TR2/3/3A exhaust manifold with rusted and broke studs

[sp53]

On a tr3 exhaust manifold with rusted and broke studs, I seem to remember a method for removing them that used some short of high heat or scarfing deal that was usually available at machine shops? Or I am I stuck with drilling and tapping?

 

[Geo Hahn]

A decent machine shop should be able to handle this just fine. The work will be easier for them (and cheaper for you) if you not break off an EZ-Out in there before you take it in.

If there is anything left to get hold of they will probably get it really hot to unthread it.

If it is broken off flush they may weld first a washer, then a nut, to be able to unscrew it.

 

[TR3driver]

Yeah, I don't even bother trying an EZ-out any more, for just that reason. Plus I have yet to ever have one work on rusty threads.

What I do is to drill undersize, then progressively larger until the drill just breaks through to the original threads. Usually only along one side, as I rarely get the centering perfect by hand. Then use a dental pick to break away what is left of the original stud. I've been lucky so far, always managed to save the original threads.

Last time I talked to a shop about it, they were going to just drill and install a Heli-coil; and charge more than I felt the manifold was worth.

 

[sp53]

Thanks you guys that is kinda what I figured. And yeh Randall I do it the same way. The last time I broke an easy out off I ended up with a hole half again as big with threads only about ¾ remaining. I did get the one really bad one to turn about a ¼ turn after a lot of heat, but I think the stud is egg shaped and I will keep at it. I do have another exhaust manifold, but cosmetically the casting is much rougher with a lot of pitting.

I thought there might be some kind of heat/blasting tool that got the stud hot somehow and blew it out without damaging the casting, must have been one of those dreams from the sixties.

 

[CJD]

For this project I was 1 for 3 in getting the old manifold studs out. I've come to expect it on manifolds. My "standard" is to go in the following order:

I try to remove them normally after a long soak with PB blaster. Then, if I can sense that the stud is locked in, before it just snaps unpredictably, I heat the stud red hot with a torch, allow to air cool, PB blast and try again. After a couple tries, the stud is inevitably broken off at this point.

The key to a good drill out is grinding a nice flat on the broken stud and then center punching on the fresh flat spot. This allow you to get the drill as centered as possible, which makes it easier. Normally I work the bit size up slowly like Randall...and am able to run a tap to clean the threads if I got the hole centered closely enough.

I have to say, working on 50 year old Triumphs has really brought my drilling skill to another level!

 

[Geo Hahn]

...before it just snaps unpredictably...

A side note - a local mechanic/friend who wrote a book about working with LBCs said that when he hires some young new guy he has them practice by clamping old bolts in a vise and wrenching them until they break. The idea is to give them a feel for the difference between a bolt that is twisting and one that is turning.

I used such a practice session prior to some work on my non-British vehicle with a pair of long thermostat housing bolts that were notoriously soft. Seemed to help or maybe it just kept me busy long enough to give the PBlaster a chance to work.