the other day i was welding 10an fittings into a k series valve cover.. well everything was going well and when i was finished i walked away from it to let it cool and i heard a little pop sound.. didnt think much of it and walked back to the vc to look over it and it split from the weld almost all the way down to where it sits on the head.. i have welded fittings into vc's and never had a problem till this one.. im just trying to figure out if it was something in the cast or if i did something wrong so i know not to do it again. i just picked up a tig like 6-7mths ago and im still learning so dont hurt me to bad..lol

 

Pics of the crack? Also could be the amount of filler used, maybe not enough? Or not enough penetration to the VC itself.

 

Could be wrong filler, what did you use?

 

The welds themselves didn't crack.. it was the valve cover.. them I tried to grind the crack to a V and weld back over it and the weld split in the center when it cooled .. so it ground it again and tried once more then the bitch cracked beside the weld.. its crazy.

 

sounds like the problem is in the casting. i've had cast iron do that to me before. you using 4043 filler?

 

I don't remember what rod I have. I'll have to look

 

I used 5356 rod.. could that be an issue

 

Use 4043

 

Yep, wrong filler all the way.
5356 is best for anodizing and room temperature service on structural stuff.
4043 is better for moderate heat service and castings(good ones).
Some castings need more silicon to deal with hot cracking, so 4047 works fantastic.
It's a brazing alloy actually, so it has a very similar silicon content to most castings (10-13%)
4043 has about 5%.
5356 is not a good choice for castings at all. It also does not like longer arc lengths.
4043 tends to flow better because of it's intended uses, and is less arc-length sensitive.

 

What he said!

Justin, the first time I welded fittings to a D17 valve cover, the same thing happened! Freaked me out!

 

Well now I know. So should i pretty much use the 4043 on pretty much everything like charge pipes and such

 

i use 5356 alot cause i do a good bit of areospace work, and that is the filler the parts call for. i have welded valve covers and trans castings with it before because i am use to grabing it. the 4043 is proper to use on castings, you will notice that it melts alot faster than the 5356. you should print yourself out a chart of what material/fillers go together. i keep them in my office for all types of alloys because it is too much to remember all of them.

 

good idea.. im going to look on some of the welding sites to see if i can find a chart