CASE 990 Hydraulic Leak

[kyle g]

Hi There,

1965/66 DB/CASE 990 SN 482958 (I think it's a very early model Selectamatic) that pulls great and has been reliable for me for the last 6 years. I've had this bad leak on the left side of the seat that seems to pop up reliably when I'm cruising on roads between fields. It happens reliably when the wheels are turning fast, but I think leaks also at working RPMs in the field when I'm pulling, but not always. Photo of the RH and LH side of the seat for identification (because I know this era had lots of weird differences between years), and you can see in the LH photo the leak. It does have an auxiliary raise/lower handle on the LH side. I'm not sure if the knobs on the lower LH side have anything to do with a pressure relief or something like that. I'd rather not split the tractor right now but would be nice to find a solution... Thanks for any tips

 

[RGMartin]

Lots of non-factory plumbing going on there. Hose it off with solvent and start looking for the source of the leak, then tear into it.

 

[Jim.ME]

Welcome to the Forums.

X2 on RGMartin's post. Clean it good, get rid of any the oil and crud then start looking for where it is coming from. That is going to take hands on work to track it back to the source.

 

[want@1070]

If you can, replace shift lever boot , may alleviate future problems, Thanks for pic and
Keeping a D B going.

 

[kyle g]

Thanks for the thoughts, yes I replace the shifter boots about annually and have a bit better clamp system this time around so hopefully they will last better. Just did a full engine and transmission oil overhaul so everything is a bit happier.

The leak is coming out of the body, where it splits, not out of any external plumbing. So it could be the gasket there, but seeing as it seems to happen under higher engine revs or wheel revs, I wasn't sure if there was some sort of pressure relief system that might not be working, and so it blows out of the seam. There are the three knobs below the left side of the seat that I've never completely understood (circled in red), and then the selectamatic 3-position knob that I sort of understand. I really just use the hydraulics for the 3 point and aux raise/lower, not for any of the selectamatic 'features'. Any more thoughts from those who know how these controls work? These model years were funny because DB changed a lot from 65-70, where different years have different systems, before they standardized their 1970s models. And then of course there's after-market additions, but these knobs and dials are stock for sure. Thanks

 

[RGMartin]

That is the three way valve. The gaskets should just be regular rubber O-rings, available at any hardware or auto parts store. It just bolts onto the casting. Nothing difficult or complicated there.

 

[Jim.ME]

You saying it leaks out the seam at higher road speeds and higher rpms in the field, indicates to me there is more oil being thrown around in there with the increased rpm of gears and shafts and a bad gasket at the split is allowing oil to escape.

 

[kyle g]

Thanks, ok well I guess you're confirming my suspicion of just a bad gasket at the main split, so I guess this one will roll as a leak for awhile longer!
Will someone please explain the three way valve to me? I've never understood it, and haven't seen it in a manual. It's dear drivers left ankle, with those two black knobs on top (circled above) and one selector on the bottom that looks like it used to have a knob. I never really understood how it works and how it relates to the 3-position selector on the right side. I only operate the 3 point hitch, and then (separately) aux raise lower for things like my disc and combine attached to the drawbar. Thanks

 

[want@1070]

Kyle, to rotate the selector indicator pointer, i move the white 3 point lever way back, and force it
past the spring loaded part, then the pointer moves easily, My Dad broke the pointer on our "995" .
I leave it in the center for all our uses. .hope this helps !

 

[Fritz Maurer]

Plenty of water in that oil.

 

[kyle g]

Yeah changed all the oil out and fixed the boots so good now.
@want@1070 thanks, I think you're talking about the selectamatic dial on the right? The Height/depth/external TCU. The lever needs to be pulled rearward like you said to select the setting. I leave it on the external/TCU because I don't use anything with the 3 point that needs draft.

But what about the 2 black knobs on the left side by the driver's ankle? and there's one underneath too.
It seems the black knobs adjust flow for something and then the selector underneath I have written from somewhere L (Loader)/Neutral/H (hitch). But I don't really know what that applies to or where I should have it set. Like I said I use aux hydraulic for raise/lower on a number of implements like my discs and combine head. I don't have a front loader on it. I feel like if my settings here are incorrect, it could be blocking flow and causing it to leak out of that split maybe. At the very least it would be great to know what settings I should have it on. Thanks

 

[joestewart]

Open up the following link and scroll to page 22. Read the explanation and see if that helps. I own several DBs but none of them have that particular valve

David Brown 770 Instruction Book

 

[kyle g]

Thanks Joe, this is gold. I'll have to make sure the correct valves are open for each operation. I might have the wrong thing closed at the wrong time and so it's deadheading against the case and seeping out. Was running the old combine behind it all day yesterday at full RPM and no seepage, so it also might just be tied to wheel rpm when I drive it on the road.