seized/extraction advice

Just looking for opinions on what course I should take here.

1) I'm still working on swapping a head-gasket after an overheat. (head was slightly warped, has been repaired). (ALH engine).

2) When I was removing the EGR cooler from the turbo/exhaust fitting, one of the M8-torx bolts refused to come out and sheared. Since I couldn't get clearance to drill it, I had to pull the turbo. One of the exhaust-flange studs ALSO sheared. FML.

3) I was able to drill-out the EGR M8-torx bolt satisfactorily, once I got the turbo onto my workbench. Next to the cylinder head.

4) When I tried to remove the exhaust flange stud that broke off, the exhaust flange threads were damaged (I didn't drill perfectly straight). This turbo charger is a Garrett 17, not the normal stock 15. (probably doesn't make any difference here).


I can get a new M8 stud screwed back down in the hole, and the bottom 3 or so turns, it snugs down. But if I turn it about 3 turns, it wiggles. If I turn it another turn, I can just pull the stud right out of the hole. So, the top 7-8 threads or so are stripped, on one side of the hole. I tried cleaning them up with a tap, but it was no good.

So my options, as I see them:

A) I could just snug down the stud as it is, and it will probably hold.

B) I could drill-out the hole to the next size-up (M9), and thread it, and use a step-down stud like this: https://www.ebay.com/itm/SPECIAL-M9...914-T25-Late-Bay-Van-/380784727764?rmvSB=true ...

C) ... or I could drill it and use a helicoil, but will that work here with such a high-temp area? (I'm not sure - I've actually never had to resort to a helicoil before, never had to use one, I've always had good luck extracting broken bolts before now).

Advice?

Helicoil. The head will not get past the coolant temps. If you’re worried about them backing out, you can use tap and slam. Helicoil insert that has a toothed area at the end of the threads on the outside that you put a tool into and tap with a hammer; it deformed the toothed area and makes it permanent. I have no idea what they are actually called. I know you can get them for spark plug thread repair; they are designed for high temp cycle areas. I have use it twice on spark plug repairs, one of them, the coil came out with the spark plug but it worked great and took a bit of force to take the spark plug the brake free, so I suppose it was no fault of the product, and just a stuck spark plug after 90K miles. I used a drop of red lock tight when I did it a 2nd time and I also found out you need to tap the thread deformer harder than you think to make sure it deforms properly. Have not tried to take out the one with red lock tight as it was 10K ago on a car I sold! My feelings on the product is that it’s a great product that you need to use properly if you plan on taking the part back out. Maybe use a tiny bit of copper antisieze on the stud to keep the iron from rusting to the threads of the helicoil. Either way it will be the best solution short of having it drilled out and welded. You can always use alumoly or steel in a stick but that’s very ghetto and the alumaloy is hard to get into a hole like that.

Timesert is the brand I use, they are fantastic.

Timesert
definitely bookmarking this one. definitely better than anything i have used by the description. I want to go strip out a part just so i can try it now!

Sorry if I wasn't clear:

The stud that broke off, broke off in the turbocharger. So the threads aren't in aluminum, it's in that cast-iron-like material that bolts onto the exhaust downpipe that goes right into the catalytic converter.

Still timesert?

OH, thats simple, just tap it out to the next size up after you drill it out. Seeing as its on in the head and on a part that is not critical as the head is, i would keep it simple and cheep.

I ended up going to my local hardware store to look for an M9x1.25 tap, and they didn't have one. But they did have M8x1.25 helicoils.

The helicoil kit called for a 21/64" drill, and not having that I used my Q bit from my indexed set, which is .332", (and 21/64" is .3281", and that ended up being close enough). I've never used these before, so I didn't really get how they worked, but the stud went in quite firmly (and I used some red loctite), so I think I'll trust it.

Probably a bit late to put this out there, but... I"d have just dropped off the turbo/exhaust to a local NAPA/machine shop and had it dealt with. The time one spends messing around is likely going to end up being a lot more (in money and time) than having a shop take care of it: exception would be if you already had all the tools (which it appears the OP did not).

when i get a tap and a drill bit to match i always tape them together with black electrical tape. never EVER buy a tap and die set, only buy the ones you need, when you need them. You will save $100's

yea a part like that will do just fine the way you fixed it. not 100% ideal but not a bad job. will do the trick for sure. glad you got it solved. Cheers