Exhaust/Cylinder head studs

impmad2000 · Post by **impmad2000** » Fri Aug 20, 2004 4:09 pm

I already assume that shearing off 5 of the 6 studs that fix the heat exchanger to the heads is not good....

Anyone got any top tips for removing the remains of the studs before I and up shearing them flush with the head ! At the minute I have 5mm or so stub to play with.

TIA

Alan @ CanfordClassics · Fri Aug 20, 2004 5:36 pm

Have you got enough there to weld a nut to it and also use a little heat to help things along. If you have the heat exchanger off now its a easier to get in there and also get better leverage. Beyond that they will need drilling out.

Sorry

Alan.UK

impmad2000 · Post by **impmad2000** » Fri Aug 20, 2004 6:39 pm

Yes, heat exchanger is now off, so at least I can see what I'm doing. I think I have enough to weld a nut on. This will also heat things aswell. I'll try this first. Thanks.

impmad2000 · Post by **impmad2000** » Mon Aug 23, 2004 9:25 am

OK ! so welding on a nut didn't work.... The studs just kept getting shorter

Drill and re tap or drill oversize and heilcoil ? How deep do I need to go ? Any ideas.... how much margin for error is there ?

Any help/experiences welcome

Cheers

Lightweight_911 · Post by **Lightweight_911** » Mon Aug 23, 2004 11:09 am

Tim - drilling out the broken studs 'in situ' is awkward but not impossible. I've done it successfully a number of times.

The key to success - or at least one of the main criteria - is to have high quality drill bits. I used 3 progressively larger bits - from memory 4, 6 & 8mm. Start off by centre-punching the stud in question. Then beginning with the 4mm drill bit (& using either some oil or cutting paste on the tip) drill up slowly ensuring that you stay central - I drilled up about 2cm.

Then repeat the procedure with the 6mm drill bit.

Finally use the 8mm bit.

If you're lucky you should then be able to pick the final remnants out of the threaded hole with a sharp 'pick'.

Good luck !

Alan @ CanfordClassics · Mon Aug 23, 2004 11:33 am

The drilling procedure worked for me in the past. As Andy says start by using a centre punch and then keep the drill nice and straight.

Good luck

Alan

Nick Moss · Post by **Nick Moss** » Mon Aug 23, 2004 10:04 pm

I have heard that the perfect solution is "Spark Erosion". It removes the stud without touching the aluminium/magnesium case. I am going to try it with some broken exhaust studs this week

Lightweight_911 · Post by **Lightweight_911** » Mon Aug 23, 2004 11:30 pm

Nick - I think Tim was looking for methods that he could try at home without further dismantling.

impmad2000 · Post by **impmad2000** » Tue Aug 24, 2004 8:37 am

You are right Andy, Don't want to take it apart if I don't have to.

Spark erosion is certainly the best way to remove a stud, but requires the item taken to a specialist. If you snap off an "easy-out", one of those reverse thread things, then it is probably the ONLY way... as the Easy-out is rock hard !!

I have now borrowed a helicoil kit, and am going to set about carefully drilling them over the next few days.

Where is the best place to get new gaskets, studs and the Allen head bolts from ?? OPC, Berlyn services somewhere else ??

Cheer for the help

Airhead · Post by **Airhead** » Mon Sep 13, 2004 1:05 pm

I've dealt with this before using plenty of penetrating fluid, some mild heat, freezer spray and a hammer. being able to weld a nut on gives you a real good chance, otherwise I use a pair of decent grips. Let penetrating fluid soak for as long as possible, then give the stud a few sharp blows with hammer and a punch, weld nut on and use a spanner, tapping the spanner with a hammer instead of putting a steady force on it is more likely to work and not break the stud again. Warming the area and then cooling only the nut/stud with a freezer spray (with straw attached) will help too.

Failing that, file the end off and then centre punch and drill out with progressively larger bits, an appropriate sized tap and some lubricant will help clean the threads out afterwards.Whatever you do dont drill it oversize....if the thread ends up being damaged then helicoil it so you can use the same size studs........good luck

impmad2000 · Post by **impmad2000** » Mon Sep 13, 2004 1:34 pm

Thanks for the advice. It is now fixed. Drilled and helicoiled.
Back on the road