Snapped off and Exhaust Stud - Any Expert Advice

[Tidybuoy]

I should be posting this on the 944 forum but I find it to be a little embarassing that I did something so stupid.

I am replacing my exhaust gaskets as part of a larger project and as the shop manual recommends...I am also replacing the hardware (i.e., exhaust studs).

Everything was going smoothly and I pulled 7 of 8 studs; the 8th came out ok but was much stiffer than the others.

When installing the new studs, the same 8th stud was threading but was doing so with resistance. I had about 3 turns to go & ......SNAP.

I am considering drilling out the stud with some type of guide to keep the drill in the center of the screw - the stud is 1/2 inch into the cylinder head. I'm really hoping to avoid removing the head as I only have 45k miles on the car and it's in good shape (I don't want to jinx that).

Any advice would be great, Ive got a couple of weeks before I tackle this.

My Screwup:


Not too much room (about 6 inches of space):


1/2 Inch of stud snapped off:


Thought of trying somehting like this:

[Superman]

Make a jig, or get a jig (they're out there...at least one Pelicanhead has made them) to hold the drill bit in place. Without the jig, it will be very difficult to keep the bit from slipping sideways and scratching your head/exhaust mating surface. You'll need a right angle drill or attachment. I would suggest getting one or more reverse drill bits (these work in reverse....counterclockwise). Sometimes studs come out just from the drilling....they back out. But only if you are using a reverse drill bit, of course. I like the Snap-On screw extractors. A kit of ten extractors is actually pretty cheap.

Take your time. Relax and do not hurry, do not get angry.

[red-beard]

Re-assemble and sell the car. Tell the new owner that the heavy exhaust sound is from the brand new high flow exhuast...

[A930Rocket]

That QuickCenter might work. Lord knows I could have used it a few times over the years.

With tight access, if you have access to air tools, that might be the way to go with a right angle air drill and short LH drill bits as Sup suggested.

[masraum]

Expert advice?

Yeah, pay an expert to deal with that headache!

I almost thing it would be easier to pull the head and deal with the stud at a comfortable angle.

[Tobra]

I would definitely pull the head for that.

[DanielDudley]

I would start by getting a fine nail set, and use a small hammer to try to spin the stud out by placing the nail set close to the edge of the stud and tapping it with the hammer in the direction you want to go. It isn't seized, and you might get lucky if you have the right access.

Most people would use a tiny cold chisel for this, but a hardened nail set will work.

[gtc]

+1 to pulling the head off...
I used a carbide dremel bit when i snapped an exhaust stud on my 911 and couldn't find a jig. It worked pretty well.

Easy-outs were useless in my case.

[Hugh R]

What is the trade off of pulling the engine versus pulling the head on a 944? I think either way you want a straight shot at that. I've been told to use the largest extractor that you can get in there, you break off a smaller hardened one and you're effed.

[126coupe]

Just make sure the pilot hole is dead bang centered

[island911]

+1 on the carbide dremel bit. It is slow going, but quite do-able.

I've done one with the engine in. --a long time ago, on an Audi 5000. For your 944 it looks like a tough approach. You might want a right-angle Dremel head.

On that "Quick Center" tool .. you may as well just glue down your own bushing/drill-guide. ...But again, you might need a right angle tool/drill.

[sc_rufctr]

Option 1: If you remove the head you could use "nitric acid" to dissolve the stud without dissolving any of the alloy surrounding the stud.

Obviously this would be a good solution if the engine was apart.

Nitric acid to remove broken exhaust studs.

Option 2: Locally there are mobile techs in vans that remove broken hardware. That's all they do.
You call them and they turn up with their special tools and methods...

I'm not sure of the cost but recently someone I know used them and they charged him $120 to remove a broken stud on a Nissan engine. It was the one nearest the firewall.

Also... I'm not sure if this would suit your car but our host sells these high quality head studs for a 911.

[Tidybuoy]

Originally Posted by sc_rufctr

Also... I'm not sure if this would suit your car but our host sells these high quality head studs for a 911.

