L555 Please save me from divorce!

[antfarmer2]

OK. Found a 1/4" to 1/8 adapter today. Plumbed in the gauge and fired it up. Gauge read 140 psi at full throttle. It dropped down to about 130 psi when I stroked the levers a little. That isn't quite the 150 - 190 psi that the service manual calls for but it doesn't seem low enough to cause the problems that I'm having. Unless someone tells me different I will move on to the pump case draining measurement on Wednesday. I just can't imagine what the hydro shop could has done to these pumps. It is not one bit better than it was before the rebuild. I know it's gonna be a fight. No one ever wants to admit when they've screwed up. These guys seemed very confident and they've been in business for a long time. Mostly do combine hydrostats and other AG equipment but they also do construction hydrostats and seem to know what they're doing -- been in business since 1986. Any other tips? I'm not looking forward to this experience.

Does it have a drive belt from the motor to the pump?...... did it get greasy or is it loose?

 

[palmtree]

Does it have a drive belt from the motor to the pump?...... did it get greasy or is it loose?

No drive belt that I know of. There is a shaft that runs through both hydrostat pumps and into the gear pump at the front. The splines all looked good when I installed the pumps. I'm still a little confused on how to measure the pump case drain flow. I understand where to attach the hose and all. I just don't understand how I can get a measurement with the pumps under a load when the machine is up on jack stands. Wouldn't a load make a big difference in case drain volume/min? Thanks again to all who have tried to help me.

 

[jerry]

No drive belt that I know of. There is a shaft that runs through both hydrostat pumps and into the gear pump at the front. The splines all looked good when I installed the pumps. I'm still a little confused on how to measure the pump case drain flow. I understand where to attach the hose and all. I just don't understand how I can get a measurement with the pumps under a load when the machine is up on jack stands. Wouldn't a load make a big difference in case drain volume/min? Thanks again to all who have tried to help me.

The drive coupling from engine to pumps is in good shape? No chance It it slipping is there? I only have redone one set of pumps and that was on a bobcat but they were surprisingly simple as long as all the parts are kept in order and clean. Did the rebuilders say just exactly what they did? I don't have much faith in people who quote years of experience because I have seen too many still doing things wrong after 20-30 years of experience. Sorry I can be of no help although it seems case drain amount would change very little from loaded to running on jackstands since where it is bypassing at 150psi isn't going to let much more through at 1000.

 

[palmtree]

The drive coupling from engine to pumps is in good shape? No chance It it slipping is there? I only have redone one set of pumps and that was on a bobcat but they were surprisingly simple as long as all the parts are kept in order and clean. Did the rebuilders say just exactly what they did? I don't have much faith in people who quote years of experience because I have seen too many still doing things wrong after 20-30 years of experience. Sorry I can be of no help although it seems case drain amount would change very little from loaded to running on jackstands since where it is bypassing at 150psi isn't going to let much more through at 1000.

Well they just said rebuilt to OEM specs. They have a test bench which I assume they put to use before they sent them back to me. I sent them both pumps and both motors and a check for $3000! What makes these things so expensive to rebuild if they are simple? I had another quote for $8000! Give me a break. A 1993 L555 in perfect, like new condition isn't worth that or maybe just barely that. I feel there just may be something else I'm missing. If it's the pumps or motors then it is as if they didn't do anything but clean them and send them back to me. How would I test the drive coupling? Is there a way to do that without removing the pumps again? Would a slipping drive coupling explain my symptoms. Thanks, Brett

 

[antfarmer2]

Well they just said rebuilt to OEM specs. They have a test bench which I assume they put to use before they sent them back to me. I sent them both pumps and both motors and a check for $3000! What makes these things so expensive to rebuild if they are simple? I had another quote for $8000! Give me a break. A 1993 L555 in perfect, like new condition isn't worth that or maybe just barely that. I feel there just may be something else I'm missing. If it's the pumps or motors then it is as if they didn't do anything but clean them and send them back to me. How would I test the drive coupling? Is there a way to do that without removing the pumps again? Would a slipping drive coupling explain my symptoms. Thanks, Brett

That is what I was thinking something could be slipping from the engine to the pump but no belt......how did the drive coulping look when you pulled the pump

 

[palmtree]

That is what I was thinking something could be slipping from the engine to the pump but no belt......how did the drive coulping look when you pulled the pump

There was just a splined shaft coming out of the back of the rear pump that slid into a matching hole in the flywheel cover (or whatever it's called). The splines looked good and it was a nice smooth, tight fit. I guess if there is a flex plate or something it must be inside that cover?

