Exhaust header nuts - big problems

[BlueK11LT]

In readiness for my upcoming clutch change and spline lube I decided to check in advance if there were going to be any problems with seized or rounded off fasteners ,in particular the centre stand mounting bolts.and exhaust header nuts.The stand bolts were ok and loosened off nicely,but the exhaust header nuts have presented me with a problem ive never came across on any vehicle previously,at least six of them have corroded away so badly that there is no proper hexagon shape left to get a socket to fit onto,and one of the nuts is so bad there is almost nothing left of it at all and mole grips are just slipping off.
Some of the more accessable nuts on the left-most side of the cyl head might be removeable with heat applied or by cutting a thin slot in them with my dremel and small cutting discs and trying to chisel them off hopefully without damaging the studs,but the innermost nuts are so inaccessible I

just cant figure out what iam going to do about them.

Looks like I have no choice but to cut the header pipes and flanges off by angle grinder,then somehow try to get the remains of the innermost nuts off without damaging the studs,iam just hoping I don't have to remove the cyl. head to get the job done,

I have sourced a replacement exhaust online in very good condition,it is much better than the one already on the bike which has lots of thick rust on its underside so I wont be to unhappy about having to cut it up.
Here are are a few photos of the remains of the header nuts

[Enfield]

I had the same problem - but had luck with a wisegrip - removing all the studs with nuts. Maybe I was lucky none of Them broke.
Regards
Chr


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[TX brick]

You don't have to remove the header to do a spline lube on a K75.

[Laitch]

I have sourced a replacement exhaust online in very good condition,it is much better than the one already on the bike which has lots of thick rust on its underside so I wont be to unhappy about having to cut it up.

You don't have to remove the header to do a spline lube on a K75.

As TX has stated, you can do the lubing without the removing.

You'll need to remove the studs from the head if you grind them down to remove the exhaust pipe assembly. You'll need heat, penetrant, luck, and patience for that job so get your mind ready for it now. Don't grind those studs shorter than necessary so you might have a chance of turning them out of the head instead of needing to drill and tap new holes for the replacements.

[alexg]

As TX has stated, you can do the lubing without the removing.

You'll need to remove the studs from the head if you grind them down to remove the exhaust pipe assembly. You'll need heat, penetrant, luck, and patience for that job so get your mind ready for it now. Don't grind those studs shorter than necessary so you might have a chance of turning them out of the head instead of needing to drill and tap new holes for the replacements.

Use a small cutoff disk with a Dremel tool, and cut the nuts lengthwise or at an angle. Then use a small screwdriver or chisel to open the split nut, and it should come out. Did the same on many headers.


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[The Mighty Gryphon]

You might want to look at these.  A reverse flute cuts into the nut so the harder you turn the harder it grips.

https://www.walmart.com/ip/AmPro-T46301-0-38-in-Drive-Bolt-Extractor-Socket-Set-Metric-44-9-Piece/817722296

[BlueK11LT]

Just wondering why people are mentioning a K75 in their replies? my bike is a K1100LT which have one piece exhausts.
Mighty Gryphon - I had thought of getting a set of those sockets if it proved neccasery had ,they are sold here in the UK under the Irwin brand name
https://www.zoro.co.uk/shop/hand-tools/stud-extractors-3-8%22-sd/10504635-5-pce-expansion-bolt-grip-set-(394002)/p/ZT1006245X?utm_campaign=pla-Hand+Tools+-+&utm_source=google&utm_medium=shopping-pla&utm_keyword=ZT1006245X&istCompanyId=6aa6787b-063e-4414-802d-129f235df603&istItemId=wtqitpttax&istBid=tztx&gclid=Cj0KCQjw2pXXBRD5ARIsAIYoEbdqakprmZMsdXWoVUUJnBAzn3v4ZWf7D-sfwzHowta0p1iwp4zKdPgaAufwEALw_wcB
alexg - after cutting off the headers just below the studs and just before where they join the silencer to get good access I did use the exact method that you mention,firstly cutting away the flanges with a cutting disc on my electric drill,then my dremel with small cutting discs on the nuts then a chisel.
Of the six nuts that were corroded beyond conventional removal I have managed to remove four before calling it a day,hopefully the remaining two should come off without too much bother.
The tricky part is when using the dremel and trying not to cut into the studs themselves,i have damaged a couple of the studs but iam hoping that running a die nut over the studs will restore the threads enough to be useable again.

