Exhaust Manifold replacement alternative method to drilling

[youngsyr]

Getting back on topic though - does an impact wrench not do well against these bolts?

I've always found that as long as you get a good 6 sided socket onto even the most stubborn of corroded bolts, it will typically get them out very quickly.

Conversely I've found that even getting good leverage and leaning on corroded bolts will tend to just sheer the head off.

 

[AntonyC]

Getting back on topic though - does an impact wrench not do well against these bolts?

I've always found that as long as you get a good 6 sided socket onto even the most stubborn of corroded bolts, it will typically get them out very quickly.

Conversely I've found that even getting good leverage and leaning on corroded bolts will tend to just sheer the head off.

The impact wrench just sheared the bolts when i used it, I was being as mechanically sympathetic as i could. In the past ive had great success with them on other cars. As you said, six sided socket is a must.

 

[AntonyC]

Well done!

I'm either going to have to get someone to do this or tackle it myself at some point in the next year or so. I've never had much luck drilling sheared bolts even with left handed cobalt bits. I find the drill goes off centre as often as it works which causes a major issue in aluminium.

I can weld (MIG) well enough but working on such an expensive engine does make me nervous.

I wonder if it's a good approach to take the view all WILL shear so just grind the rusty remains clean and weld an oversized nut on straight off?

I would definitely try and get the bolts out using penetrating fluid and a breaker bar.

I agree with you, drilling hardened steel bolt in aluminum is very hard and you're going to be fighting the drill. But the jig mitigates most of that.

 

[fot0]

Thanks for great post.

Having done this twice on two dropped engines I can sympathise. First heads I sent away for other work and broken studs were removed by them. They informed me that the studs were not square to the head from a previous repair so it was touch and go on a repair or scrap. Fortunately, they repaired them.

I am working on another set of heads, but will likely send them away to same machine shop.

 

[Kingb4]

Great write-up Op.

Its a good idea, that I havent seen mentioned much on this forum. Welding to broken studs is very common in other engine applications.
I also mig-weld, so will possibly try this method, if/when I attempt my manifolds (have resisted the urge to touch them).

Have you got any pictures of you welding a stud? Where did you attach the earth clamp?
Did you coat the gasket-mating surfaces with anti-splatter spray, which would hopefully reduce the impact of any splatter?

 

[UncleP]

It's a toss up between what I'm more paranoid about. A wandering drill bit destroying the engine or turning the heads to liquid with a welder.

 

[Luddite]

Just picked this thread up as it was about to drop off the bottom of the list...Great write up AntonyC and on a task that it takes a fair degree of courage to get into, GREAT that it worked out as it did .

When reading of this issue which seems likely to affect most in time, it reminded me of a similar task I performed on my pals 928`s water pump

The water pump was a nightmare of a job, as I think there were fourteen 6mm bolts holding it in place and perhaps at least four of the heads broke off flush with the pump, I ever treat rusted old nuts and bolts with a great deal of respect, regardless, there I was with the pump off and a few mm of four rusty set screws sticking out the front of a very expensive 928 block... I managed to clean the threads and screw on a nut to each of them mig welding the end of the stud to the nut, however no way were they coming out with as much force as I dare put on the 10mm ring spanner... I dug out my gas welding kit and applied heat to the area of the block where the bolt ends entered it.. very CAREFULLY. Anyone who has over heated an alloy casting knows it is there one minute and the next melts without warning... the idea of scrapping a 928 block made me very nervous indeed, all I could think to do was to put as much strain on the spanner as sensible for a 6mm bolt and kiss the block occasionally with the flame until enough heat had been applied that the bolt moved a fraction, and continue that process until I had withdrawn the offending remnants of bolt.... I was at it for ages, though was very glad to have completed that task,

Of course I was lucky in that the remnants of the set screws were threaded along their length allowing me to then screw the nuts on to the remnants when the heads had broken off. Just playing the gas flame as and when required to keep things moving was the really tricky bit as during the process of cooling the set pins would risk breaking if too much forse was applied when they stuck again...

Not sure if using a flame for the exhaust stud task would be more risky than welding...? Yeah, I have many a white dot on my chest from mig welding while lying on my back under my old sports cars... it`s all part of the game..