C-161 w/Sundstrand Won't Move

[can whlvr 993]

they say that the intake isnt filtered so as to not starve the pump if a clogged filter is there,thats why theres a screen filter,its nla from toro,but a good sundstrand shop that rebuilds pumps can still get some parts,not everything though,when i had mine done i got a good cash deal from a very reputable hydrolic pump rebuild shop,they do excavators,dozers,skidsteers,etc,it cost me something around 500,but for me that was money well spent as its on my c160,and i want it strong and reliable,i know its alot but up here no parts guys so a used is hard to get,so i rebuilt her and never loooked back

[tommyg 152]

You're lucky the strainer didn't get sucked into the gears like mine. Once I located a "new" one, the end pieces were not intact by any means. I used JB Weld and made sure I worked it into the nooks and crannies of the screen to make sure it held tight. So far so good.

[mattd860 162]

I'm seeing a missing piece to the screen. I don't have the magnet anywhere. Maybe it is still inside the case somewhere but it is definitely not attached to the end piece of the screen. Maybe it got sucked up inside the pump body???

[tommyg 152]

It's possible, I suppose. But it's likely that it just attached itself to the inside of the transmission somewhere. After all, it is a magnet. That's where I found mine.

[mattd860 162]

Ok I have lapped the brass valve plate from the main pump but there are 3 grooves that run around the perimeter of the plate between the elongated holes. These grooves are fairly deep and they are uniform all the way around. Are these supposed to be here or do I need to lap the plate enough to diminish the grooves? NOTE: the same groves do not appear on the cylinder block and the cylinder block appears smooth.

The valve plate on the motor seems nice and smooth and it doesn't have these grooves at all.

I also tipped the valve body on end and a ton of black sludge came dribbling out of one of the holes presumably behind the charge pump. I didn't actually see it come out of one of the holes but as I was turning the unit over, I noticed a puddle of sludge on my bench and since my bench is clean it definitely came from the unit. Maybe this clogged something preventing oil from circulating??

I'm still baffled at the fact that if I moved the motion control lever all the way forward and then pushed the tractor forwards, the hydro would engage and I could drive the tractor like normal (until I moved the lever back to neutral).

[coldone 35]

No the grooves arent supposed to be there. I dont know how bad that will affect the pump, you should get some performance back but it wont be 100%. The minimum suggested thickness for the valve plate is 0.149 inches, so if you have some metal left I would see if I could get them gone. Grab a few cans of brake cleaner and use that to see if you can get the sludge out.

You may want to give LJ fluid power a call and price a new valve plate.

[mattd860 162]

Right now the plate is 0.155 so I can remove some more material.

[mattd860 162]

I did call LG Fluid Power and they have all the parts I need except a new strainer screen. The Valve Plate will cost $150 and the charge pump rebuild kit will cost $250. They also think that the reason why the transmission stopped working except when the tractor pushed forwards is because the spring behind the motor cylinder block has become loose or broken entirely.

In the interim, before I go spending any money, I will be inspecting the spring and clip under the motor cylinder by removing it entirely. If i do need to replace it, I will be purchasing the spring from LJ and make my own gaskets just to make sure it works again. If it does, I will probably tear it back down to rebuild the charge pump and install the proper gaskets.

[tommyg 152]

Might be worth the $150 for the valve plate. Those grooves look really deep. I'm not sure you'll be able to remove enough material and still keep it within tolerances.

[coldone 35]

I must have misunderstood LJ on the price of the valve plates.

[mattd860 162]

I gave LG a call and they said the reason why my transmission would work if I pushed it forwards was because the spring or retaining clip inside the motor cylinder block was broken.

So I took the motor cylinder block off and examined the spring and internals. The spiroloc retaining ring was definitely destroyed prior to even removing it. I saw it hanging out of the bottom of the cylinder block before I even removed it. When I removed the block, the retaining ring as all mangled. Also, the washer under the spring was all bent but I think that happened when I pressed out the shaft from the block.

Anyways - LJ is going to send me a new retaining ring, washer, and the other parts as well as a complete gasket kit.

Coldone - the valve plate is actually $56 dollars. The guy that told me $150 the other day didn't know what he was talking about.

[coldone 35]

Good to know one the price. Yea LJ is the one to talk to. I dont know if he is the only one there that does the WH drive but he is the one that I have to ask for to get the correct parts.

I blew the spirolock, retaining clip and washer in my spare motor when I was trying to rebuild it. I think its the 2nd vid that I made that shows how to install them.

[mattd860 162]

Charlie works for LJ and he is also very knowledgeable. But it was some other guy that gave me the wrong price. Both Charlie and LJ have helped me out immensely. But so have your videos!!!! I didn't even know you made them and they really cleared up my confusion from the manual instructions which are very vague in my opinion.

