Heat exchanger stud

[joe912/62]

I'm in the process of removing my heat exchangers basically because I wanted to remove the catalytic converter to make it easier to do a valve adjustment, my first one on a 911 but did a few on my 912 I once had. As usual I broke a few nuts just flush with the bottom of the thick flange so there are still some threads to work with. How should I proceed, using the 2 nut trick? Here's a photo

[boyt911sc]

Joe,

Buy or borrow an exhaust stud jig to replace broken exhaust stud/s. Without the jig, it would be next to impossible to do a good job. You will regret not using a jig. You have been warned and it is up to you to decide which direction to proceed.

Tony

[Nditiz1]

Double nut can work, also apply heat and lots of it.

You could get the snap on kit or one like it. Torch is your friend.

The snap on kit clamps onto the threads. There is a napa kit to that is a reverse extractor so grips tight when you go to loosen the stud. Again heat heat heat and have some lubricant spray to hopefully get up into the threads.

[john walker's workshop]

Generally, they just shear off flush unless you're really lucky. Then it's jig time and a timesert.

[joe912/62]

Not having much luck using the 2 nut process. I don't want to force it too much.
Was thinking of trying to make a 3d printed jig, don't think it's too complicated.

[Flat6pac]

Stompski Racing makes the jig for broken exhaust studs.
Bruce

[SkunkWorks]

Just went through this for the second time (new 911).

Snapped similar to yours, was able to fit a stud extractor on and it snapped flush at the head. This was with liberal use of a MAP torch so not sure what else I could've done.

Managed to borrow the Stomski jig from a local Pelicanite (thanks Rob!) and somehow none of the drill bits cut into the stud. Tried different bits, drills, pressures, bit profiles, etc.

Was about to give up but google said I should try a masonry bit a try. Success! Had to freehand it as it didn't fit in the Stomski jig so drilled a little bit, reinstalled jig to recenter the hole using the traditional drill bits, removed to use masonry freehand once they stopped cutting. Rinse and repeat. Bit of a faff but got it done in the end.

Highly recommend a jig.

[proporsche]

as the boys said..plus..you should consider remove and switch around the oil return tubes..the small section should be away from the heat exchangers...reason is those 2 o-rings inside will get hard by the heat and leak oil

Ivan

[joe912/62]

Thanks for the tip about the oil return tubes. The problem I'm having is I'm heating the stud red hot but the part of the stud that is within is getting no heat.

[kevbo]

Stomski is the way to go.

[john walker's workshop]

Never heat the stud, just the area in the case or head adjacent to the threads. Still not easy to get exhaust studs out. Jig o rama.

[Nditiz1]

I have the stomski and can loan it out, but I dont believe it works with how much stud is still protruding. Hit me up when you snap it flush.

[SkunkWorks]

Originally Posted by Nditiz1

I have the stomski and can loan it out, but I dont believe it works with how much stud is still protruding. Hit me up when you snap it flush.

I can loan the stud 'extractor' to do exactly that

[kevbo]

You need to have one post to make this work so thankfully you have that. I had 1 that wasn't flush and i was able to use the tool still. It's worth the $$$ because you're on a slippery slope like I was.

[joe912/62]

I tried one last option with a stud puller and snapped the stud.
So decided to 3d print my own jig. Taking inspiration from the Stomaski
Kit this is what I came up with and used successfully.

[joe912/62]

Hardest part is fishing out the little metal pieces.

[Nditiz1]

Way to go Joe! Can you post tour stl files on thingiverse? I'm sure others would really appreciate your hardwork.

[john walker's workshop]

A 17/64 drill bit should leave just the threads which can be removed with a pick and needlenose,

[pkabush]

Originally Posted by SkunkWorks

Just went through this for the second time (new 911).

Snapped similar to yours, was able to fit a stud extractor on and it snapped flush at the head. This was with liberal use of a MAP torch so not sure what else I could've done.

Managed to borrow the Stomski jig from a local Pelicanite (thanks Rob!) and somehow none of the drill bits cut into the stud. Tried different bits, drills, pressures, bit profiles, etc.

Was about to give up but google said I should try a masonry bit a try. Success! Had to freehand it as it didn't fit in the Stomski jig so drilled a little bit, reinstalled jig to recenter the hole using the traditional drill bits, removed to use masonry freehand once they stopped cutting. Rinse and repeat. Bit of a faff but got it done in the end.

Highly recommend a jig.

Are you sure it was a bit specifically designed for masonry? I can’t imagine that working. If so, please post a pic. The usual go to would be a cobalt bit.

[joe912/62]

The only bit I could find