41b Hydraulic issues

[futuresweets10]

Ok, ive got some pictures now.....

In the first pic you can see the small hydraulic line, this line runs from where you see it to the valve assembly for the front end loader, under the machine. The line on the right is the line that runs straight to the bottom of the tank.

--------------------------------------------------------------------------------------------------


This next picture is a view of the front of the pump (should be pretty self explanatory) The top line is the pressure line out and the bottom line is the main line in from the tank. The valve assembly with the hard line comming out is what I assume to be my pressure and flow adjustments. This hard line runs to the back of the valve assembly thats on top of the pump (the one that is seen in the first pic)

------------------------------------------------------------------------------------------------


In this pic you can see the valve assembly on top of the pump from the back side, you can see where the other end of the hard line goes in this pic.

---------------------------------------------------------------------------------------------
And one last pic.... This shows the slight damage to the fitting on the hard line where the hard line connects to the front of the pump. This damage happened in shipping and it does not leak. From what it looks like I feel it is safe to assume the line is not restricted due to the fitting being bent, but I cant be sure.

 

[wdchyd]

You have some good advice here, Akkamaan mentions Load Sensing/variable pressure compensated pump which is spot on....JJ mentions guages....

All this means is you're gonna need technical manuals and/or a trained eye/wrench turner that knows this setup....

This pump is not like tractor gear pumps (dumb pumps)....they just move oil fixed displacement according to rpms and HP.....Pretty straightforward....

Your piston pump is what I call a smart pump.....does a lot more internally than just moving oil....It varies pressure and flow automatically....thus "Smart Pump"

Did you say this a new pump?....Why the rust on the mounting pilot and drive spline....Could it be the pump is not as new as they said when you bought it.....You may have to pull it and have CAT or Hydr Shop check out internals and have pressure tested on test stand to at least rule out pump efficiency

I think at this point if you brought this to my shop I'd pull it, open it up and at least make sure it was not trashed/worn......some people can say they rebuilt these but they only change seals....a trained eye might spot trouble inside...

Why would someone sell this pump cheaper than the 2000. Cat Pump??

I suppose if it was new from Cat the adjustments would be tweeked on their test stand before shipment....being a aftermarket unit it just might need proper adjustments....No??

 

[futuresweets10]

You have some good advice here, Akkamaan mentions Load Sensing/variable pressure compensated pump which is spot on....JJ mentions guages....

All this means is you're gonna need technical manuals and/or a trained eye/wrench turner that knows this setup....

This pump is not like tractor gear pumps (dumb pumps)....they just move oil fixed displacement according to rpms and HP.....Pretty straightforward....

Your piston pump is what I call a smart pump.....does a lot more internally than just moving oil....It varies pressure and flow automatically....thus "Smart Pump"

Did you say this a new pump?....Why the rust on the mounting pilot and drive spline....Could it be the pump is not as new as they said when you bought it.....You may have to pull it and have CAT or Hydr Shop check out internals and have pressure tested on test stand to at least rule out pump efficiency

I think at this point if you brought this to my shop I'd pull it, open it up and at least make sure it was not trashed/worn......some people can say they rebuilt these but they only change seals....a trained eye might spot trouble inside...

Why would someone sell this pump cheaper than the 2000. Cat Pump??

I suppose if it was new from Cat the adjustments would be tweeked on their test stand before shipment....being a aftermarket unit it just might need proper adjustments....No??

The people I bought the pump from could not tell me weather it was new or used. When i finally received it (fedex lost it for two weeks) it still had the factory caps over both of the ports on the back. Every indication and everthing I could find pointed to a brand new pump that had never been mounted. The paint was flawless and I could tell it hadnt been re-painted. The reason it was so cheap was because the seller was an e-bay seller who sells medical equipment and supplies that they purchase from shipping companies after its lost or not claimed. They really didnt know how they acquired the pump or really what it was. When I bought it on e-bay it had been on there several months and didnt have any application information, just a part number.

Believe it or not, the rust you see was not there when I received the pump from fed-ex, that is all 100% surface rust that occurred once the pump was installed.



Here is a pic of the pump how i got it....

 

[mmurphy]

Since you are a auto tech I would think these guys can help you out.
The best advice I can give to you is get the service manual for this machine. I would imagine the manual will run 150 bucks or more, but you will need it for other info. in the future. The manual will give a good description of what you have there, and maybe stuff you do not care.(probably help you fall asleep)Manual will also help in steps to take to determine from charge pump on up the hydraulic system.

 

[futuresweets10]

Since you are a auto tech I would think these guys can help you out.
The best advice I can give to you is get the service manual for this machine. I would imagine the manual will run 150 bucks or more, but you will need it for other info. in the future. The manual will give a good description of what you have there, and maybe stuff you do not care.(probably help you fall asleep)Manual will also help in steps to take to determine from charge pump on up the hydraulic system.

I don't know if I'm looking at the wrong thing or what, but I cant find the manual for under about 700 bucks.

 

[wdchyd]

I'm kinda surprised you didn't get any feedback from the Heavy Equip Forums that you previously posted on....it's more up their alley for sure....

 

[wdchyd]

I don't know if I'm looking at the wrong thing or what, but I cant find the manual for under about 700 bucks.

That's ironic cuz not long ago I was talking with a coworker and the conversation came up about shop manuals.....the consensus was the older the machine/the shop manual becomes more valuable than the machine itself:confused2:

 

[futuresweets10]

Well, a guy (worked for cat for years) came by the shop this morning and looked at how it was acting. He said it looks like the unloader valve (think thats what he called it) system had trash in it and it was keeping the pump from knowing it needed more pressure.

Long story short I just spent the past 5 hrs pulling one of the two valve assemblies out from under the machine and Im ready to give up. Figured it would be easy to figure out once I got it out, but I guess I was wrong. I am about ready to scrap this thing.... the pins that hold the levers to the top of the valves DO NOT COME OUT!!! If I try beating them out I am likely to bend the valve..... I FUC*ING hate cat at this point....

I obviously have bad O-rings in the bucket valve, but there is no way to replace them if I cant get the linkage off of the valve.

 

[mmurphy]

My apologies. That is absolutely rediculous. I looked on line also.

 

[futuresweets10]

I am completely lost when it comes to these valves. The valves do not appear to be able to come out of the valve body (or block) from either end. Both ends have parts attached that do not come off and look like it should pull out from the other end. There are springs, O-rings, and a TON of ball bearings that fall out with every piece you remove and no way to hold the parts back in to re-assemble. I am beginning to think that cat made the entire valve assembly to be non serviceable (even O-rings). I know a new valve assembly from cat would be a few thousand and I dont have that nor do I want to sink a few thousand into one valve assembly not knowing if the other one is bad or has problems too. It looks like cat made this machine so that if any part (pump, cylinder, valves, etc.) ever had a catastrophic failure it would cost ALOT more to fix than the machine is ever worth. The local cat shop wants about 100 an hour to look at it and they cant say what is repairable (ie, cant say if they are capable of rebuilding valves or not). This leads me to belive if I took it to them they would put brand new valves on and charge me for the labor to change them (I can change valves myself!!!!). Im at a point where I am ready to take a torch to it and scrap it...... The sad part is that they guy who came by earlier (who worked for cat) said he had never seen a machine in such great shape for its age.