit the existing studs. I could attempt to run an M8 die up the remaing studs.

The stud is definately harder than the manifold and made from a lovely silver metal! Possibly titanium!!!! Two of the nuts on the studs were brass - one deep and one shallow. I suspect that the third - on the broken stud - was steel. I have managed to push a 2mm hole through the rems of the stud - which is only the thickness of the manifold flange - and have enlarged it part way through to between 3 and 4 mm.

Martin, even though Richard points out that the brass nuts are for carb studs and I have an EFi I might take you up on your offer. Based on the evidence of the two brass nuts that I removed it's not impossible that someone fitted carb studs? ISTR that you are near Westerham or have I got that seriously wrong?? I'm in Otford.

Cheers

Richard

P.S. I now have a wallet damaging selection of cobalt split-tip drills.

Episode 15 of the saga to follow presently.

R
Reply to
Richard

You're right, I stand corrected. So are they 10mm or 8mm? According to my lists they should be 10mm........... if they are 5/16" UNF then maybe he's got the wrong manifolds fitted, or someone's took the carbs off and fitted the EFI manifold etc.?

Martin

Reply to
Oily

I've got the deep brass nuts 5/16" UNF if you want some I can post them, and a UNF stud to replace the broken one if you get it out. I am just east of Manchester.

Martin

Reply to
Oily

Let's know how they work, in the past I've given up with drills and used a tungsten carbide burr to get a stud out of an ali head in situ and then helicoiled it (nissan maxima freeby).

My 110 V8 has 5 studs and a jubilee holding the pipe on.

AJH

Reply to
AJH

They are bolts in to the head and they may pull out some alloy. My tip is undo all at the same time.. couple of turns each otherwise you put too much stress / angle as it comes slack.

I've also managed to retap the thread on the block so it's not impossible in situ.. and that was with a load of LPG clutter in the way too. I actually chewed the thread replacing the bolt as again when replacing the manifold they should all be tightened a bit at a time and not one at a time.....leaving one to chew up the thread last IYSWIM.

Follow this advice and you should be fine (fingers crossed and buy a charm from a Gypsie and also seek out a black cat to cross your path first mind... ) ;-)

Lee D

Reply to
Lee_D

Thanks Martin

I wonder where I got Westerham from? Thinking of some other RR-wrangler no doubt.

Thank you for the offer of the brass nuts. If you can drop me an email with your address to 'rjs nildram co uk' I will send you an envelope plus ?beer tokens ?proper money.

When I get the broken stud out I will replace it with a plain bolt - no more messing with studs.

Cheers

Richard

Reply to
Richard

The M8 skirted nuts that came with the new studs from RR are just too tight to fir onto the remaining studs - there is that 'yes it fits, oh no it's too tight feeling'. That is why I'm thinking that running an M8 die up the studs - if I can manage to do so - might be a good idea and will reveal the studs as being M8 after all but a bit knocked about. I am wondering if the brass nuts are missleading. Will a 5/16" UNF nut fit (albeit badly) on an M8 stud?

thanks

Richard

Reply to
Richard

Indeed I will.

In one of my blacker moments in this saga I seriously thought that making a small 'C' or 'G' cramp out of a chunk of steel and clamping this around the flanges in place of the broken stud was the easiest option.

It may come to that yet!

Or even clamping plus welding followed by a 'For Sale' sign ;-)

Richard

Reply to
Richard

They should be M8 (that's the 8 in HN108041), but it's highly likely they have be replaced already - M10 would be the logical next size up I suppose. The manifolds/down pipes are interchangable as a pair, so a swap having occurred is quite possible.

Cheers Richard

Reply to
beamendsltd

I've just tried one {*} - it doesn't fit (too tight after a few turns), but I can well imagine someone who's struggling to fit one in situ just wanging it on, as with a spanner it would be possible to make it go on!

The later flange nuts are "self-locking" (NOT nylock!), so they will go on about 3/4 of the nut and then get tight. The last few threads in the nut are deformed slightly to give the self-locking effect (like the NVxxxxxx nuts used on some panhard rod bolts).

If you have a die to hand, trying it will at least let you know what's fitted - theres no saying someone hasn't fitted an imperial stud!

Cheers Richard

{*} Yes, it's a bit quiet today!

Reply to
beamendsltd

I would still suggest removing the manifold from the head, then you could actually see the threads and what they are, that's assuming you've removed the other two nuts. It's not a good idea to just bung on the brass nuts and hope they are right. I will certainly send you the 5/16" UNF nuts if you do require them and you are certain they are the right ones.

Martin

Reply to
Oily

Is it broken off flush, or sticking out a bit? If so, you could try welding a bar to it (assumimg its a steel stud) - this has a double effect if heating it to free it and giving better puchase. The weld won't stick to the cast manifold very well (except, of course, when you don't want it to) - BUT... there is a possibility of cracking the manifold, so last resort time only!

Doing it in situ could be a bit of a challenge........

Cheers Richard

Reply to
beamendsltd

Which combination have you tried Richard?

My 'new' skirted nuts spin freely onto the 'new' studs but grab after that initial turn onto the existing studs.

Richard

Reply to
Richard

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