Lull 644B owners- Whats normal - whats not

[Andy1845c]

Hey all,

I recently purchased a 644B that has been sitting for.... at least 3 years - possibly much longer. I just had the injection pump rebuilt to get it running again and now am working through some other issues and am wondering if anyone has input.

1. When I start it, it takes maybe 30 seconds before the hydraulic functions will actuate. You can hear the engine load a little, like the pump took that long to build pressure. Not sure what to make of this as there are no electronic controls that do anything like this.

2. The steering is "bucky" - seems the worst in crab steer mode. The wheel bounces and fights being turned. Its worse the faster you try and turn it.

3. Fully boomed out at 0 degrees (angle not temp) - I can't raise the boom unless I give it some throttle. Boomed in I can raise it at idle, though slow. Similarly I seem to be fighting the counterbalance valve on the fork curl function - at idle it will move in one direction, but needs some throttle to move the other direction. I did put almost all new hoses on it, and it sat for so long I am sure the system has/had air in it - but I have run it quite a bit now and haven't seen a ton of improvement.

4. I haven't got the transmission to shift. It feels weak. Has trouble getting over minor bumps. I will preface this one by saying I changed the oil and pulled the filter and the filter was awful. The oil was dirty but no water or metal in it. I didn't have a new filter and needed to move it so I cleaned the old one best as I could and put it back in. I have a new one arriving this week. I assume that could cause the issues I am seeing.

5. I am having a bunch of issues with the frame leveling. someone previously disconnected the front cylinder. Fearing it was full of water or something I took it apart. The inside is fine but one counter balance valve was rusty. I have a new one ordered. Twice now i have suddenly had the frame lean all the way to one side while I was playing with the steering - not even touching the frame control. I don't see how these systems are interconnected.


I have never owned a telehandler before and have limited operator experience so hoping some of you can maybe offer some input.

 

[benmech]

Hi sir.
It seemes that your hydraulic system is starving , there should be a screen in your hydraulic tank , check if its not blocked.
NormalLy if machines are sittting for a long time they get some sludge build up in the hyd system and that is funerable for screens and filters.
Even if your oil looks clean , just go trough your filter system

 

[Roadoil]

I went all through this with my 844-42-C sounds like your relief valve pressures are off too low. Same with steering pressure.

Idk on your but the 844 has test ports under the seat area where you hook up a pressure gauge 5000 psi and set pressures for the 2 main relief valves on valve block.

Yours may be different but it's a similar procedure gotta adjust the relief valves to spec to work together.

 

[Roadoil]

On the frame leveling on its own you might check the control valve maybe seals bad and it bypasses fluid possibly why they disconnected front cylinder.

 

[Andy1845c]

Thanks for the replies.

I did clean the hydraulic tank out before I ran it. I pulled the cover off the top, fearing there could be water or sludge in it. It was very clean. The pick up screen had fallen off, so I got a replacement and installed that. So I know there is nothing restricting the pick up.

I have a pressure gauge but need to get the correct quick connect for the pressure ports.

My *guess* as to why the front leveling cylinder was disconnected is one of the counterbalance valves sits in a recess that points upward. It fills with water in the rain and the whole valve was rusted. I am lucky I was able to get it removed ok. I am thinking it jammed up and wouldn't move and caused the frame to not be able to tilt in one direction. JUST A GUESS. I wish this thing could talk. I have zero history on it past it looks like it sold at auction in 2008 in Florida. Somehow it made it to Minnesota now. Bought it with the story the fuel tank had gotten algae in it and fouled the injectors. Someone had put injectors in it and it would run but wouldn't start without ether. Ended up having the pump rebuilt and new injectors. The fuel tank was very sludged. I got that all clean now.
The transmission wouldn't engage when I got it but that turned out to be an electrical issue. It had been really cobbled on the wiring.

But bottom line - I don't know why someone parked this machine.

 

[Roadoil]

Thanks for the replies.