 

[Mike10]

That is what I was thinking something could be slipping from the engine to the pump but no belt......how did the drive coulping look when you pulled the pump

If anything was slipping then the boom and bucket would also be affected since the hyd pump is at the end of the drive line. These things either work or they don't. You need the machine blocked off the ground so it does not take off on you when stroke the levers. By engaging the parking brake before stoking the lever you will build more pressure in the system which will make a leakage problem more obvious.

 

[palmtree]

If anything was slipping then the boom and bucket would also be affected since the hyd pump is at the end of the drive line. These things either work or they don't. You need the machine blocked off the ground so it does not take off on you when stroke the levers. By engaging the parking brake before stoking the lever you will build more pressure in the system which will make a leakage problem more obvious.

I see thanks. When I tested the charge pressure last night I stroked the levers with the parking brake applied. I didn't stroke them enough to bog the engine down because i was nervous since I didn't have it blocked off the ground. The hydrostat did start to whine a little and that made me nervous too. Ha! I'm a total rookie at this stuff. Am I right that a charge pressure of 140 psi at full throttle is not too bad? My wife says a guy shouldn't buy equipment like this if he doesn't know how to fix it or have the money to hire it fixed. She may be right but now I'm on a mission.

 

[antfarmer2]

I see thanks. When I tested the charge pressure last night I stroked the levers with the parking brake applied. I didn't stroke them enough to bog the engine down because i was nervous since I didn't have it blocked off the ground. The hydrostat did start to whine a little and that made me nervous too. Ha! I'm a total rookie at this stuff. Am I right that a charge pressure of 140 psi at full throttle is not too bad? My wife says a guy shouldn't buy equipment like this if he doesn't know how to fix it or have the money to hire it fixed. She may be right but now I'm on a mission.

You did change the hydro filters?

 

[palmtree]

You did change the hydro filters?

I wish that was it. It has new oil, new filters and I've cleaned the suction screen several times (even when it wasn't dirty).

 

[Mike10]

I wish that was it. It has new oil, new filters and I've cleaned the suction screen several times (even when it wasn't dirty).

When you have 140 psi is it still jerky?

 

[palmtree]

When you have 140 psi is it still jerky?

I'm not entirely sure. It moves fairly smooth if I go really slow. Gets really jerky under load like when turning. I can't see the gauge while I'm driving it.

 

[jerry]

When you have 140 psi is it still jerky?

If you can get along without the machine for awhile leave it sit and go fishing for a few days. You may have a lot of air in the oil and only time will clear it out. The bobcat I did was like that at first then due to other things it sat for a month, when I went back it worked perfectly because all the entrained air had risen out.

 

[palmtree]

If you can get along without the machine for awhile leave it sit and go fishing for a few days. You may have a lot of air in the oil and only time will clear it out. The bobcat I did was like that at first then due to other things it sat for a month, when I went back it worked perfectly because all the entrained air had risen out.

I've managed to get along without it for 42 years so I'm sure I could survive without it for a while. However, I do think it would be best to test the case drain flow first so I can contact the shop that rebuilt the transmission if it isn't up to spec. I will be checking the case drain flow today and I'll report back with my results. I'll be attempting this test by myself so we'll see how that goes. Wish me luck.

 

[palmtree]

I've managed to get along without it for 42 years so I'm sure I could survive without it for a while. However, I do think it would be best to test the case drain flow first so I can contact the shop that rebuilt the transmission if it isn't up to spec. I will be checking the case drain flow today and I'll report back with my results. I'll be attempting this test by myself so we'll see how that goes. Wish me luck.

