Cast iron repair?

   / Cast iron repair? #1  

Arc weld

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Edmonton, Alberta
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MF 135
There's a lot of smart guys on this forum so maybe they can help with my repair. I have a Cat track loader with a 3204 engine. I just put new check valves in the transfer pump but had to remove the bolts holding the oil cooler on so I could get the bottom bolt for the transfer pump out. I got it all back together and everything seemed fine, no leaks. I was going to go try it out and drove about 100 yds. I thought I'd check again for any leaks. No fuel leaks but oil was leaking. Closer examination showed that the top mounting tab for the oil cooler had pulled right off.:censored: About 3/8" thick. It looks like a spacer because it was such a clean break. I think it's a 5/16" bolt that goes into it. I need to fix it and it's cast iron. I don't know if I can tap it deeper into the housing or not. I read on the welding web about a guy doing a similar repair using nickel rods and just doing very quick welds so it doesn't get hot. I can take the transfer pump off but the injection pump is above that and I don't want to take that off. Looking for some good ideas on the easiest way to fix it. Thanks in advance!
 
   / Cast iron repair? #2  
Can you show a photo of the problem area?

There are several thread solutions but if the fix demands a weld that can get a little more complicated. I have had the most success with silicon bronze rod and TIG welding. Wouldn't want to try and tap it though.
 
   / Cast iron repair?
  • Thread Starter
#3  
Sorry can't show a pic. It's like a raised boss that's threaded for mounting the oil cooler and the bolt pulled the threaded section off. It's out at my property and I don't have a shop. I have a welder and a torch but because it's not too far from the injection pump, I don't want to get it too hot.
 
   / Cast iron repair? #4  
I wonder if you could back the injector pump bolts out a few turns and just break contact where heat would otherwise conduct from the casting ... and/or without tearing a gasket. (injector lines too stiff? can you loosen a nearby bracket/'loom' then too??) 1/16" would be plenty far away if the job went quick enough. (strategic toothpick spacers?)

Cooling the welded casting gradually enough could be as important to minimize stress around the weld as getting however hot you might preheat locally with the torch, and an extra pair of hands on scene could be most helpful when you're ready to strike. btw: Our tool & die welders would use the 'nickel' rods on cast Iron. There may be ones that require the least preheat or would 'stitch' the best if you don't do much of that.

I'm thinking you might not have to tap anything. Can you: 1) reach to weld/stitch all the way around the boss? 2) Thread the boss onto a bolt and into a remaining deep thread or two and snug it down nice with/vs clamping? If not so easily aligned perfectly you could still chase-out with a tap to assure clean threads to the most depth.
 
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   / Cast iron repair? #5  
I can't weld a lick but have supervised welding and maintenance groups for decades. The welders and maintenance people prefer brazing over Ni-Rod for cast iron. Ni-Rod makes the cast iron brittle around the weld and it breaks easily. Brazing to them is a better long time fix. Again, I am not an expert. Just sharing an observation.
 
   / Cast iron repair?
  • Thread Starter
#6  
I need to find out if the part that the oil cooler bolts to is separate or part of the engine block. It's a kind of complicated. The oil cooler attaches to it and so does the injection pump. There's a drain plug in one end. I think maybe oil comes from the injection pump into it or from the oil cooler to the injection pump. If it is a separate part, it might be best to just replace it. If it is separate I hope I can get it aftermarket or a good used one. Cat parts are NOT cheap.
 
   / Cast iron repair? #7  
WOW! Not being in a position where you can use heat really limits the options. Only thing I can think of is some type of epoxy. Years ago before I ever bought my first aluminum Tig welder I had to repair an aluminum engine case that went on a motorcycle. I used a 2-part epoxy that worked great. Have no idea what is on the market now, that would work in this situation.:confused3:
 
   / Cast iron repair? #8  
.... welders and maintenance people prefer brazing over Ni-Rod for cast iron. Ni-Rod makes the cast iron brittle around the weld and it breaks easily. Brazing to them is a better long time fix.... Just sharing an observation.

Shield Arc, I worked in leak test/repair in the transmission plant before I went into the trade (Toolmaker). We'd use an epoxy to repair 'case' leaks (aluminum) between testing and the shipping dock. Porosity in pressure areas meant a teardown, but with 'trichlor' to clean/prep the area & a dab of silver paint on top for looks it worked for the rest. None of this was structural but it seems logical that brazing would adhere to CI well and provide some resilience for heat expansion at the repair site, so +1 on that. (I have seen CI brazed outside the toolroom)

btw: I wonder if too long a bolt (a replacement of yore) had bottomed out in the hole and pushed/snapped the boss off when fully tightened. I'd rather hear that it was a spacer and that too short a bolt didn't get a good purchase in threads below. (How thick or thin the 'parent' material is could demand some understanding/finesse, too.)

Can we help the OP post pics to tempt more welding guys into this exchange? (... if I didn't 'wonder'/ask so often I'd never learn much ....) :eek:
 
   / Cast iron repair? #9  
Cast iron or cast steel? Makes a difference in welding/brazing. My engine guy repaired a broken water pump casting on my Minneapolis Moline BF tractor using braze rod. He said it was cast steel.
 
   / Cast iron repair? #10  
Should be an easy fix. If you are not sure what the base metal is, Use MG600 or Missle Weld or Versalloy. 2 second tack welds all the way around. Silicon Bronze will work as well. All come in stick or tig. Make sure you have the bolt in there before you weld. After, Just snug it up with lock-tite so you don't need to reef down on it. Or I think someone mentioned welding a nut on in place of the boss. Same filler metals will work. Good Luck.
 
 
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