I did clean the hydraulic tank out before I ran it. I pulled the cover off the top, fearing there could be water or sludge in it. It was very clean. The pick up screen had fallen off, so I got a replacement and installed that. So I know there is nothing restricting the pick up.

I have a pressure gauge but need to get the correct quick connect for the pressure ports.

My *guess* as to why the front leveling cylinder was disconnected is one of the counterbalance valves sits in a recess that points upward. It fills with water in the rain and the whole valve was rusted. I am lucky I was able to get it removed ok. I am thinking it jammed up and wouldn't move and caused the frame to not be able to tilt in one direction. JUST A GUESS. I wish this thing could talk. I have zero history on it past it looks like it sold at auction in 2008 in Florida. Somehow it made it to Minnesota now. Bought it with the story the fuel tank had gotten algae in it and fouled the injectors. Someone had put injectors in it and it would run but wouldn't start without ether. Ended up having the pump rebuilt and new injectors. The fuel tank was very sludged. I got that all clean now.
The transmission wouldn't engage when I got it but that turned out to be an electrical issue. It had been really cobbled on the wiring.

But bottom line - I don't know why someone parked this machine.

On these Lulls if you don't have full hydraulic pressure light goes out on transmission they won't go into gear.

Mine also has hydraulic E brake needs to be off to go into gear.

 

[Roadoil]

Thanks for the replies.

I did clean the hydraulic tank out before I ran it. I pulled the cover off the top, fearing there could be water or sludge in it. It was very clean. The pick up screen had fallen off, so I got a replacement and installed that. So I know there is nothing restricting the pick up.

I have a pressure gauge but need to get the correct quick connect for the pressure ports.

My *guess* as to why the front leveling cylinder was disconnected is one of the counterbalance valves sits in a recess that points upward. It fills with water in the rain and the whole valve was rusted. I am lucky I was able to get it removed ok. I am thinking it jammed up and wouldn't move and caused the frame to not be able to tilt in one direction. JUST A GUESS. I wish this thing could talk. I have zero history on it past it looks like it sold at auction in 2008 in Florida. Somehow it made it to Minnesota now. Bought it with the story the fuel tank had gotten algae in it and fouled the injectors. Someone had put injectors in it and it would run but wouldn't start without ether. Ended up having the pump rebuilt and new injectors. The fuel tank was very sludged. I got that all clean now.
The transmission wouldn't engage when I got it but that turned out to be an electrical issue. It had been really cobbled on the wiring.

But bottom line - I don't know why someone parked this machine.

There is a procedure to adjust the relief valves such as checking pressure while extending boom, checking steering port pressure etc. it's usually around 3000 psi max. You don't want too much will over pressure system or not enough won't lift anything heavy etc.

The Lulls use a dual pump when I got my 844 42C only had steering nothing else no boom wouldn't go into gear
The PO ran the pump too low destroyed the seals in 2nd stage pump.

I just ended up getting a new after market pump they had to custom make it took 2.5 months but was reasonable $1300 but even after installing everything was weak would drive though I found a relief valve stuck open with plastic seal from the pump causing problems.

 

[Andy1845c]

I saw your post about the relief valve stuck. Thanks for posting that. I wish more people followed up like that.

I did pull mine out today to inspect. It looks different than yours. I didn't see anything lodged in it.

I also pulled the high pressure filter out. Could use a new one but wasn't awful. Some sludge but no metal or debris or anything.

At this point I need to get the fittings to attach my pressure gauge I think and see what I am actually getting for pressure.

Will report back...

 

[Roadoil]

There are 2 types of hydraulic systems with these Lulls one is mid inlet which is probably on yours so different than mine.

But you probably have 2 relief valves. Each set of valve blocks usually have one.

You can check that the relief valve functions properly by depressing it with a tool should have firm resistance but smooth.

 

[Andy1845c]

Screwing around a little more with this today -

I threw a pressure gauge on one of the aux quick couplers and I get around 2500 psi at idle.

