exhaust bolt horrors

[kevinham013]

as post in my previous post i twisted an exhaust bolt off trying to change a cracked pipe,,i got a real good set of easy outs from a buddy ,,took my time drilled through the bolt and and tried the easy out ,,,well wtf!! the bolt didnt break loose but the lobe that the bolt screws into on the cylinder head cracked..this is on the left side bottom bolt of course the hardest to get,,,so now ,grrrrr,,whats my next step,,,is this crack weldable,and then maybe helicoil,,or do i need a new head assembly,,anyone have ideas please...greatly appreciated,,,

 

[jamesc]

without actually seeing what you're working with it's hard to give good advice. i can tell you from years of experience ez outs have probably caused as many problems as they've solved. helicoils are not a particularly good fix there are better inserts such as timeserts but every situation is different. timeserts require some depth to properly set them. i would say your worst case scenario would be to pull the head and have the boss properly tig welded. to do any weld repair you'll have to get the bolt out and get the area completely clean. aluminum welding must be CLEAN. if there is enough material you "might" be able to drill/tap deeper and use a longer or different diameter fastener. if this is even possible you must be careful to not drill into a water jacket or similar. any chance you can post a clear pic of the boss? i understand you might not be able to get a good pic depending on location

 

[kevinham013]

thanks jamesc,,, I talked to a engine rebuild shop they are pretty sure they can weld it up,,i just broke out a small corner, shape of a triangle,,so next step is to get the head off and over to them soon,,hopefully monday,,,,snow is on the way,,and thanks again for the info,,greatly appreciated

 

[kevinham013]

just updating ,,,i've got the cylinder head off,,,and the rest of the corroded bolt out,,its not to bad ,,,threaded another bolt it seems to have enough threads left ,,but while its out ,,I'm gonna get the shop to weld the broken piece up and make sure the rest of the exhaust bolts will come out,,,fingers crossed ,,thanks

 

[gcr3903]

Heli Coil? Just to be safe.

 

[jtman04401]

Trick to take bolts out of aluminium heads and before you tell me I am crazy just try it.. Get a bottle of MAP gas or a torch and get the stud hot before you try to remove it. While it is hot take a normal table candle (long skinny ones) and rub it around where the stud threads into the head. Dont get the head to hot as too much heat can damage aluminium heads. But if you get it warm enough to melt the candle into a liquid, somehow the candle wax will travel up the threads into the head and the stud/bold will spin out easily. Do this b4 you snap off the bolt and you are golden.

 

[Len Todd]

Steel and Aluminum react to each other causing corrosion on the threads. The older the sled, the more this impacts you. Also, the two metals expand and contract at different rates. I have found for me, it is always best to run the engine and get the thing warmed up and then work on it. If you can not practically do this, then the stubborn bolts get a little heat applied directly (i.e. heat on the bolt and not the aluminum boss, etc.). Also, it helps a lot of one warms the enginge up and then hit all the bolts with some penetrating oil (Not WD40) and let it set overnight, before you work on it.