Truck Shop
Senior Member
Cat makes a guide tool for drilling/removing broken exhaust manifold studs on the 3406-C15.
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Saw a neat trick, on youtube...
- Thread starter DIYDAVE
- Start date
terex herder
Senior Member
3406 studs are about the only studs I have not been able to remove by welding a handle on them. Regardless of the filler I used, it would break at the surface of the stud, and then leave the surface hard as wedding tackle. I then had to grind the hardened face off the stud so it could be drilled. I made my own drilling guide to keep things on center.
For broken screws that just have the head broken off leaving the threads in the hole I first try a pneumatic engraver such as a CP9361 air scribe. Electric engravers are useless here. A air hammer on larger threaded screws often helps loosen the threads up. I took out a M20 in a hoe final drive today with this method, another one to do tomorrow.
For broken screws that just have the head broken off leaving the threads in the hole I first try a pneumatic engraver such as a CP9361 air scribe. Electric engravers are useless here. A air hammer on larger threaded screws often helps loosen the threads up. I took out a M20 in a hoe final drive today with this method, another one to do tomorrow.
JPV
Senior Member
I have successfully removed those thermostat housing bolts on Cat motors by drilling them but may or may not have nicked the housing a time two, I will never tell! I once drilled through the middle of an exhaust manifold bolt on a 6.0 liter Chevrolet aluminum head right into the water jacket, it's a sick feeling when you think the drill broke through the bolt and you pull it out and get coolant pissing. That was with a right angle drill up against the firewall, I then pulled the head to fix it properly.
Flat Thunder Channel
Senior Member
Skeptical of I could make this welding / copper tube trick work. I thought it was worth sharing because I never thought of it before. This guy has some good ideas on occasion.
I had that very same idea a few weeks ago but ended up not attempting it as I was able to get my bolts out with some careful buildup plus I wasn’t sure where I was going to get the copper tubing of the correct diameter (it’s hard to source stuff like that for us with our limited supply sources through the dealer). It is nice to see it was a viable idea should I need to do it in the future.
kshansen
Senior Member
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We had a 3408 in a 769 haul truck that had a couple broken exhaust studs that just plain would not come out with the welding technique. Seems it was run for several months with one broken stud as they did not want to shut down the truck for repairs. So I think the slight exhaust leak helped glue those in good.
I had tried at least three time on one welding on the end and boss finally got guy out from dealer. He tried a couple times with the welding with no luck so I did not feel too bad about my failure.
He then got the guide tool out and the super drill bit and finally managed to drill and tap the threads out. At least it was on the right head and near the center so access was almost as good as if the head was sitting on the bench!
I've heard of this method, from others, before, But frankly, my mig welder needs a new liner, and before I take on that expense, I try all other methods, first. Since I have a bolt buster, if I have any doubts that the bolt will snap off, I tend to heat first, and that gets about 95% of my problem bolts loose, without any other means...
I also use the BB to heat up bracket stock, and bend cheap wrenches, to fit particular jobs. If you have a sadistic side, it can also heat up a steel door knob, from the opposite side, for simply MEAN practical jokes!
BigWrench55
Senior Member
I have never personally tried this but had a number of oldtimers tell me this. Cherry the broken bolt with your torch and then stick a candle to it until it cools. Then the bolt will come out like it was never seized. Any oldtimers on here that can confirm this theory?
terex herder
Senior Member
I've tried the candle trick. I was not impressed. The wax is just another penetrant like Kroil or PB Blaster.
I've tried it, mostly works, at least on the smaller diameter bolts. Beeswax seems to work best, apply as the bolt is cooling down from about 250 degrees F, otherwise its too hot...
petepilot
Senior Member
that does work but you must let the bolt cool some otherwise it burns the wax to quickly
Tugger2
Senior Member
Someone got to the top studs on this 3406 with a drill and no guide. I was able to weld the bottom ones out first crack. The drilled one is almost a full hole off ,beyond helicoil . Any ideas? 
terex herder
Senior Member
Glad your welding worked better than mine. What did you use for filler?
With that off center drilled hole you still have to get the broken stud out. If you can get it out with the remaining threads still good I would be temped to put a new stud in the hole and pound a piece of steel in where the miscreant driller took out the extra cast iron. Test it with a nut and spacer before reinstalling the manifold. Otherwise you will have to make a drill guide and use something like a Keensert.
With that off center drilled hole you still have to get the broken stud out. If you can get it out with the remaining threads still good I would be temped to put a new stud in the hole and pound a piece of steel in where the miscreant driller took out the extra cast iron. Test it with a nut and spacer before reinstalling the manifold. Otherwise you will have to make a drill guide and use something like a Keensert.
Tugger2
Senior Member
I have always done them with 3/32" 7018 . Use the next size down flat washer first , then the next size up nut . Give them a sharp wack with a hammer and out they come. I did get the broken remains out of the top hole. Theres 1/2 the original thread left ,i can screw a stud into it. Comes down to replace the head or try plastering it up with something like Belzona.
On something this bad I'd consider the copper pipe trick, get the original stud out, then an end mill, in a milling machine, ream the threads out, then another bigger end mill, till you reach a size that produces a round hole, which can be threaded. Then a custom thread insert. The problem is is there enough meat around the hole to allow this? With all the set-up time (machinist's time aint free, you know!), it just may be cheaper to bite the bullet, and get the new head!
Tinkerer
Senior Member
Can whats left of the original hole be drilled deeper and threaded for a longer stud or bolt ?
Plus the Belzona or Devcon for insurance.
I wouldn't think it would need much more depth to make a permanent repair.
I would guess a little more than the diameter of the stud.
Plus the Belzona or Devcon for insurance.
I wouldn't think it would need much more depth to make a permanent repair.
I would guess a little more than the diameter of the stud.
Tugger2
Senior Member
Im not sure how far in i could go with a deeper stud before comprimizing the head . If it comes down to a real repair ill pull the head off and bore it out on my milling machine.
Mike L
Senior Member
Maybe I missed the post but I didn’t see anyone mention the mini right angle die grinder. Looks like a dentist drill. I drill the broken bolt as large as I can without hitting the threads and then use the grinder to cut 3-4 grooves as close to the threads as I can and knock out the pieces with a tiny punch or screwdriver. I also use many of the methods that you guys do but I like to have as many tools in my arsenal as I can. I may be weird but I almost enjoy removing broken bolts. Nothing like a good challenge!
Me too, Mike, challenge keeps the brain sharp! Since I got the bolt buster, though, that's my first Go to, on the list. Like doin the spline-type EZ outs, but they just take too much time, compared to the BB...
Sberry
Senior Member
A trick is to take a lock washer, tweak it so its flat and won't grab and weld it on first, then other washer or nut. The admix from the slightly harder washer gives it s bit more twist power.