Replacing rusted exhaust cylinder head studs

[GADGET]

It seems to me that, with age, it's becoming a problem with the exhaust cylinder head studs (which hold on the header pipes) becoming rusted and impossible to remove from the heads to replace them, either the headers become steadfast, in extreme cases leaving no choice but to cut the headers off, or, in attempting to remove the stud it snaps. Leaving the only remaining choice as attempting the removal of the remaining part of the of the stud.
Maybe its just my bad luck, but I've tried heat, soaking in penetrating oil over weeks, on one of my 1150 heads I stripped it down completely , including removing the valves and soaked it in a bucket of used engine oil for a month, which resulted in one coming out and the other snapping .
Has anyone found a machine shop that does a good job of accurately drilling out the studs and installing an insert? Steve Scriminger, would have been the ideal go to guy a few years ago, but there appears to be a shrinking pool of people in that field. It seems to me that all it needs is for someone with a milling machine and a purpose made jig to bolt the head to and hold it solidly while that pesky stud is drilled out.

 

[Pete.]

I've successfully drilled and tapped them in place on the bike a couple of times now. I don't know that I'd like to do it as a paid job though.

I've also had seriously stuck-in headers which I managed to release after a lot of work with a 4" round rubber mallet.

 

[GADGET]

I've successfully drilled and tapped them in place on the bike a couple of times now. I don't know that I'd like to do it as a paid job though.

I've also had seriously stuck-in headers which I managed to release after a lot of work with a 4" round rubber mallet.

Hi Pete, I recently cut a set of headers off, I just could not shift them and I have recently obtained a small milling machine (off here, not in my possession yet)), which I'm hoping will be useful and then the objective will be to get a jig made up to hold the removed cylinder heads in the right position to hopefully drill the old studs out accurately and then probably helicoil insert with a SS stud.

 

[Swell]

Hi, just had the same issue, read what I posted today. In essence, Spark Erosion is the way forward. I used Southern EDM near Horsham. Expensive at £40/stud but a brilliant job with threads in perfect condition.

 

[Steptoe]

1100 three studs are worse than the 1150 two studs
First thing I did on my 1150 many years ago was fit stainless steel dome nuts filled with nickel paste.

 

[davegs]

The way forward is find an engineering firm with a decent sized arc welder (no a diy air cooled job) clamp the earth clamp on the head and put the electrode firmley on the stud at high current, wait for the stud to get red hot and alow to cool (important!) you will find the stud Wii come out with ease. That’s probably what your spark erosion man does.

 

[Adioz]

Did mine earlier this year, 3 came off one snapped. the exhaust rusts to the stud inside.
took to a motorcycle exhaust shop who tig welded nuts onto the stud and they just wound out, one kept snapping so ended up drilling one out.
Stainless with copperslip refitted, be careful if you drill out as an oil gallery is behind the stud.

 

[Swell]

Anyone know what size nut I need for the studs. I’m out of town at the minute and want to buy some stainless nuts to go with the stainless studs.

 

[Beagood]

Anyone know what size nut I need for the studs. I’m out of town at the minute and want to buy some stainless nuts to go with the stainless studs.

https://www.motorworks.co.uk/exhaust-nut-exa53602-1.html

 

[theoneandonly]

I used Southern EDM near Horsham. Expensive at £40/stud but a brilliant job with threads in perfect condition.

you need a re-adjustment of values , that is NOT expensive.

 

[Swell]

https://www.motorworks.co.uk/exhaust-nut-exa53602-1.html

Says they’re not compatible with the 1150RT.

 

[Comfy Old Boots]

Says they’re not compatible with the 1150RT.

Call Motorworks they will give you the correct one, have your frame number to hand.

 

[Hobowallet]

Good morning, I thought to maybe post here rather than start a new thread.

I am just doing a lot of service work to my 1100 gs and have seen the exhaust bolts are awful, one looks to have corroded to explosion, the other has totally disintegrated. Luckily the lowest bolt on both side is intact.

