Join Date: Jun 2003
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Welding pumpkin caps
Just want to get an idea of how others have welded the pumpkin caps.
Originally, I considered draining the gear oil, welding the cap on, then refill.
Then I thought that gear oil may help diffuse some of the heat, helping to protect the front of the thin stock differential. I figured I could just replace the burnt gear oil with fresh stuff when I was done.
I opened the fill plug (wasn't going to trust a 15 year old breather to vent the excess pressure). I lightly placed a paper towel into the fill hole, so that when the oil expanded it wouldn't drain onto the area that was being welded.
Everything was going very well, the beads looked very nice, good penetration, etc. I ran about an inch on one side, then an inch on the other, then allowed the whole thing to cool for a few minutes. I went back and forth like this a few times until I had a decent length of bead down both sides.
I started running a second pass, when all of a sudden I heard a loud "BANG"! After checking to make sure I still had 10 fingers, I flipped up my welding helmet and looked at the pumpkin. Everything looked OK, but the wad of paper towel in the fill hole was missing. I found it across the room. I guess the paper towel swelled up enough to plug the whole, and the pressure shot it out. I finished up the second pass on both sides, and it looks like it should hold very well.
Since I need to weld caps on 2 more zuks, I just wanted to see if anybody has a better method. Should I drain the oil first?