Good Methods For Removing Broken Studs

[matt_fp]

Several of our regular cars seem to be having issues recently with broken exhaust manifold studs.

Usual technique is to pull the head/heads off and drop them into the local engineering company - however this isn't really practical on some as its engine out.

The usual drill and tap method also isn't ideal due to lack of space and I'd rather not prat about with "easiouts" as they'll only break off half in the stud ;)

Just wondered if theres any really good 'in situ' methods we're missing out on. Obviously spark erosion is a possible, any tips for a good mobile guy around the Leics area?

Cheers
Matt

[GreenV8S]

matt_fp said:

Usual technique is to pull the head/heads off and drop them into the local engineering company - however this isn't really practical on some as its engine out.

I can understand how this might be a big job if you have an overhead cam, but for the rest of us surely the heads come off without any great difficulty?

As for broken bolt removal, it seems that sometimes studs come out with relatively little effort once the tension has been removed, in other cases tapping the exposed end with a drift may be enough to break the thread loose and slowly turn the stud. Failing that, heads off and do it the hard way.

[tvrolet]

Weld a nut (or bolt) on to the end. Obviously only worksa if there's some of the stud showing, and nut is easier as the 'weld' can go inside the nut on top of the stud, so less chance tagging the weld onto the head. I assume you could damage the head if you were to get things too hot, but a quick squirt with a mig won't do anything (or hasn't....to date). Plus a bit of heat on the stud has got to help too!

WB

[matt_fp]

GreenV8S said:

I can understand how this might be a big job if you have an overhead cam, but for the rest of us surely the heads come off without any great difficulty?

4 overhead cams, 24 valves and one of the heads is burried under a bulkhead.

The studs seem to be welding themselves in rather well, possibly due to that fact that EGT is 950 degrees+

Looks like doing it the hard way is the best choice then, welding a nut on would be possible on some aside from the fact theres no room for the welding torch!

Cheers
Matt

[Nick_F]

Tch.

People who put V6s in sideways deserve all they get...

Surely if the manifold fitted in there then you can get there with a MiG torch?

Sounds like you need a better solution when they do come out - maybe you should 'waist' the studs so that if they break they always leave a reasonable stump, and use softer nuts.

[steve_D]

When I were a lad it was common for the manifold to be fixed with brass nuts.
Later I had a VW Beetle which had helicoiled nuts.

Steve

[nighthawk]

Which easiouts are you using?

I favor the parallel fluted type from snap on, Use the guide to ensure you drill it as straight as possible and as wide as possible, then bang in the easiout and use 2 spanners to undo it.

I also use a compact 90 degree makita cordless drill which is a godsend in tight engine bays, and a selection of left handed drill bits, 9 times out of 10 the the drill will snag 1/2 into the stud and wind the stud out

Whats involved with spark errosion?
I've not seen that technique employed.....could that be used in such a tight bay, especially if the space is too tight for a MIG?

[denisb]

Slightly off topic but what is the engine?

I have a bit of a vested interest (Nissan engine with V6, 24 valves, 4 cams, one head buried under a bulkhead)!

[BliarOut]

Have you thought about a pre-emptive strike Matt? Use a nut splitter before you break the stud off if there's room. It would pay for itself pretty quickly.

[matt_fp]

Engines are Twin Turbo Duratecs in the back of Nobles.

Bliarout - unfortunately the studs have already snapped by the time we get to them so no chance to get George W (pre-emptive) on it. As it only seems to be happening on the older cars I have a theory that the steel the flange is cut from expands a little too much when very hot leading to too much torque on the stud, couple this with three years worth of hot/cold expansion/contraction and the studs fail.

Torch won't fit as there is an overhand over the top of the front bank turbo/manifold meaning you can't rotate the torch to get it on the stud and hold a nut on there as well - although I may have another go at doing it this way when the next one comes in.

A google for "Spark Erosion Technique" should give you plenty of info on how its done.

Best Regards
Matt