Brazing D2 radiator bottom tank

i'd put a soldered patch on it, will that wrk on cast?

Neil, how about JB Weld, that might seal better, I'd soak the parts in citric acid for a week to remove the rust, pressure wash then glue with JB, or bronze weld if that is what the experts suggest, at least with JB Weld you can create a larger patch over and around that nubbin, I've got some tanks here with the same damage.
Regards
Mike

what is the material ?? cast iron??
i had on a cast iron radiator underblock of my cat 15 wich plug treath was olmost gone, and i took a new piece of pipe with treath inside( i bought this) and welded it on to the underblock, on top of the old hole. now it is perfect!

3 questions that need answers to make sure we are all on the same playing field.
You want to put back the part of the tank that had threads in it? This piece is going to be re-attached to the inside of the tank? Then you will screw a bolt up into the repaired portion to hold the radiator onto the tractor?

[quote="drujinin"]3 questions that need answers to make sure we are all on the same playing field.
You want to put back the part of the tank that had threads in it? This piece is going to be re-attached to the inside of the tank? Then you will screw a bolt up into the repaired portion to hold the radiator onto the tractor?[/quote]

Yes you are right, I was assuming it was one of the small 3/8" holes.

Hi Jeff, yes - spot on. One of those (maybe) half inch bolts on the bottom of the bottom tank that bolts it to the radiator support.

sorry, i tought you ment the plug hole to let go of the coolant, but its the mounting hole,
could you drill it out and tap a new treath one size bigger , and drill out the mounting iron aswell to install the bigger bolt? then no need of brassing, or you can install a helicoil?

I'm not sure what the problem is but I have welded the top and bottom tank with low hydrogen rods and not had any issues. Some pre heat was used and the main thing is to cool it slowly. Weld in short 25mm runs allowing time in between runs.
If the end has popped off the bolt hole causing as leak, just put thread tape on the bolt or other wise install a heli coil as suggested.

I agree with Inter674 that thread tape is probably the easiest and safest way to go.
But if you are determined to braze it. Cleaning preference is strictly up to you, I usually sand blast, but there are many ways to clean rust off. Put a little bevel on the corresponding parts. Then screw it together with a pre-center drilled soft bolt. Reason being that when you go to braze it, it may wick into the threads effectively locking the bolt. Hence you will need to drill it out and chase the threads.
It should be evenly heated in the grill to drive out moisture to around 250 degrees F. then after brazing, put it back in to cool as the fire dies out. As far as brazing rod, I am sure there is a welding expert here that may give you the correct type but I have gotten away with whatever brazing rod is sold as general purpose.
Last one I did was thread taped as I figured there are 4 bolts total to hold the Radiator on.
BTW is this on which tractor? Not that it makes a difference, just curious.