Case 1840 Hydrostatic Drive Issue Please HELP

I thought the tow valves got screwed IN to disable , OUT to operate??? Am I mis-remembering this important fact???

Well in my world that pump is shot...most oil would be going straight back to case...which goes right back to tank..if you can feel anything at all on plates it will go straight to case at system pressure...plus your charge pump would never keep up with that much wear....there are actually 3 circuits on a hydro pump....charge pressure ...system pressure. . And loop cooling....the sauer pumps have an internal hot oil shuttle for cooling...and the motors will too...but those pumps are so bad most of your charge pressure was going to case for sure.

Apetad, I’m no expert by any means as you can probably tell by my post, ha ha, but the owners manual states to back out valve no more than 2 turns for bypass and tighten for normal operation. The danfoss manual says same thing except no more than 3 turns.

I wish it had been that easy. You had me thinking for a minute.

rondig, now that makes complete since, but how did the groves get there to begin with if that is the case? My first thought is maybe air initially in the system creating cavitation, which caused the wear, in turn lead to, well you know.
My second thought, maybe contamination created wear, which caused the cavitation. But again no wear to motors......
My 3rd thought, I’m going back to when you said something about not having oil in it. When I got the pumps back in the machine and plumbed, I pulled the charge pump plug and filled the pumps there. Was that enough oil? Should I have done more? The pump had never been apart

So rereading the thread, rondig said, “If the wheels turn with the counter balance valves released and the motors are good then there was not enough oil in the loop.”
So I’m thinking I should have filled the pump as I did, manually turn the tires, refill pump, and so on until I get resistance. ??????

Am I on to something or no?
Are counter balance valves the same as relief valves?

I have fitted more than a few of reconditioned/exchange tandem pump assemblies to Case skid steers.

With the hydraulic tank full of oil & wheels off the ground, I've never done more than start the engine & let them idle for a minute or two while looking for any leaks & then slowly work the controls to full fwd & rev - & never had any issue with cavitation or operation of the machine.

The 1800 series Case machines have a very good supply of oil flow from the tank to the tandem pumps.

PS - I'm not familiar with the term counter balance valves (but, I come from the land downunder where Australian lingo is used) as far as the Case hydrostatic system goes ..... I'll go out on a limb & say the service manual for the 1840 doesn't mention them either.

Wheels off the ground is the key...you never sent the tandems to system pressure to get the wheels turning...or you can fill the pump case...any piston pump...danfoss..rexroth....any brand wants the case full before start...
The damage in your pictures is cavitation....if the pump was dumping to case....most of the crap will be in return filter....saving the motors..i am wondering if the charge pressure relief in the pump didnt go first..or if charge pressure was released somewhere...looking at pistons and wear plate or could have been contamination....but when you showed picture of cradle...that was the key to cavitation....cradle scored that bad pretty much only occurs when lack of charge pressure...therefore cavitation.

Well I got some news. I decided to cut the oil filter to see what may be inside. Not good. What appears to be everything from rust, to sand, to paint chips (silver, the color I painted it and yellow, the original color)!!!!!

I will attach photos.

Its obvious that this somehow got in there while I had the machine apart.

At initial start up, I let machine idle for roughly 2-4minutes, moved the machine in reverse and then forward. When doing this it had a lot of power back and forth, but would not steer. As I moved around the garage for about 2mins, it was loosing power and has had consistent power ever since.

My theory, (I could be completely wrong) or maybe just a guess, this debris was in the pump, running at idle (at first start up) it wore the pumps. When I moved the machine the pumps were wore so fluid went directly to case drain. Never made it to motors......

Your thoughts????

Man that sucks....yep pistons and wear plate got that crap and the cradle failed for no to little charge pressure....oh man your control circuit is pre filter....so you will want to check that too.

So I got the pumps back together and sitting aside until I get motors figured out.
I ordered 2 rebuild kits from case for the drive motors. Figured I would go through them and clean and replace seals just to be on the safe side.
My problem is that all of the seals are not in the kit. There are 2
o-rings, roughly 4” od, 3.75” id that I do not have. Am I over looking something? In my parts manual the seal kit is all that I see

I can't recall having a problem with the kits, but I have not used one for quite some time...
Don't you you love it when you pay top dollar for a 'genuine' seal kit & it doesn't do what it is supposed to......

I would look get the part numbers for the missing seals & giving the dealer a call, obviously this is something CNH needs to know about.

I spoke with dealer this morning. They sent me the wrong seal kits. Apparently there is more than one for this machine

Got the other set of motor seals and they were correct.

Installed everything today. Just got back from a test drive and everything works perfect!!!!!!!!!!!
Now let’s just hope it holds up!

I want to thank everyone on here for the assistance. I could have never pulled this off without you. I would have never been confident enough to pull this off without this site and the people on it.

I will keep you posted on how it holds up. I’m going to be nervous for the first few hours. Remember not only are my hand all over the hydrostatics, but also the engine has about 20 minutes of run time.

I would like to mention that I filled the pump with oil in all ports and I believe this is unnecessary (as “airman” said). Each port holds less than a cap full. Gravity from the tank supplies the pump.

If this system holds up, the way I did it can save a lot of money. I pretty much lapped all parts in motors and pumps and resealed everything. It cost me less than $1000 vs the
+/-$5000 for rebuilt pumps and motors. Probably not an efficient way for someone making money with a machine, but for someone like me that is just using it around the house and has time to spare. This is the way to go. (Again if it holds up, fingers crossed). I will update in a few hours of run time.
Thanks again!!!!

WooHoo! Congratulations on a job well done!

You don t have to fill every port...just the case drain. I am glad to hear it is working for you.

I almost forgot to mention,
I did not install new chargepump. It was very expensive and easy enough to change out without pulling pump. Just split pump in machine if needed. I am getting 450 charge pressure at wide open throttle and about 430 with both levers fully engaged

UPDATE.....
Just hit 10hours of run time. Like mentioned in earlier post, I only use this around my house so it doesn’t get much use.
I hope I’m not speaking too soon, but everything is working as good as the day it was put back together.

Thanks again everyone

UPDATE: 72 hours. Still running strong