True Confessions (broken exhaust bolt)

[Allie]

There's always one trouble maker in any bunch, and it -will- be the one next to the frame.



I still managed to break it after repeated heatings and soakings. I think after a while the bolt really DOES soften up, and it can fool you into thinking it's starting to move.

I've been doing a lot of heating and soaking since I broke it too, and being careful not to kill the slot I cut in it - cause once that goes there's no way I'm drilling around the frame tube.

My main question is in regards to applying heat. I don't know much about it, except what I've read. I don't know 'how much' heat to really apply with a propane torch. I've been going really slow on it with about the lowest heat I can make without the torch sputtering out. Just before though I think I got an idea of the kind of heat it takes to break threads loose, when I took the heat shield screws out of the mufflers. They were probably in worse shape than the exhaust bolt if appearances can be trusted. Not being constrained by worries of warping a delicate aluminum head, I whacked them with a good sized flame from the torch (after some soaking) and WOW it was like magic - they came right out!

I've done a LOT of reading in the forums, but I still don't have a clear idea of how much I can hit the exhaust bolt with and not do damage to the head. Would someone please spell it out for 'Dummies'? I do also have a can of compressed gas that I haven't tried on the bolt yet, it's for dusting electronics. I know the CAN sure gets frosty in a hurry, will that stuff cool the bolt as described in the posts I read?

Thanks muchas muchly, all of you, for your help!

Allie

[Allie]

By the way looking at that slot in the bolt, It doesn't look like it's in the same position as when I cut it. There's no way I could have cut it straight up and down like that. I thought I felt it move at one point, but then thought my mind was playing tricks on me. It does that some times. It could have something to do with the heat I was using at the time.

[Rein]

You can use the compressed air can. Turn it upside down and it practically shoots snow.

Heat the bolt still it's cherry red, then hit it with the can. Otherwise, stick to heating the area around the bolt, not the bolt itself.

[blowerbike]

if you knew a welder that had a portable set up.
he could weld a nut over the stub you have left.
a lot of times the heat from the welding and having a new nut to put your socket on will remove it.
other times on bolts that haven't been removed in a LONG TIME.
removal of the head is needed so a machine shop can remove/machine the broken bolt with an end mill.
i usually run a bike and get it really hot before trying to remove exhaust bolts(when the bike is runnable).
this works 9 out of 10 times.
didn't work a few days ago... broke 2 off of a parts bike

[simon kuether]

Why don't you unbolt your engine and turn it so you can get at it ?
Goodluck .

Cheers , Simon .

[almarconi]

if you knew a welder that had a portable set up.
he could weld a nut over the stub you have left.
a lot of times the heat from the welding and having a new nut to put your socket on will remove it.

Excellent suggestion for getting broken bolts out, I've done this several times on stubborn bolts. I put a washer over the stub, stick a nut on top and fill the center with the welder.

[Flyboy]

Hi Al
At the risk of stating the obvious here, you want to be concentrating your heat on the head itself, not the bolt, the idea is for the head to heat up and expand away from the bolt, while the bolt remains relativly cool.
You can apply a fair bit of heat to the head without damamge, but keeping the heat on too long will give it time to soak from the head into the bolt which will obviously then expand as well, back to square one.
Just play your flame around the head about an inch or two away from the bolt for about two or three minutes then hit the bolt with the screwdriver, it should come straight out.
Good luck.

[Allie]

Nothing is too obvious for me at the moment, I mean I know not to stick the torch in my eye but you know. I did play with it with a good medium flame earlier, walking the flame around the bolt like that, no luck. I probably heated it too long though. That head sure does disperse heat in a jiffy - it sounds like maybe I should crank the flame up good and strong and heat it quick. I have yet to try the air, but it's coming. If I can find someone with a welder I will see about having them come out. If it comes to it unbolting the engine could be done too. Lots of good suggestions, as always!

[Flyboy]

Damn, don't you sleep Al, must be stupid o'clock in the morning there?
Don't loose sleep over it, you will get wrinkles before your time.

[Nessism]

I'd heat the bolt good and hot, red hot. The idea is to break down the chemical bond holding it in place. Turn the screw both directions until it starts to move, then hit it with more PB Blaster and turn it back and forth until it moves some more. Work slow, don't force things and hopefully it will come out.

[blowerbike]

its in the worse place possible..
can't get to it very well.
propane torch is not going to get it.
the broken bolt is now part of the aluminum.
the aluminum needs to be near molten to have a chance and thats with a straight shot at the bolt.
not trying to be a debbie downer but a person has to get very serious with this.
anything short of acetylene/oxygen torches or the welded nut trick i mentioned is just treading water.
sorry for the bad news.

[Skateguy50]

May I ask why are you taking the exhaust off? I thought you where making progress with the smaller shim.

If it is to do get the head off anyways, dont fight the bolt on the bike. If you just wanted to put new exhaust gaskets on... then go for that. but man that is my greatest fear... I hate broken bolts.

I would agree though, if you could have turned it with heat you would have already. Try to make a friend with someone who can weld and has a portable welder.

[Griffin]

I just broke off TWO exhaust bolts on my 850g project bike (the exhaust had never been off, I think. In fact, I'm not sure if the valve cover had ever been off either). One of them was the same bolt you broke (#3 cylinder, lower bolt by the frame).

I successfully drilled out the bolts (using three different sized drill bits, starting small and working my way to the proper sized hole) and then tapped both holes with a taper, then plug, then bottoming tap. It took me about four hours to do both holes, and was pretty dicey work. But now, both holes are good as new with no worries.

[blowerbike]

I just broke off TWO exhaust bolts on my 850g project bike (the exhaust had never been off, I think. In fact, I'm not sure if the valve cover had ever been off either). One of them was the same bolt you broke (#3 cylinder, lower bolt by the frame).

I successfully drilled out the bolts (using three different sized drill bits, starting small and working my way to the proper sized hole) and then tapped both holes with a taper, then plug, then bottoming tap. It took me about four hours to do both holes, and was pretty dicey work. But now, both holes are good as new with no worries.

can i barrow your horse shoe for the weekend?

[Allie]

Well the pipes already ARE off. I took them off to listen at the exhaust ports for escaping air, as described in the backfiring thread. I ended up with one broken bolt out of the deal.

I agree that there's a good chance that propane won't cut it, but it would be rather silly of my not to at least try it. I disagree with the assessment that I would already have moved it if it were going to move because I don't think I've used enough heat yet. I'm thinking the next step is to heat the bold red hot, then spray some snow on it and see if it breaks the bond, and go from there. From other reading it sounds as if that will put some temper back into the bolt?