I am in two minds if I should try to split the remainder of the nuts off first hopefully leaving a good amount of stud that I maybe able to weld a nut on and with copious amounts of heat having a half chance to remove or just cut to the chase, have the studs snap as I expect they will and remove head and get it done professionally..

Is there anyone in Essex that could be recommended for stud removal work?…

 

[Swell]

I tried everything on my 1150RT and had no success. It’s a common problem and when I asked Motorworks for advice they said to find someone who has Spark Erosion (it may be listed as EDM) capability. They said they never touch them on their 2nd hand heads as they always sheer and render the head useless. There’s bound to be someone in Essex providing this service, if not, try Southern EDM near Horsham, top blokes with all the gear. https://www.southernedm.co.uk/contact

 

[Swell]

BTW, some advised that £240 to have studs removed from two heads is not expensive, (see earlier in the thread), whilst I’m very grateful for the excellent service provided and the outstanding result, £240, imo, is not cheap.

 

[Hobowallet]

BTW, some advised that £240 to have studs removed from two heads is not expensive, (see earlier in the thread), whilst I’m very grateful for the excellent service provided and the outstanding result, £240, imo, is not cheap.

Yeah I agree £240 isn’t cheap, esp when you consider the labour in personal time to strip the head.

I am wondering if I can use a impact chisel to break what is left of the nuts, then somehow find a die that will fit over the threads with room to spin..

Such a PITA…

I’m counting on welding a nut and heat as the worst case home fix before I need to send away…

Thanks for the advice

 

[Swell]

I tried tacking a nut on but it just sheered right up against the head, I then tried drilling and taping it but it just wouldn’t budge, it had pretty much fused to the aluminium. I didn’t manage to move one of the six. You may have to remove the head to get the right amount of heat in the right location to get them to move. At least if the heads are off, you’ll save a bit of time when/if you’re unsuccessful.
I can only wish you the best of luck.

 

[john1961]

I tried tacking a nut on but it just sheered right up against the head, I then tried drilling and taping it but it just wouldn’t budge, it had pretty much fused to the aluminium. I didn’t manage to move one of the six. You may have to remove the head to get the right amount of heat in the right location to get them to move. At least if the heads are off, you’ll save a bit of time when/if you’re unsuccessful.
I can only wish you the best of luck.

has anybody used titanium studs for a repair, or just stainless steel, only a thought, on a porsche forum other day and they use them when replacing exhaust manifolds.

 

[Hobowallet]

I tried tacking a nut on but it just sheered right up against the head, I then tried drilling and taping it but it just wouldn’t budge, it had pretty much fused to the aluminium. I didn’t manage to move one of the six. You may have to remove the head to get the right amount of heat in the right location to get them to move. At least if the heads are off, you’ll save a bit of time when/if you’re unsuccessful.
I can only wish you the best of luck.

I have had good outcomes before welding a nut on the stud then applying heat, I cannot recall what gas I used and I think the heat build up from the welding got the stud out.. But that was on a Honda….


If I can crack the nuts off I think only one stud on each head is a total lose. Amazing how the nuts look to be total exploded with corrosion.

I would definitely like to understand if titanium is the way to go…

 

[davegs]

I have had good outcomes before welding a nut on the stud then applying heat, I cannot recall what gas I used and I think the heat build up from the welding got the stud out.. But that was on a Honda….


If I can crack the nuts off I think only one stud on each head is a total lose. Amazing how the nuts look to be total exploded with corrosion.

I would definitely like to understand if titanium is the way to go…

As I’ve said before a good eng firm ca put a arc welder electrode on it and this will heat up the stud to red hot and when it cools take out the stud head needs to come off but safer than trying to heat it with gas as no chance of damaging the head. Cray engineering used to do this in Crayford kent a mates was done like this as good as new.