Exhaust studs

CraigH · 06-20-2005, 09:52 AM

Unfortunately I broke two exhaust studs while removing my heat exchangers over the weekend. One barrel nut and one regular hex nut. I soaked the nuts for a while with PB Blaster AND did the heat/cool cycle while removing them and two still snapped. One was partially my fault as I likely put a little too much angled pressure on it but with the other one, I dont know what I could have done differently.

Anyway, I know it has been discussed quite a bit, and I have looked at many of the old posts, but there seems to be a difference of opinion on what the potential issues are with driving the car with the broken studs. Everyone seems to be in concensus that they need to be replaced at some point, but what is the worst case hazard with driving as is? Luckily, the breaks were on two different cylinders and I have a fair amount of stud left, so the fit is fairly tight with the new Heat Exchangers installed. My bottom line is I would like to put off any major engine work until the winter months.

Thanks for any help.

911mot · 911mot's Garage

If it's not leaking from the exhaust to head flange then you are good to go. Worst case is a nut coming loose and the exhaust starting to blow.
You were lucky. Mine snapped too short to be re-used and I had to drill out the offending studs and helicoil them.

Drilling perfectly square down the centre of the stud can only really be done with the engine out and upside down though.

Vipergrün · 06-20-2005, 10:49 AM

I had a broken stud. I got some good bits and started small and worked my way up, then I was able to use an extractor. I did this all free hand, under the car. Not even slight galling on the threads. The pilot hole is key and you do not have to go that deep. Your milage may vary, but it can be done.

RoninLB · 06-20-2005, 11:04 AM

A Quiet Boom/ Chris mfg's a model specific broken exhaust stud removal fixture.

juanbenae · juanbenae's Garage

somebody around (shuie possibly) here produced a jig to guide the drilling. knowing pelican one of the guys would loan it to you for cost of shipping to & fro. do a search for "broken exaust stud" and you can become enlightened.

LakeCleElum · 06-20-2005, 11:07 AM

Use a "cobalt" drill bit, a careful center punch and a steady hand. You be amazed at how fast these bits will drill out a stud.

bell · bell's Garage

Quote:

Originally posted by RoninLB
A Quiet Boom/ Chris mfg's a model specific broken exhaust stud removal fixture.

very slick piece he has there, i too have a few broken studs and will be using christians fixture to fix it....cause if you screw up drilling out the old you're ....well.....screwed

CraigH · 06-21-2005, 04:24 AM

Thanks for the responses. I really want to put this off until later in the year as there have been some beautiful driving days here of late and the car was in the garage waiting for new heat exchangers. I havent had anyone indicate doom if I drive it with no apparent leaks at the flange.

Also, what is "A Quiet Boom/ Chris mfg's" stud removal tool? I did a search a couple of different ways without much info.

bell · bell's Garage

here is a thread with christians tool, last page has the info you need.
http://forums.pelicanparts.com/showthread.php?threadid=192188&perpage=20&highlight=tool&pagenumber=1

A Quiet Boom · A Quiet Boom's Garage

I do manufacture a tool to remove broken studs based on a design by John Walker. I have two versions one is model specific and runs $125, the other has interchangeable disks for various port sizes and runs $150 with a single disk, other disks are always available. You can reach me at rsr911@neo.rr.com

-Christian

CraigH · 06-22-2005, 08:57 AM

Thanks Christian. I bookmarked your address. I havent decided if this is something I will tackle myself or have my local custom exhaust shop work on. Either way I will likely get the tool for you when the time comes. Will the tool work well with limited clearance under the car in my garage (i.e. car up on ramps or jack stands)?

A Quiet Boom · A Quiet Boom's Garage

Craig,

The tools main purpose is to be used under the car with a hand drill rather than removing the engine. As long as the car is high enough to get under with a drill the tool will work just fine.

-Christian

CraigH · 06-24-2005, 06:32 AM

I got everything back together, at least temporarily. Still got the two broken studs, but it seemed pretty tight with all new nuts and gaskets. Ran the car a bit and the engine had a distinctly different sound. Much "clickier", kind of like an old VW Bug. I am quite new to the 911 and dont have much baseline to compare to, but I assume this means I have some leaks at the heat exchangers. Like I said, the problem is I previously had leaks all over the exhaust, hence the change of Heat Exchangers, pre-muffler and muffler, so I dont have anything to really compare to.

Any thoughts are appreciated.

Zeke · 06-24-2005, 06:52 AM

"Any thoughts are appreciated."

You won't be able to keep exhaust gaskets from blowing out and you're gonna have to live with the 'ticking' and worse until you do this right. Plus some backfiring from the air leak is very possible and that doesn't do your muffler any good.

I'd fix it.

afterburn 549 · 06-24-2005, 06:56 AM

dont forget to use a left handed drill,as it will lots of times on screw it as you go thrue,and as a thought I do not think you used enough heat in the begaining

CraigH · 06-24-2005, 07:04 AM

Thanks Zeke. I figured that was where I was at, but didnt really want to say it out loud. Now I just have to decide whether to get Christian's tool and attempt it myself or bring it to a local exhaust shop.

Afterburn - Thanks for the tip. As far as heating, maybe not, but I did heat cherry red and cool 4 times each before attempting to remove. The one side, where both studs broke, was pretty rusty.

Tim Hancock · 06-24-2005, 07:07 AM

When exhaust nuts are heated bright red they back off easy. Putting a wrench on anything less than glowing red exhaust manifold nuts is asking for trouble! (ask me how I know!)

A Quiet Boom · A Quiet Boom's Garage

Craig,

I've just sent a tool to another Pelican member, I imagine I'll hear from him by Monday as to his results. Not trying to push my tool but I agree with the others, get this fixed soon. I drilled a head today in about 15 minutes, it was of the car and will be part of my display at upcoming swap meets. One note, do NOT use a left handed bit with my tool. Yes they do sometimes work but with my tool they will cause problems, you just need a good quality bit (carbide is best) for use with my tool.

The problem with leaky manifold gaskets is that on most cars the can lead to overheating the exhaust valves and potentially causing damage. I know this because I ruined two valves on a 302 Ford years ago when I installed a cheap set of headers and just put up with the "ticking sound".

-Christian

gerard vaglio · 06-24-2005, 07:27 PM

Okay, I know this is the slobs way out but you asked.

I broke one of my head studs and to avoid exhaust gases leaking out I did this untill I could have it drilled out (months later).

Get some black silicone head gasket sealer that you find at an Auto Zone Pep Boys type of place. Put some of it on both sides of the exhaust gasket so that when you tighten up the exhaust it oooses out just a little and seals things. Let it cure overnight.

Mine didn't leak or backfire on deceleration. In fact, we had trouble removing the nasty black stuff months later when it came time to drill out the stud. I was amazed at how well the stuff held up.

I'm not proud of this but it did work.