Broken Manifold Bolt
 

Now I'm in real trouble. Installing a new manifold gasket, I turned one of the brass nuts to remove and the stud twisted off about an eighth inch inside the block. Never a good thing but I thought I could center punch, drill and extract it. I had no luck with punching and good quality sharp new hard bits bounce off like a rubber ball. I had no idea just how hard a manifold stud could be. I wonder about trying some type of cone shaped tip of stone or steel on a high speed hand motor tool. A guy has a video out there where he welds a shaft on hitting it repeatedly to build up weld. I asked my welder who is very good and highly experienced and he doesn't want to touch it fearing block damage especially with the few threads at the start exposed. Any ideas?

Many thanks,

Greg

Re: Broken Manifold Bolt
 

Drill the stud out,its gonna have to be done. Buy a cobalt tip drill bit. Start small.

Re: Broken Manifold Bolt
 

Buy cobalt drill drills not tipped or coated.

Re: Broken Manifold Bolt
 

I would still try to mig weld a nut over the stud. Weld a flat washer to the stud first then weld a nut to the washer. When done carefully and slowly, the weld will not damage the threads in the cast iron. The heat on the stud will help to free it up. Do not try an "easyout" because if the stud broke off due to being seized in the threads, the "easyout" will probably break off too and then you have a real mess.

Re: Broken Manifold Bolt
 

First I'd use a fine point acetylene torch and heat the stud red, then cool with wet rag. Do this a few times then drill out. Use a very small drill bit first, run drill slowly and make sure its centered. Then progressively use larger bits. I'd use left hand bits, one of them may end up turning out the stud. When done use a tap to clean out the threads. May be time to heat/cool the rest of the studs and replace them all. Be careful to heat the stud, limit the heat on the surrounding cast iron block. The heat/cool treatment will pretty much loosen even the worst offender, just keep at it.

Re: Broken Manifold Bolt
 

When the screw is broken off below the surface, it really limits your options for getting it out and save the threads. ESPECIALLY WHEN THE SCREW HAS BEEN HARDENED BY LOCAL HEAT.
The safest and QUICKEST method is to pull the engine and have a machine shop machine it out with carbide tooling or EDM.
Heating and quenching is the LAST thing you want to do. That will make the screw and area including the block harder.
If it was flush or higher, the welded washer and nut is the best method.

Re: Broken Manifold Bolt
 

Heating and letting the stud cool very slowly will anneal the broken stud and make it softer.


The stud you have is probably high carbon steel or it would not be hard. Heat with a fine tip acetylene torch and when it is red, just back away the torch a little and slowly back the heat down. Let it cool slowly on its own. Do not quench. Two things should happen, the stud should be softer if you have to drill it out and it may also loosen a little.


If the stud was low carbon steel it should be soft because low carbon steel will not get hard on its own with heat. In such a case, you can heat and quench and the broken piece will not get hard, it will stay soft.


I would first try to weld a thick washer to the broken part using a TIG welder and someone who knows what they are doing. Often, with MIG, you really can not get a good weld in these situations.


You will not hurt the threads in the block. Cast Iron melts at a higher temp then steel.


I have removed lots of broken studs using TIG and welding a thick washer to the stud and then a nut to the washer. Not necessary to remove the engine.


Just get some help from someone who knows what they are doing. You do not want to screw up the situation so you have a more difficult problem to solve.


Replace all the studs with good quality studs. Use grads 8 steel nuts and definitely always use anti-sieze on the nuts and also on the muffler clamp bolts and nuts.


My experience,


Chris W.

Re: Broken Manifold Bolt
 

Below surface makes it a drill it out to me
Should not be brass nuts for manifold to block

Re: Broken Manifold Bolt
 

Pete's suggestion is the safest way forward. With the engine out the task is just a little easier and facilitates more effective means. Good Luck.

Re: Broken Manifold Bolt
 

I have some of these and they drill about anything.
https://www.amazon.com/01505-5-Piece...gateway&sr=8-3


Bob

Re: Broken Manifold Bolt
 

Many thanks for all of the varied opinions on this and remembering that I am the one asking for help, will not disagree with any regarding proceedure. I will though comment on the nature of the product which seems apparent and go along with what Chris indicates regarding the high carbon content of these recently installed like new studs. They are harder than hard and brittle, just like iron which is why I believe it twisted off as I was conscious of not applying too much pressure. Manifold studs are commonly drilled out that have been subject to heat for years, but are good low carbon processed steel with a softened flexibility. Why anyone would make/sell studs this hard and brittle is beyond me. A good study here and lesion should be to test hardness and if like these, discard. To add to the opinions, just got a call back from a welder who indicated "TIG by one who really knows it, not me".

Re: Broken Manifold Bolt
 

Kurt, If not brass nuts here, which is what I have always been told is correct, what would you use?
Whether brass or steel, I use a good anti seize on them.

Re: Broken Manifold Bolt
 

Grade 8 steel nuts WITH ANTI-SIEZE.


You definitely need Anti-Sieze Compound on any threaded fastener that sees heat. Also use grade 8 steel hardware with Anti-Sieze on the muffler clamp hardware.


Brass can seize and become difficult to remove.


Chris W.

Re: Broken Manifold Bolt
 

If you provide your location there may be someone nearby that would be willing to give you a hand. With the proper bit that stud "will" allow it to be drilled. Meanwhile are you soaking it in PB Blaster, Krol or 50/50 acetone-auto trans fluid? Chap

Re: Broken Manifold Bolt
 

IF you decide to drill, try to find LEFT hand drills. Start small and move up.
Paul in CT

Re: Broken Manifold Bolt
 

Greg,

My suggestion is to put your general location in your profile. What does this have to do with the problem? In some areas there are companies that specialize in what you are trying to do. I don't mean a machine shop with a set of easy outs. I live in Los Angeles and do to the large number of companies doing machining on high value parts there are companies that have tools and techniques to solve the problem.

Charlie Stephens

Re: Broken Manifold Bolt
 

If you do drill it out to install a helicoil you might want to use a drill guide to help ensure the drill is going in straight. Someone replaced a manifold stud on my Model A and got it crooked and it makes it hard to get the gasket to fit right.

Re: Broken Manifold Bolt
 

Make a drill fixture with a flat plate about 3/4 or 1 inch thick. Use a gasket as a pattern to put in two other holes to hold it in place. This will keep your hand drill square so you don't drill at an angle. Three holes, two to hold it and one the same size as you want the stud drilled to. You could even drill it real small as some have suggested, drill the stud with a small drill. Then open up the fixture to the next size and drill. Be patient.