Now what? I put the L555 back up on jack stands and applied the parking brake. Removed the case drain line from the pumps and attached a hose from the pumps to a 5 gallon bucket. Started it up and gave it full throttle. After running at full throttle for 3 minutes I only had around a quart in the bucket maybe a little more but definitely less than a half gallon. Then I stroked the levers a little one at a time. The left sounded worse than the right. The left made a growling sound and the right made more of a whine that is pretty similar to the sound my Grasshopper mower makes. The case drain flow didn't increase noticably when I stroked the levers. I guess this means the pumps are in pretty good shape huh. Is there a way to check the motors without removing them again? Is there anything else I could be missing? The oil did look like it had a lot of air in it. When I first bought the machine the oil looked pretty good (looked like oil) but the machine didn't run well (pretty much ran like it does now). I talked to a local (small town) hydraulic shop about it. He assured me they could diagnose if not repair it. I loaded it up and dropped it off at their shop. They started looking into the chain case first -- everything looke good in the final drive. Then they said it must be the motors or the pumps and they couldn't fix them or even test them beyond dead heading the lines. He gave me a number for a shop in Kansas City. So I talked to him and he said he has a testing bench but he doesn't like to put unknown parts on his bench with possible contaminents. He said he can usually see what's wrong by tearing them down and visually inspecting them. When I picked it up at the local shop it had been setting out in the rain for a couple days and they failed to seal the top chain case inspection panels (didn't even put the fasteners back in). When I got it home the oil was milky white. So they charged me $375 to tell me they could do nothing and they introduced water into the chaincases (and some other things that I won't bore you with). So I took the motors out (huge pain) and took them to the guy in KC.. He said there was not catastrophic damage but they were a little worn. He wanted to see the pumps. So I removed the pumps and took them to his shop. He tore them down and said about the same thing. No catastrophic damage but looked a little worn (the machine does have 3800 hours on it and who knows what kind of maintenence). He then proceeded to tell me that he recommended just replacing them because it would cost nearly as much to rebuild them. He quoted me $8000 to replace them. I told him I'd come pick them up. So I get there and everything was in a thousand pieces in four big buckets (one for each pump and one for eash motor). Then I found these guys who said they could rebuild the pumps for $1600 and the motors for $650 each. It's a lot of money but I was in a pretty big pinch. I'm telling all this because I'm wondering if I should change the oil again. I drained everything down really well and cleaned the chain cases really well but I'm sure there is still some water in the oil. It isn't milky white but it is kinda yellow and foamy looking. The thing is that I don't want to change the oil again ($130) if I'm just gonna end up draining it again to remove the motors again. Sorry for such a long post. Thanks again for all of the help I have received.

 

[palmtree]

When you have 140 psi is it still jerky?

I also checked the charge pressure again today. It was 150 psi when I first started it up then it slowly decreased unitl is was just under 130 psi after 5 minutes or so of idling at near full throttle. I was alone so I couldn't see what the pressure did when I tried to move the machine. I think I will replace this valve since that's below what the manual says. The manual says it's imperative that the pressure be between 150 and 190 psi. Thanks

 

[palmtree]

I also checked the charge pressure again today. It was 150 psi when I first started it up then it slowly decreased unitl is was just under 130 psi after 5 minutes or so of idling at near full throttle. I was alone so I couldn't see what the pressure did when I tried to move the machine. I think I will replace this valve since that's below what the manual says. The manual says it's imperative that the pressure be between 150 and 190 psi. Thanks

I thought I would also add that when the machine was running up on jack stands the wheels turn really nicely and smooth on both sides. No strange noises when each lever is stroked individually or simultaneously. Also thought I might take a video and post it for you guys to see/hear if that would help. Thank again.

 

[antfarmer2]

I thought I would also add that when the machine was running up on jack stands the wheels turn really nicely and smooth on both sides. No strange noises when each lever is stroked individually or simultaneously. Also thought I might take a video and post it for you guys to see/hear if that would help. Thank again.

I would put it up on stand and set up your video so you can see what your pressure is while you stroke your levers and work your bucket up and down do not max them out then let it set and repete many times and see if it gets better as the air works it's way out posting the video will get more eyes on it

 

[antfarmer2]

I would put it up on stand and set up your video so you can see what your pressure is while you stroke your levers and work your bucket up and down do not max them out then let it set and repete many times and see if it gets better as the air works it's way out posting the video will get more eyes on it

I would make sure the oil is good and filters are good watery foamy oil is not to specs

 

[palmtree]

I would make sure the oil is good and filters are good watery foamy oil is not to specs

I talked to the guy that rebuilt the pumps and motors a described my situation. He thinks I have air being introduced through the suction hose or the fitting on the suction side of the gear pump. I'll check into that soon maybe tonight if I have time. He said the motors should be good. Said they have all new rotating assemblies. He asked if the oil is foamy. It really is. I used a clear hose when I ran the pump case drain test and the oil was really frothy looking. The oil I put in was a brand I didn't recognize but it said it met JD J20A specs which is what my service manual calls for. Should I buy the same oil again? Its the only one I could find locally that was labeled as meeting the j20a and the 304b NH standard. I sure hope this is it! Thank.