I feel a lot more confident about rebuilding this now but I made a major mistake that may have killed this whole rebuild. I marked out the pistons to the cylinder block but somehow the mark I made on the cylinder block has disappeared. I made the mark using magic marker but the surface must have been a little oily so it must have rubbed off. I'm going to have to 'wing it' when I put the pistons back into the block at this point - odds are 1 in 9 I will get it right. The biggest problem is that after I rebuild everything, if it still doesn't work I'm not going to know if it's because of the original problem or the motor pistons in the wrong bores.

[pfrederi 17,887]

I wouldn't obsess over that the piston issue to much. As long as they aren't worn too badly and all fit with about the same degree of tightness.

Have you taken a closer look at the charge pump that would be a bigger concern for me.

Edited December 1, 2012 by pfrederi

[can whlvr 993]

ya when i tried to repair my pump i didnt keep the pistons in their orig bores,when the shop repaired it it wasnt a big deal

[mattd860 162]

Just a quick update. The parts will arrive in mail tomorrow. For now, I just ordered a new seal kit and the lock ring, washer, and spiroloc ring for the motor cylinder block. If that doesn't fix it then I will order a new charge pump gerotor set and valve plate.

I further disassembled everything tonight and I did find some small metal bits in some of the channels. I suspect that they might be from the intake screen magnet that I have yet to locate.

I also cannot remove the forward and reverse check valve plugs. I hate that Sundstrand decided to use flat-head screw driver slots instead of allen screws or something better.

[coldone 35]

Glad to see you making progress! I havent had a chance to sit down and explore the pistons and bores but in talking with some Hydro repair people it shouldnt be too big of a problem. Just make sure that they all fit rather snuggly.

For the slotted caps, i ground down a paddle style drill bit to where it would just fit the hole. It worked for me and I think there is a pic of it somewhere on here.

I would also suggest that you take the time to attempt to flush out the transaxle. It would suck to go through all of this just to have left a few metal bits that would get pickup later. I have no idea how to accomplish the flushing without taking the transaxle apart.

[coldone 35]

found it.

[mattd860 162]

Glad to see you making progress! I havent had a chance to sit down and explore the pistons and bores but in talking with some Hydro repair people it shouldnt be too big of a problem. Just make sure that they all fit rather snuggly.

For the slotted caps, i ground down a paddle style drill bit to where it would just fit the hole. It worked for me and I think there is a pic of it somewhere on here.

I would also suggest that you take the time to attempt to flush out the transaxle. It would suck to go through all of this just to have left a few metal bits that would get pickup later. I have no idea how to accomplish the flushing without taking the transaxle apart.

Thanks, that is a great idea and i'll give it a try. Since I fixed the intake screen I don't really have to worry about flushing the transaxle unless the screen breaks again. I'm more worried about other metal bits that may be stuck in areas that I cannot clean out. i'm also a little confused about how the metal made it's way past the charge pump gerotor without totally destroying it.

[pfrederi 17,887]

To remove the forward and reverse vlaves you need to go to get a drag link socket. (Looks like a big flat blade screwdriver bit). use that on your impact driver and they will come out

Drag link

Hand impact driver

[mattd860 162]

I just got them both out using coldone's method. I found some more metal chunks inside the motor.

I wonder if one of the metal bits got wedged between the gerotor set therefore causing it to stop spinning which resulted in a lack of charge pressure??? We'll see after I get everything back together in the hours/days to come.

[mattd860 162]

Ok I got everything back together and installed on the tractor and it works!!!! Again, all I did was relace the seals and the guts of the motor cylinder block. Thanks everyone for you help!!!!!

[WheelHorseSteve 56]

Ok I got everything back together and installed on the tractor and it works!!!! Again, all I did was relace the seals and the guts of the motor cylinder block. Thanks everyone for you help!!!!!

That's great, Matt! (Congratulations on the repair!) Given the extremely similar symptoms seen on my C-160 Sundstrand transmission over a year ago, I might just crack it open this Winter and take a closer look. Your pictures and experiences here will surely help others as they dig into their hydrostatic problems.

[mattd860 162]

Thanks. It's also very fulfilling to actually know how these types of transmissions work. It was always a big mystery to me lol.

[coldone 35]

I just love happy endings

I am glad you took the time to tackle this problem and add to the knowledge base. I was very intimidated also when I tore into mine but I figured it was already broke so why not.

Do you think it feels just as strong as before? Do you seem to have the same or beter performance out of it? I know mine will now pull the front tires off the ground and will dig a hole to china if a put it up against an stump. The top speed has increased and also there is no noticable change of speed when going from down hill to up hill.