[The Mighty Gryphon]

Remove the studs and bin them.  You should be able to get stainless replacements at an industrial supply for a less than the cost of the BMW parts which aren't that expensive either.  Add stainless nuts and lock washers with a dollop of copper grease and you'll be good for as long as you wish to own that bike.  It's one of the best places I can think of for stainless hardware.

And you will earn some good Karma for not leaving a corroded mess for the next owner.

Just remember to heat things up with a torch before attempting to remove them.  it will make things a bit easier.  I'm surprised that several haven't come out already.

[BlueK11LT]

Remove the studs and bin them.  You should be able to get stainless replacements at an industrial supply for a less than the cost of the BMW parts which aren't that expensive either.  Add stainless nuts and lock washers with a dollop of copper grease and you'll be good for as long as you wish to own that bike.  It's one of the best places I can think of for stainless hardware.

And you will earn some good Karma for not leaving a corroded mess for the next owner.

Just remember to heat things up with a torch before attempting to remove them.  it will make things a bit easier.  I'm surprised that several haven't come out already.

I was planning to use stainless nuts and spring washers when fitting the new exhaust and ideally I would like to remove the studs and replace them with high tensile stainless studding ( incidentally I work for an industrial supply company and can get all the stuff for pennies)
I will have a go at removing the studding but if they are seized so badly that they are more likely to snap off flush with the cyl head I will just go no further and try to clean and restore the threads as best as possible

[Chri5]

+1 on the nut extractors

 i got the irwin set for the same job after a day of tom di*kery with a blow touch and manual impact wrench, used the irwins and the nuts didnt come off the studs, the stud just came straight out as MG said add heat and you will be golden i would also recommend plus gas penetrant super fast

note that pack is the expansion pack for the irwin so odd sizes you can get the base pack from tool station in the UK

[BlueK11LT]

I managed to get the remains of all the nuts off the studs and clean the threads up with a die nut so that replacement nuts will go on easily,but because of the corrosion the threads have suffered and the gouging caused by the cutting disc any replacement nuts are not going to get as much grip when tightening as they would on brand new studs so iam reluctant to leave the studs in place,so my job for the weekend is using a blow lamp to heat and hopefully extract the studs,but at the first sign that a snapped stud is immenent I will just back off and leave it in place.
I don't think penetrating oil is going to be of much use here,unless it works against gravity it is just going to run down the studs and drip onto the ground

[Martin]

Apparently the best penetrating fluid is a 50-50 mix of ATF and acetone. Do not let it sit on painted surfaces or apply a naked flame to it. Heat up the part and allow it to cool below it's ignition point before applying the fluid. Do it a few times to make sure the fluid has soaked in. Letting it soak for a few days while reapplying the fluid will also help. If you have trouble removing the stud with the double nut method there are self locking stud removers available.
Good luck.

[BlueK11LT]

I got all of the studs out using the double locknut trick,a couple of them did not require any heat,some only required moderate heat with a heat gun,and only a couple were a bit more stubborn and required a blow lamp.
I cut the 8 replacement studs from a length of M8 stainless steel threaded bar,and cut them to about 20cm longer than the originals because when I take the exhaust off to do the clutch I will be replacing the new stainless nuts with much deeper stainless studding connectors for easier access and removal if required in future,i have used these many times on bikes in the past and found them quite usefull.
The photos show the new studs,nuts and the old studs and the remains of the original nuts,and the new studs in place with the threads in the cylinder head cleaned up with a tap and the studs coated with copper grease.


I would certainly recommend that any K bike owners check the header nuts on their bikes,especially if the exhaust has not been removed in a long time,and replace studs and nuts with stainless items.

[Chri5]

 :2thumbup:
1+ on replace the studs asap i had to replace the main rear seal and didnt want to disturb the 4 pipe collecter clamps on my 85 k100 its much easier just to remove the whole exhaust some times

[Scott_]

:2thumbup:
1+ on replace the studs asap i had to replace the main rear seal and didnt want to disturb the 4 pipe collecter clamps on my 85 k100 its much easier just to remove the whole exhaust some times

Unfortunately it's not that easy with the stock 1100 exhaust as it is only 1 single piece. Which I still think was a mistake on BMW's part.

[johnny]

greetings...

now you know why i use nulock nuts on my headers...

j o