While happily pushing brush with the D6 (8U) on a logging job my old iron day was ruined when I noticed that I was leaving an oil trail.  Traced the leak to a crack on the No. 46 hydraulic control unit housing -- right side rear going from the bottom right up behind the mounting flange to top of flange.  Wasn't wide open but was putting out a slow steady 1/8 inch or so stream -- just slowly under gravity -- and everything still worked.  Took her back to the barn and pulled the grilles and front cover of the HCU to find that she'd been cracked for a long time -- with a weld running the whole way on the inside complete with a generous coating of Form-a-Gasket over the whole weld.  Whomever made the old repair did not weld the exterior and the crack is exposed.  I'm not very happy with the quality of the weld either -- it's spotty, not a smooth melted in pass almost like somebody was using a wire-feed unit and had the current rather low. 

From what I can see the crack has not extended past the weld however the new leak leads me to believe either the weld wasn't a complete seal to start with and the Form-a-Gasket failed or something, somewhere along the weld separated. 

Problem:  The crack, and old weld, proceed down alongside a housing and tube ass'y. (9F1559 tube ass'y., 9F1554 housing on the drawings in the tech library.)  and I can't weld with those in place. There appear to be two springs and seats inside that housing that worry me.  What am I getting into if I remove those things to get access for making a new weld?  I really don't want to release a high power spring and/or open a pandora's box that I can't put back together again.

I really do not want to have to pull the whole unit off the machine (which would be necessary to weld the exterior.)  With the heat involved I'd probably have to pull those items and clean out the trapped oil anyway.  My only other alternative that I can think of is to goop the heck out of the old weld and hope but that doesn't seem to be a good plan for a permanent repair.

Appreciate any advice on how to proceed & any precautions to take to protect the rest of the stuff in that compartment. 

Thanks

Pete P. 
Harborcreek, Penna. 

 

Our you form over function, or function over form?
I was in the right place at the right time and got a big oil tank and 2 valve control unit from a IH TD 14 loader. Very low use because the other IH stuff gave to much trouble. This made it possible to add a tilt cylinder to blade. It is hard to find 50 GPM control valves and pumps at good prices which is the needed volume to make the blade function well. It tried a 30 GPM pump and control way to slow with the original Cat rams.

The Cat tank is a casting so not the most easy thing to weld. But since I think the technical library here has parts book you can see what your taking apart before "let pieces fly away" in the shop. Or maybe use epoxy glue like was don't on a grader differential that was discussed here not long ago.

I'd be on the look out for a good used #46 tank. Got to be a few of them around as they are certainly not rare.

as was mentioned by another you could coat the entire inside with glyptal epoxy sealer paint. as was used on hanna the grader.
one problem that mightent work as the unit heats up the crack may expand.

cast is funny to weld and no two castings weld the same so what has probably happend is 1 they used the wrong welding alloy and it didnt bond and cracked.
2 they didnt prep it properly 3 simply bad technique.

my thinking is as OM has suggested get another tank or a whole unit and make one out of two. as painting or welding will require disassembly so you can properly clean and sweat the oil out of the casting.

if you decide to re weld it grind all the old weld away vee the crack and re do it with bronze gas welding alloy lower temp than arc welding so less stress and less likely to crack and remember get it hot first so bury it in hot coals or put it in a bbq to heat up. the best thing is take it to a engine shop and get them to weld it as they have the apropriate ovens and cleaning bath to do it properly.