AC78 Posted 12March, 2018 Report Share Posted 12March, 2018 Some of my exhaust studs are badly corroded. They will still hold a nut but i'm wondering if I should replace the really bad ones while I have my exhaust off. The risk is that they snap during removal, so wondering if I take the risk or leave them alone. Thoughts? Thanks, Alex Link to comment Share on other sites More sharing options...
Skidmarks Posted 12March, 2018 Report Share Posted 12March, 2018 18 minutes ago, AC78 said: Some of my exhaust studs are badly corroded. They will still hold a nut but i'm wondering if I should replace the really bad ones while I have my exhaust off. The risk is that they snap during removal, so wondering if I take the risk or leave them alone. Thoughts? Thanks, Alex If it isn’t broken, don’t fix it! Careful when torquing the nuts as things could still end badly ... And check that your torque wrench is correctly calibrated. Link to comment Share on other sites More sharing options...
AC78 Posted 12March, 2018 Author Report Share Posted 12March, 2018 Thanks Skids. I'm a big fan of the 'while you're in there' but as I have already broken and extracted one stud i'm not keen to go through that again. Right now I have good access to and fully exposed studs to work on. If I have to remove the exhaust in the future there's a good chance some of the existing studs will snap no matter how careful I am, hence my dilemma about replacing them now. Link to comment Share on other sites More sharing options...
Mike D'Silva Posted 13March, 2018 Report Share Posted 13March, 2018 Is the engine in the car? Link to comment Share on other sites More sharing options...
Pauly Posted 13March, 2018 Report Share Posted 13March, 2018 there's the "if it aint broke, dont fix" line. or there's preventative maintenance. I'd fix them IMO. Get some stainless steel ones so they wont corrode in the future. put some anti seize paste on it and they'll be good next time you need to remove them. To remove them, spray with WD40 and let them soak. lock 2 nuts against eachother on the thread and use 1 nut to remove it. Link to comment Share on other sites More sharing options...
AC78 Posted 13March, 2018 Author Report Share Posted 13March, 2018 1 hour ago, Mike D'Silva said: Is the engine in the car? Yes Link to comment Share on other sites More sharing options...
Mike D'Silva Posted 13March, 2018 Report Share Posted 13March, 2018 When I had my engine apart, I had a go at doing this.. I consulted a machine shop for advice which was to give the studs a really big hit with a hammer to shock them and hopefully break any rust or corrosion holding them in, and then to soak with pb blaster for a week or so.. I had the heads on the bench and stood them up so the liquid would hopefully work its way down inside. After a week, I put two nuts on and ......................nothing. Ended up damaging the threads more... I couldn't budge them so I took it to the machine shop who had to drill them out.. he said that the exhaust studs on 911 heads are some of the most problematic ones you can find. I was happy to pay him. Link to comment Share on other sites More sharing options...
Pauly Posted 13March, 2018 Report Share Posted 13March, 2018 47 minutes ago, Mike D'Silva said: When I had my engine apart, I had a go at doing this.. I consulted a machine shop for advice which was to give the studs a really big hit with a hammer to shock them and hopefully break any rust or corrosion holding them in, and then to soak with pb blaster for a week or so.. I had the heads on the bench and stood them up so the liquid would hopefully work its way down inside. After a week, I put two nuts on and ......................nothing. Ended up damaging the threads more... I couldn't budge them so I took it to the machine shop who had to drill them out.. he said that the exhaust studs on 911 heads are some of the most problematic ones you can find. I was happy to pay him. If this is the case with 911 studs, i'd leave them unless engine is out in pieces. Re tapping ect for someone at home is not an easy job considering having the engine in ect and probably no hoist. Im lucky i've got a hoist at my shop with an engineering shop ect so doing anything isn't difficult. Link to comment Share on other sites More sharing options...
AC78 Posted 13March, 2018 Author Report Share Posted 13March, 2018 I should have said earlier that the car is a 79 911, and from what I can tell the exhaust has never been off before. The stud that snapped took me a week to get out. I soaked it daily with an acetone/ATF mix and gave it regular hits with a BFH. On the seventh day (following church (crucial step)) I heated around the stud with a propane torch and used a set of vice grips (there were no threads left) to wind it out, and it worked! Dunno if i've got the courage to try it again though. Link to comment Share on other sites More sharing options...
Harvs11 Posted 13March, 2018 Report Share Posted 13March, 2018 Heat is your friend. Don’t be afraid to get the surrounding alloy (or rusted on nut) cherry red. Propane is good as it isn’t as severe as any oxy. The heat will break down the rust and the heated base metal will expand thus relieving the grip on the thread. Link to comment Share on other sites More sharing options...
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