TIG use case - remove broken bolt in manifold

[Olli]

I might need to extract a broken bolt in an exhaust manifold. To further complicate the situation the remnant of the bolt is recessed. One option is to increase its height by welding cautiously on top of it until it protrudes again and finally weld a nut on top. Can somebody provide settings (current, tungsten diameter) for TIG welding in this case - the bolt is 3/8” .. Or any other tips.
Thanks in advance.

Oliver

 

[mtt.tr]

Not sure id bother, better off getting a machihe shop to remove it


Unless perfectly clean i i reckon your tungsten will be contaminated with in seconds.
And its not too far from flush

 

[123hotchef]

How far in is it

 

[123hotchef]

Left hand drill bit and drill it. Are the bolts not copper

 

[Dcal]

Photo?
Or what's it off and is it an alloy or cast head?

I've had great results doing what you are proposing, just used a 2.4 tungsten but sharpened to a point.
Plenty of amps (I used about 100) to get the heat into the stud. Short hot blasts worked best for me.
Might be worthwhile putting a steel washer over the stud to stop arc strikes on the head but not totally necessary.
I tend to build it up and then weld it to the washer then weld a nut to the washer and screw it out.

Only time it has failed for me, is on hardened 3/16 bolts in the ally head of a B&S lawn mower engine (the bolt broke further down but the broken bit came out.

 

[gordon stephenson]

What about the old fashioned approach, Drill out the broken stud and pick out any remaining threads and retap if necessary?

 

[mtt.tr]

What about the old fashioned approach, Drill out the broken stud and pick out any remaining threads and retap if necessary?

Far too sensible

 

[Dcal]

When all else fails I drill it out and go for the helicoils. (unless it's a hardened bolt that I can't drill out)
Doesn't happen often as the heat from the tig usually frees it up.

Also the heat from from the tig might help take the temper out of the bolt so nothing lost. (it's not going to make it harder)

 

[Olli]

It is part of the project to reseal the engine of my classic car (Pontiac Firebird V8). 2 bolts of the driver side exhaust manifold are torn and missing. From what I’m able to see with a micro USB camera one might be level and one seems to be recessed in the cylinder head when the exhaust manifold is off. However, more will likely to be torn while removing them (also addressed and hopefully minimized by using an induction heater device). I’m considering all options, however, bolt extractors apparently yield mixed results even when using renown brands. Helicoil or Timesert inserts would be the last resort. TIG welding as mentioned above seems to be a good option, provided that you know what to do. Hence, I’m practicing it first on bolts and nuts lying around. No time pressure.

Olli

 

[Turbo]

It is part of the project to reseal the engine of my classic car (Pontiac Firebird V8). 2 bolts of the driver side exhaust manifold are torn and missing. From what I’m able to see with a micro USB camera one might be level and one seems to be recessed in the cylinder head when the exhaust manifold is off. However, more will likely to be torn while removing them (also addressed and hopefully minimized by using an induction heater device). I’m considering all options, however, bolt extractors apparently yield mixed results even when using renown brands. Helicoil or Timesert inserts would be the last resort. TIG welding as mentioned above seems to be a good option, provided that you know what to do. Hence, I’m practicing it first on bolts and nuts lying around. No time pressure.

Olli

You mention bolt extractors, I assume you mean the things with a left hand spiral that you screw into a hole drilled in the bolt? They will only remove the bolt if it's loose, if it's tight don't even try as you will snap off the hardened steel extractor in the hole, then you are in deep trouble!

Depending on the access the tig method outlined by Dcal works very well. I've also used a stick welder which works too but not as easy. Mig is easy but it's hard to get enough heat into the bolt.

 

[Olli]

Yes, I meant the left hand spiral bolt extractor approach. However, regardless of the actually employed method I will use penetration oil starting several days before.

 

[Turbo]

Yes, I meant the left hand spiral bolt extractor approach. However, regardless of the actually employed method I will use penetration oil starting several days before.

The only ones I've used that are remotely useful are the tapered square ones you hammer in.

As for penetrating oil, the best stuff is a 50/50 mix of atf & acetone (or cellulose thinners). I keep it in a lab wash bottle so I can squirt it on the bolt. You need to shake it before use as it separates when standing.

If you can turn the head on its side, make a ring of putty around the stud & make a puddle of penetration fluid around it.

 

[RichardM]

Personally I've not had good results with screw extractors if the bolt has corroded or been Loctited in.
If the head is alloy and with good access I would go for tig first. Build up with weld, put a washer on, weld a nut on top then allow to cool a bit. Spray with penetrating fluid, leave for a bit then undo (hopefully).

 

[Wallace]

I have used the Tig for a couple of broken studs and bolts, being able to apply heat directly to the broken part is particularly useful if corroded in.

 

[Brad93]

If its deep you can only really drill it out with a left hand drill and then hope it rotates out or pick the threads out.

 

[monkeh]

A few blasts with the TIG should heat it up nicely and loosen it up, then try to extract it. If not then try to build it up with the TIG. With a big cup you should be good with a large stickout.

 

[Olli]

I’m thinking of another method, too. A combination of bolt extractor and induction heater in case of a recessed bolt ...
Drill the hole and punch the extractor into the bolt then use the induction heater like this one
https://www.ebay.com/itm/LED-Mini-D...ive-Remover-Flameless-Heat-110V-/312565596834 to transfer heat via the extractor into the bolt. Now try to drill it out.

 

[pod70]

Aren't the heads on a Pontiac V8 cast iron? - the chances are you are just as likely to weld the recessed bolt to the head.

 

[Dcal]

However, more will likely to be torn while removing them (also addressed and hopefully minimized by using an induction heater device).

Before you try removing the remaining nuts, get a die nut and run it up the exposed thread.
They usually slacken but then pick up on the rusted threads and wring off.
The induction heater is a great tool as long as you can get it to where the heat is needed and you want them red hot.
Oxy acetylene is also geat for applying precise heat if you have access to it.

 

[500e]

Scary things stud extractors a world of hurt if they brake,=.
If the head is off drill it out preferably set up on a mill.
As @Brad93 said left hand drill a surprising amount unscrew while drilling.
The strait flute extractors seem to be better than the helical ones a couple of people I know drill then hammer in Posidrive bits they swear it works my feeling is if it breaks you are back to the world of hurt