Posted by David Sherman on Tuesday, May 02, 2006 at 9:55PM :
In Reply to: sealing up pinholes in oil pan posted by jim in n.y. on Tuesday, May 02, 2006 at 8:57PM :
I too would try solder. Did you clean it well with solvent, brush it with a wire wheel, and flux it up good? Use strong acid flux, not the rosin electrical stuff or even pipe-soldering flux. The old-time tin shops used zinc chloride. I've made my own by dissolving zinc scraps in hydrochloric (muriatic) acid. I'm sure you can still buy it. The fumes are not fun to breathe, but it'll clean steel better than anything else. Ammonium chloride (sal ammoniac) is also good for steel. To solder something like this, put flux on the part you want to solder, then apply a propane torch to the back side while rubbing the solder on the front side until it just barely melts and gets sucked into the joint. It's impossible to solder well if you're sticking the solder into the flame.
I temporarily patched a punctured oil pan with black RTV (silicone), but I would not trust any kind of silicone, epoxy, or other plastic-type sealer to hold up forever on an oil pan. You would have to get it scrupulously clean for anything like that to stick, and if you got it that clean, solder should stick as well. Best to use 50/50 tin/lead solder for this, not the "safe" plumbing solder they sell nowadays. The "safe" solder is more brittle and could crack due to the stress of tightening down the oil pan bolts and vibration.
If you're still having trouble, a radiator shop should be able to do it. They have the hot tank to clean it thoroughly and they know all about how to solder well.
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