I thought I had bought "High Quality" as I purchased them from, Pelican and they are listed as Genuine.

Thanks for the tip on the mobile shop. I think I will check with a muffler shop if they know of one of these services. If it's less than $150 it will be cheaper than the tools I'm about to buy.

[lm6y]

The fact that it either bottomed out, or was hard to screw in, means you are going to have a tough time with it. Make a guide, or a jig, or pay someone else to deal with it like others have said. The fact that the old one was tough coming out, and the one that snapped was tough going in means the threads were damaged somehow.

If it makes you fell better, I probably would have broken off a tap trying to clean the threads for the new stud.

[sc_rufctr]

Originally Posted by Tidybuoy

I thought I had bought "High Quality" as I purchased them from, Pelican and they are listed as Genuine.

I'm sure the genuine ones you bought are good but the picture of the ones I posted are the "Non-corrosive exhaust studs" for the 911.

They are "M8 X 22mm" How long are the 944 studs you bought?

Porsche 911 & Carrera Pistons, Cylinders, and Heads - Page 6

[Tidybuoy]

Originally Posted by sc_rufctr

They are "M8 X 22mm" How long are the 944 studs you bought?

Mine are 46mm long.

I'm glad I saw your post because I just realized that I forgot to use washers.

[sc_rufctr]

Originally Posted by Tidybuoy

Mine are 46mm long.

I'm glad I saw your post because I just realized that I forgot to use washers.

Studs are measured from the part that protrudes from the alloy to the tip.
Not the overall length.

~~~~~~~~~~~~

I'm sure the ones you bought are fine. After all, they are OEM Porsche.

[nocarrier]

In a past life I used to repair impeller housings for the marine industry. I was constantly dealing with snapped off stainless steel studs and bolts that were bonded to the housings from the salt water.

There are many ways to tackle this, some may be better than others.

I would at least give it a shot before removing the head.

I am not sure about your car but can you release the motor mounts and possibly tilt the engine using a floor jack to get some more room?

Can those lines be moved out of the way?

First and foremost, you must be extremely patient. As soon as you start feeling anxious, you need to walk away, take a break, gather your thoughts and come back at it.

This procedure takes finesse or a certain "feel" if you will. The last thing you want to do is break off a drill bit or an extractor inside there. Furthermore, don't even think about using cheap tools! Forget Harbor-freight, craftsman, or the likes. Find a snap-on truck in your area. Most of the time you can meet the snap-on guy somewhere on his route.

DO NOT USE THOSE CHEAP EZ-OUTS they sell at the hardware store.


First thing i would do is try and move the stud with a sharp high quality pick. Even if you can get a turn back in, that would be a great start.

You can also try and apply some heat to the area around the stud. A little heat can go a long way.

Couple the heat with a bit of penetrating fluid as well.

It's hard to tell in your picture but in order to get the center on a broken bolt or stud, you may need to grind the top flat a little so your center punch, drill, etc doesn't wander due to the irregular surface.

+1 on the left hand drill bits also. Start with a small bit first. Like superman suggested, I have personally experienced stuck bolts or studs extract during the drilling process.

Remember, you can always cut the drill bits down in order to help with the clearance problem.

+1 on using the air tools as well. I find the electric drills and rotary tools are harder to control or "throttle." You'll probably end up bouncing all over that stud with an electric tool.

You can find a reversible right angle air drill. They are not too expensive.

While you are drilling, use a good cutting fluid. I like "tap-magic." Take you time don't go too fast or let the bit get too hot or you'll end up breaking the bit.

It may also be a good idea to have a spotter if possible. The spotter can help you make sure you are drilling as straight as possible by looking at the process from another angle.

This would be my first plan of attack.

[Shuie]

Originally Posted by tidybuoy

thought of trying somehting like this:

yes!

[Brando]

When pulling head studs, definitely use a tap and chase the threads.

Luckily I didn't have to learn that lesson the hard way...