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Case 646

5361 Views 13 Replies 6 Participants Last post by  marlboro180
I purchased a case 646 yesterday that's in need of a little TLC. The gentleman that I purchased the tractor from bought it form the original owner with a seized ONAN CCKA. He put $2500 into getting the engine rebuilt but after installing the rebuilt CCKA on he ran into another snag. The fully rebuilt engine barely has 10 hours on it.

The hydraulic system works, but after about 1/2 hr of operation the tractor can barely move. He claims that he replaced the hydrualic oil with new 5W20 when the engine was replaced and that the previous owner had used the same. When we loaded it on a trailer to move it to it's new home we had to push the tractor to help it up the ramp..

I just got the tractor last night and haven't had much time to go over it. Posts on different threads show that the the oil is the first thing to look at with hydraulic issues. If what the previous owner claim is true and that tractor does have 5W20 in the system, would going to a 10W or 15W40 oil make that much of a difference? It's fairly cold in Manitoba right now, do I want to go to heavy?
Next many have said that the Banana Plate/Control plate is the next area to look at. I looked at it today and everything seemed to be functioning fine. Could anyone give me a better idea of what I'm looking for here, how much play if anything would be acceptable, how much should i see the linkages move, etc.....?

And if I need to do a system pressure test is there anything "tricks of the trade" I should be looking for.

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15W40 is the way to go, though in real cold the machine should perform pretty well before warmed up. Once warm, the 5W20 will simply not perform well.

The linkage should have minimal looseness in it, though all old ones will have some. Bottom line, to perform well, in either direction the linkage must move the valve spool to full travel. A common failure is the forward slot being badly worn, such that much of the pedal travel is taken up before the spool ever starts to move.

These 2 put together could result in truly poor performance ... I would change the oil first ...

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I have about 5/8 to 1/2 movemonet on the spool valve.
Is that about right?
About 1/2 to 5/8" travel either way seems close ... don't have one in front of me.

It's hard to describe in words, but if you have lost motion on the pedal, chances are it is not pushing the valve fully in. To some extent you can manipulate it with your hand or a tool, to see if more is available.

Drop me an eMail and I can send back an illustration of the plate which helps describe the primary wear point.

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The travel controls in these loaders are prone to wear/adjustment issues.

Like Brian said, your spool movement sounds about right. The spool only moves about 1" full forward - to full reverse, so any misadjustment/wear can create issues. Not serious, but annoying.

After you have checked everything out, keep in mind that at one point the bannana plate was NLA. However, Brian worked the factory and a kit was developed to completely upgrade the travel control to the later 6000/7000 linkage. As I recall, around $200, and well worth the investment.
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How much can you wiggle the pedal up and down before the valve starts to move?

You may also need a new pump
I was able to take a quick look at it and it could have excessive play in the banana plate. Going to take it out later today and try to either adjust the travel or jimmy rig it so I can get more movement in the spool. I see if it improves anything.

How would you determine if the pump is Bad Order? Any simple ways of checking.
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Have you tried the tree test? Push against a tree with the bucket, the rear wheels should spin in lo, and lug the motor down in Hi. Prolly at 2/3 throttle should do it.

Attached are a couple pics of a worn out plate- hopefully yours looks better than my old one. No amount of adjusting was going to get it to actuate properly to move at full forward.


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Tree tested failed.

I Didn't change the oil yet but with the oil still cold I took the tractor out and didn't have enought to spin the tires, but it didn't bog the engine down in any way.

I took a close look at the banana plate and noticed that the C17553 pedal control rod is bent in a lazy S shape. Is that standard.

I have pictures which I will post soon.
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Pin should be straight ... reply with details is in your eMail ... in stock for immediate shipment ...

Tree tested failed. .
Did it fail in reverse too?
I tightened a few of the linkages and tried again. Could spin the tires in forward, but not in reverse. Brian thinks the banana plate is a home built, and the peddle control rod was severely bent, seems intentional. Planning to change them, and I'll update after that.
Sounds good, that'll give you time to swap that oil out.:fing32:
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