Crack in the ehaust port

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Anonymous

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I have a D7 head that I had Bead Blasted. After getting it back from the shop and inspecting it, I found a crack in the 3,4 exhaust port in the ribbing. I am wondering if anyone has welded in the area, fixig the crack then adding a Port Divider with success? I sure hope so.
Thanks, Ken
 
I haven't welded to these particular heads, but I don't see why it would be a problem.

With the correct process. I don't think MIG welding it would work pretty well.

I have had good luck welding cast Iron with a Silicon Bronze rod.

Thing with Cast Iron is you have to make sure it doesn't get too hot, or it starts to sputter and splatter all over the place.

TIG, of course.
 
Hey Bort62,
Do you preheat the cast iron area you are welding? I am interested in learning somethins new.
Thanks,
Ken
 
I have actually had success without pre-heating.

The reason to pre-heat (with iron) is to keep the weld area from cooling down too fast and cracking. I have found that if you keep the weld zone from getting too hot in the first place (and from getting too large) it has the same effect.

So weld a little at a time, quickly, and let it cool.

A lot of people think you need to cook the crap out of something to weld it, but with a low thermal conductivity metal like iron and a well controlled heat source like TIG, you can actually keep it pretty cool.
 
I should mention that I have only tried this when welding small cracks etc. If you are trying to weld two large pieces of cast iron together, that is going to cause you to dump a lot more heat in, and as a result, risk cracking.

So if I were trying to weld two half's of a head together, I would suggest a solid pre-heat and post-heat. However, if you are just welding a crack in a head you don't need it.
 
I've had luck welding large areas on cast iron. I use an AC buzzbox set to 90amps, and a 99% nickle rod. Weld an area the size of a pencil eraser, then immediately peen with a chipping hammer. If you can touch the welded area right after peening it, it didn't get too hot. Go slow, move several inches away each weld (if possible, if not, wait several minutes between welds) and check temp after each weld. The repair will be ugly, but thats what grinders are for....
 
Thank you all,
I am going to have the head repaired then add a port divider.
Thanks again,
Ken
 
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