I am not a hydraulics wizard - but looking at the drawings in the manual it looks like there is a main pressure relief set at 3175 psi. I am wondering if this is what I should be seeing on the aux line?

The counterbalance valve from the front frame leveling cylinder is stamped 3500 psi - this is higher than the system pressure. Does this seem correct? I have no reason to believe its not the original valve.

*****EDIT****
Answered my own question but will leave it here in case it helps someone else.
Schematic shows it to be a 3500 PSI valve.
I think I am thinking about this wrong. 3000 PSI acting on one side of the cylinder will generate well in excess of 3500 psi on the opposite side - thus opening the valve. Someone smarter will hopefully correct me if thats not how these work.

 

[Roadoil]

Screwing around a little more with this today -

I threw a pressure gauge on one of the aux quick couplers and I get around 2500 psi at idle.

I am not a hydraulics wizard - but looking at the drawings in the manual it looks like there is a main pressure relief set at 3175 psi. I am wondering if this is what I should be seeing on the aux line?

The counterbalance valve from the front frame leveling cylinder is stamped 3500 psi - this is higher than the system pressure. Does this seem correct? I have no reason to believe its not the original valve.View attachment 304805View attachment 304806

That's the max pressure rating of the valve doesn't have anything to do with system pressure settings.

 

[Roadoil]

Screwing around a little more with this today -

I threw a pressure gauge on one of the aux quick couplers and I get around 2500 psi at idle.

I am not a hydraulics wizard - but looking at the drawings in the manual it looks like there is a main pressure relief set at 3175 psi. I am wondering if this is what I should be seeing on the aux line?

The counterbalance valve from the front frame leveling cylinder is stamped 3500 psi - this is higher than the system pressure. Does this seem correct? I have no reason to believe it's not the original valve.View attachment 304805View attachment 304806

There should be a block of test ports to check pump 1, pump 2, steering pressure etc.

That's where you need to test pressures at.

 

[Roadoil]

Test ports

 

[Roadoil]

The system will have an idle pressure and max pressure when at high rpm's.

 

[Andy1845c]

I ordered what I hope is the correct (PD242) coupler for these last night. Supposed to be here next Monday... Hoping it shows sooner and I can see what I get. I just happened to have a spare quick coupler around that I had fittings to attach to my gauge so I thought I would make sure I didn't have super low pressure on that or something pointing to a pump being bad or something.

 

[Roadoil]

Ok but you have a dual stage pump one could be fine other low pressure.

On my tilt cylinders there is a 12v solenoid on the back cylinder that locks it when boom is out certain length via hall sensor signal. You can check if it's getting power 12v with a power probe.

By default it's locked and it unlocks to allow crane tilt if boom hall sensor detects boom not out past certain length.

 

[Roadoil]

Yeah that's it.

 

[Roadoil]

my experience with hydraulics was working on sweepers that use 12v direction solenoids these Lulls are total mechanical systems and complex took me a good month or so to figure mine out.

Just takes time and unfortunately very few know how to work on these tractor mech Craig helped me out a lot.

 

[Andy1845c]

I got impatient and made up an adapter to thread on in place of the quick connects. On pump 2 I get 2500 psi at idle- but only when I am actuating a function. When I try to roll the forks down or level the frame I get to a point and then my pressure drops, and I can't get it back until I re-center the control. Same thing happens when I stroke the fork roll cylinder all the way out and deadhead it. Its like over a certain pressure a relief opens or something. I have steady pilot pressure the whole time. I'm not quite following yet on the schematic how it sends pressure to that circuit only when needed.

The steering is even more confusing. I don't know if that is related or not. It steers fine in 2 wheel steer mode but roundor crab it will only steer a little bit before the wheel doesn't want to turn. Turing it super slow doesn't help. Steering pressure does drop to about 1000 when the wheel binds up - but doesn't go away.

 

[Roadoil]

Your steering should be 2200 min.

You shouldn't have pressure drops when activating functions.

Here are some test procedures on mine 844-42C it's very similar to the 644 but yours may be different