so i picked up a spare valve cover to practice on before i weld bungs and such on my good one. following the settings on the machine, it does nothing but bubble up the surface. so i adjust the amps and it does the same thing, just less bubbly at less heat, and more when more heat is applied. i have no idea what the problem is. 3/32 red tungsten, 3/32 4043 filler rod. as low as 30 amps, as high as 200. i even messed with the gas a little. bringing it from as low as 10, and as high as 30cfm. tungsten is clean and sharp, valve cover is clean, but same result comes from uncleaned surface. seems like it bubbles up before getting the chance to form a puddle

 

You need to preheat the valve cover.
Also it needs to be really really clean since oil absorbs into the casting. You also need a dedicated brush to clean just one type of metal.

How I clean things is we have an ultrasonic heated immersion tank for cleaning stuff. It can take the most stubborn of things out of cast metal. If I cant get to the cleaner I use a wire wheel, then hit it with brake cleaner or acetone. Then if it still isnt clea. I try a scotchbrite pad then clean then I use a wire brush then clean.

 

i cleaned it quite well IMHO, but it seems that it should be preheated before hand...is it common to have to preheat valve covers prior to welding? what methods do any of you guys use to preheat them?

 

Its cast aluminum. It needs to be preheated. We put parts in the oven lol.

You really need to let it cool slowly after welding. People put smaller parts in sand, I would put it back in the oven (with it off) and let it slowly cool back to room temp

 

ball-park what temp the VC should be at when it is good and preheated?

 

Crap I can't remember exactly. I want to say 225-250 but let me see if I can find out for sure

 

i weld cast all the time with no preheat and no issues. if its a b series valve cover then thats how they are.... dirty porus aluminum thats spits and pops and turns black, they suck. ive never had a b series weld smooth before. k's on the other hand weld really well.


mike

 

Try to angle the torch so the arc is hitting the bung. Then let the filler wet in on the valve cover. Hope that makes sense!

 

i'm not welding anything onto it yet. i am using a junk VC right now to practice on before welding anything to my good VC. i have 1 -10 bung to weld and a couple holes to fill on the good one

i've tried all sorts of angles, gas pressure, amps, clearance effect, the higher i go on anything appears to make it worse. so it seems that no matter what the amps, it only bubbles up and never creates a puddle

 

Best way is to actually grind down a little bit and try to get to get to some of the contaminants that way. You can also do some cleaning passes with your torch. Low amperage and just work around where you want to weld, should start to see clean aluminum after a few times around.

D and B series valve covers are no fun. Kseries weld pretty nice usually, and so do their oil pans.

 

i turned down the AMP's to like 20 and was still having issues. guess i'll hit with my angle grinder and scrub it real good this time around with Acetone and see what happens. i know that contaminants will make your welds pretty nasty, but i've never heard of them causing the material to bubble up and rise like it does. might beable to get a video as well if it still does it after a grind and clean

 

you're preheating, be it with oven, gas torch, tig torch, to try and purge oil and contaminants that have gotten into the porous aluminum from being used. Clean, heat, clean, weld. Don't be discouraged if it still pulls in oil after you heat it, thats the way it is. Valve covers never weld like a new unused piece of stock. You're prolly doing alright if you listen to the above advice.

 

Like others have said, the valve covers get pretty nasty. When welding a bung on them I scotch brite them and wipe down with brake clean, both bung and cover. Then I concentrate the heat on the bung and drag the puddle down onto the valve cover and jab the filler in at the same time. This way I get more clean metal melted in than the crap underneath.