Broken downpipe stud - ideas?
 

I could smell an exhaust leak on the car, so when I did the engine mounts I pulled the downpipe off at the same time. The top front stud was sheared which should be the culprit. The bottom left stud is stuck in, but I'll try the "two nut" method on that one shortly. I've been spraying them both with penetrating oil for a couple of days before attempting anything as I really want to avoid having to pull the turbos and I believe manifold off. I've never welded/don't have a welder or I was thinking to weld a nut on the broken stud to try and to wrench it off. I do have a small handheld torch I used to loosen a brake line nut which I can maneuver in there.

What steps/methods would experienced members use in my position without welding access? Any other handtools I could buy to avoid making it worse/improve my odds?

Or are the odds so low that should I just bolt the DP back on and take it to a shop with welding equipment to avoid the chances of shearing off the stud completely.



https://cimg5.ibsrv.net/gimg/www.rx7...e2992d5a87.jpg

I had a similar incident years ago. Drenched the studs in some break free the night prior and then used vice grips to break and remove them. Worked for me, but try at your own risk as it will damage the threads and make it that much more difficult to remove by other methods.

Some Knipex pliers might be able to give you enough grip to get it out.

Don't try vice grips - they won't get you anywhere, just will round it out and make a big damn mess.

Try these to start with -


You can sometimes find these setups at local car parts stores. They are designed to remove studs, it fits over the stud and has 3 barrels inside that push on the stud as you go to tighten or loosen. It will grab it as good as it can be grabbed and hopefully pull it out.

Before using the stud remover I would heat it up as much as possible.

If that fails, stop what you are doing and pull the turbos. Take them to a machine shop or the like and have them remove it. If you start dorking around with drills, EZ-Outs, etc. you're just going to make a bigger problem.

The option that works many times is welding a nut to the broken stud - the heat of welding will shock the fastener then you have a nut you can turn. Most likely you don't have a welder but again that is something a shop may be able to help with.

When you put things back together, use copper clad exhaust nuts. The Mazda nuts are way too aggressive and that's why you are in the situation you are in. The copper nuts are much more forgiving and work wonderfully.

Dale

Those studs are in pretty tight. Whatever you try, you should soak it in PB Blaster or similar penetrating oil for a day or two first. I don't know if this type of stud extractor tool will fit in there, but if so, it will grip the broken stud end much better than any pliers:


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In the event the extractors don't work and you want to try one last thing before welding a nut to the stud - I'm going to double down on Knipex pliers lol. They've saved me many times and they are something of a different breed. You can stand on them and kick them and they still won't slip.

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Hard pressed to get a good enough purchase with multi-grips I reckon. Two nut method, it's ok in desperate circumstances I suppose, but the stud extractor is the much better way. I'd suggest trying to work slowly back and forward if it's tight, those inconel studs gall and snap without much warning or provocation.

Success! Sorry, I didn't see all these messages until today. Someone offline recommended something like this and lent them to me: https://www.zoro.com/proto-boltstuds...00/i/G1460593/

I started with the lower one that is intact, 2 nut method and penetrating oil. Came off nice and easy.

I started with a 10mm extractor and locked it on... it started to turn with decent force and I was relieved. Dancing, photographed it. Then I realized it was just turning and found it had stripped the stud. Damn.

Next I heated up the stud with a handheld torch and forced the 8mm on. Prayed, tons of lube and got to work. It wouldn't budge until I hit it with flame again with the extractor on, let it cool for 45 seconds and then went at it. It broke loose and started to creak out. Penetrating oil every turn and it finally came out with a lot of force.

Looking at the stud it looks like it was cross-threaded on install, although I guess the heat could have done this?

Do you guys think a new stud will go in the manifold, or should I use some gasket sealer on the threads when I try? I'm trying to avoid pulling the other stuff off until I'm ready to upgrade to new twins and maybe an efini y-pipe.... I'm not the most mechanically inclined and it's relatively new to me so a simple fix that will hold is ideal.

Thanks for all the help. Appreciated.

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https://cimg4.ibsrv.net/gimg/www.rx7...002093d184.jpg
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Good deal getting the studs out!

On the one that looks like it cross threaded on install, hopefully the threads on the manifold side are undamaged or can be fixed/cleaned up with a tap. I would run a tap (same size/thread pitch as new stud) into the manifold's threaded holes to chase the threads before attempting to put the new stud in there. Then install the stud.

Excellent idea. A thread chaser saved my ass before.

Also this is a great reference on studs for the whole twin setup -

https://www.rx7club.com/3rd-generati.../#post10669635

Dale

Congrats on getting them out.
I second chasing the holes and any studs to be reused. Plenty of hi-temp (copper) anti-seize going back on. And check your gasket closely. I’m told they can be reused...and new ones are expensive. But I was never brave enough and just went new since it’s such a pita spot to work in.

I have sort of a similar problem. One of my DP nuts is slightly backed off causing a similar leak but the stud is totally stripped. Any thoughts?
https://cimg4.ibsrv.net/gimg/www.rx7...6e2dbd8ede.jpg

You will have to cut the nut off, get the downpipe off, then work on getting that bad stud out.

Dale

So leave it until I need new turbos, and deal with it then. Got it. :lol: