Case 646 compact loader (Questions)

I bought a 1972 Case 646. It didn't have an engine when I bought it. Other owner said it had the CCKA 16.5 onan in it. Engine was bad an the cost too rebuild the old one he lost interest in it. I'm slowly getting it back togther. I had another onan engine from a JD 420 with the P220 and I just got it installed.
Problems I'm having is the hydraulic pump not having enought pressure for the Hydraulic motor on rearend. Gets worse as it oil warms up. I checked the pressure at one time it was 1900 psi cold at full throttle. Should be around 4000 psi.
The pump thats on it I believe the origanal pump yet with the 3/4 shaft dia. My question did the onan ccka 16.5 engine have a clockwise rotation or counter clockwise rotation? Looking at the shaft side on pump like would a face of a clock the arrow in the back of the pump shows the pump rotation going counter-clockwise.
Im going to buy a new hydraulic pump but having put in this P220 onan engine which I think has the clockwise crank rotation but doing need to buy the pump with the clockwise rotation or counter-clockwise rotation.

I looked up some pumps on some websites I found one on McMaster Carr Pt # 6296K27. On Northern-Tool Pt # WP09A1B100R03BA102N.

The pump I have maybe worn out or maybe the rotation going wrong direction? Any help on this is sure welcome too me!

Mike
 
The 646's came with a 16.5 HP ONAN CCKA engine. All of these engines rotate in the same direction. The first thing you need to do is to remove all of the oil that is currently in the hydraulic system and then install fresh 15W40 Shell Rotella T motor oil. This is a messy job because in order to do it right, you have to remove the hydraulic hoses from all of the cylinders. Then disconnect the rod end of the cylinder so you can pull that rod out to full extension and push it all the way back in again. Do this a couple of times. If the mid-lift cylinder is still under the tractor, then you must empty it too as well as the cylinder on the 3 point hitch, if so equipped. You can use a turkey baster to suck the oil out of the reservoir tank.

All too often, people put hydraulic fluid into these tractors because they don't know any better. As soon as that fluid warms up, the tractor has no drive power because the oil viscosity is wrong. I suggest that you slow down and take this one step at a time. And the first step is to make sure you have the correct oil everywhere in the hydraulic system. Once that is done, then it is possible to conduct pressure testing on the system. Normally, the relief setting is around 2300 PSI. I don't know where you got 4000 PSI but that is wrong. I suggest that you hold off buying a pump until it is determined that the existing pump is worn out.
 
Tom,
I've had all three cylinders apart to put new oil seal kits in. I think the loader tractor has set for a few years even before the other owner had it. All the oil seals/O'rings on all 3 cylinders was cracked or dry rotted. I Also found the travel valve & loader contol valve o'rings hard an worn. Also changed seals on 3 pt.

I used the 15W40 Shell rotellat oil too refill the unit. In fact I done it twice in the past few months. I have noticed the amount of shaveings and the color of the oil looking silverish color when I drained it.

I also changed the Hydraulic motor on the tractor too. The one on it I torn down had some wear but noticed the big wasker that has the small O'ring was missing. I put a different motor on that I new was good and it did seem to make a big diffence in handleing when shifting too forward and reverse and also had more torque.

Going back too the hydraulic ground drive valve I've adjusted the relief valve using a 4000 psi gauge setting to get it near 2000 psi but everytime it only biuld up 1900 psi tops. If you run the tractor around for a few minutes to warm it up the pressure drops more even at full throttle.
I even turn the pressure valve spring completly into till it stop on valve seat. Still have no torque I think it needs to meet the demand to push loose dirt into the bucket. In fact it won't even try too spin a wheel.

I do have the pump off yet but haven't torn it down yet. i see the seal on it wet and it's probably hard and worn also. I'm running out of answers on whats going on with the ground travel not building up torque to even push dirt.

My other question is when hooking up the hydraulic motor to the pto shaft side of the engine w/the couplers the direct of both shafts are should run clockwise sitting in the seat or counter clockwise? The arrow on the back of the hydraulic motor goes counterclockwise rotation looking at it from the back of the pump sitting in the seat. I don't know which way too look at for rotation from front or back?

As where I got the 4000 psi on a pump was from a forum on internet some where? thats how I came up with McMaster Carr Pt #. It's been a while since I seen it I'll try too see if I can find the discussion on it.

Right now I'm going to dis-mantal the pump and ck for wear ect. I'm hitting the bottom of the barrel so too speak on what the cause can be. Being there shavings and discolor in the oil something wearing out some wheres. I'm also may try hooking up some kind of a filtering on the hydraulic return side.

Thanks you guys for your time an help, i'll post again on here if I come up with something.
Mike
 
My bet is that you will find the pump housing worn and oil is bypassing the gears. The engine turns counter clockwise as viewed from the seat. The pump must turn the same way. But, it will be termed a clockwise pump as that is viewed from the shaft end, not the back.

BTW, with a very few exceptions, all engines rotate the same direction. I've never encountered a outdoor power equipment engine that did not rotate the same way.
 
OK..... if you are satisfied that the hydraulic system is full of 15W40, then based upon your other findings, I would agree that replacing the pump is the next logical step. The pump you mentioned meets the OEM specs.

Rotation is a tricky subject. Here's why. It is all about your point of view. When deciding if an engine or electric motor is rotating CW or CCW, you must stare at the end of the output shaft. The confusion comes when you must decide on the rotation of the pump. The exact same requirement is in effect. You must stare at the end of the input shaft of the pump. It is the point of view that is confusing because one is the opposite of the other. If the engine rotation is CW, then the pump which is direct-coupled to that output shaft must be CCW. If the engine rotation is CCW, then a CW pump must be used.

If you stare at the output shaft end of your engine, I believe you will find that it rotates CCW. Therefore... you need a CW pump.


IF the wrong rotation of pump is installed, then it will not pump oil effectively enough to allow the tractor to travel or to operate the loader. You would also not see 1900 PSI on the gauge. Don't waste your time looking up that thread from another site. I see erroneous information all the time at sites. Installing a filter on the return side is up to you but what is far more beneficial is to drain the reservoir every 100 hours of operation and install new oil. If you install the new pump, then before you start the engine, back the relief off several turns. Then with your pressure gauge connected to the test port of the TRAVEL VALVE, see how much pressure can be developed with the RANGE LEVER in High Range, the engine at wide open and the Travel Lever pushed forward while the bucket is up against something that will not move. Slowly screw in the relief while watching the gauge. When you reach 2350 PSI, stop.
 
Ok, this is what I found so far dismantling the pump. The pump looks to me to be a pump from a 644? Looking at a parts breakdown between the 644 & 646 it looks like the same pump as the 644's. I'm not sure what the pressure ranges on 2 are if any?

Kencombs your are right taking a guess on the wear plate to be badly worn I run a indicator base w/indicator on flat surface across the steps in beded in the brass on wear plate coming up with .008 to 0.10 step. Also on the rear cover it's worn so uneven w/deep guruves in the aluminium part of the plate. Also seen egg-shaped bear or bushings. One time or another it must of had water in system an froze over the winter setting. Wear plat has a hair line crack between the 2 bushings.

I think I will order a new pump. lot of work trying to get the old pump out! Not unless your a pigme or have arms an hands like a 4 year old Ha Ha. Me I'm getting old all my limbs are like tree branchs. Now I will go back an reveiw the two shafts on the directions there going. I think what got me confused on the rotation was the arrow on the back of the old hydraulic pump cover. facing the back cover the arrow going counter-clockwise (left) rotation.

***So if I'm correct I need to order a counterclockwise rotation pump correct?***
Mike
 
Looking AT the shaft end on the pump the arrow on the back pointing counter clockwise rotation, then if you turn the back side of pump looking at the arrow from the backside of pump it shows it going ccw.
I'll try taking some pictures of this pump I have. If the pump shaft an crankshaft are connected together looking down at both shafts the shaft from engine should turn clockwise when it's running.
Whats confusing too me is the arrow on back side of pump shows it turning counter clockwise still looking at it from shaft side on pump. So the drive gear on pump is turning CW then driven gear turns CCW.
I guess it's on how your looking at it and the way your looking at it. Maybe the arrow on the back on the pump doesn't mean any as far as ordering a new pump? I'll try taking some pictures when I get back out to the shop.
Mike
 
(quoted from post at 17:20:20 08/07/15) Problems I'm having is the hydraulic pump not having enought pressure for the Hydraulic motor on rearend. Gets worse as it oil warms up. I checked the pressure at one time it was 1900 psi cold at full throttle. Should be around 4000 psi.

Where and how were you measuring the pressure. I have a 646BH and have my relief set at 1900 psi. It is a lot heavier than the regular loader, but I have near full power. (I know how rare the backhoe transaxle is and do not want to damage it.) I can climb reasonable hills in high and can overflow the bucket with any material in low. When I got it my pump was also shot but it would peek at 1200 and drop to 800 or less psi when warm with Rotella. But from your tear down of the pump it sounds bad. Mine didn't even look that bad when I inspected it but it is a knock off so the quality was low to begin with. Good luck.
 

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