JLG 400S manlift

[tractormech]

Hello all-Any JLG manlift gurus out there? I got a call on a 2004 JLG 400S serial is 0300076034. Customer says that in the summer the oil seems to get really hot and the swing and travel gets real slow to the point that he shuts it down til the next day. In winter it's not as bad but he moves the lift and shuts it off, does his work and then starts up, moves, repeat. I downloaded the manuals from JLG but before I start looking I thought I'd ask if someone has dealt with this issue. Wrong viscosity oil? Maybe a bypassing relief valve heating the oil up? Any ideas, advice of experience would be appreciated. Thanks guys!

 

[Jeff14889]

That serial should means the lift should have ADE system, you could check the function speeds with a jlg handset if you have one, if it’s pre-ADE, then the joysticks themselves have cards that can be adjusted for the speeds. How does he know the oil is heating up too much? Travel and swing hydraulics have nothing to do with each other, each runs off a separate pump.

 

[tractormech]

Thanks got the reply! First,I'm going off of " he says" so there's no telling. I noticed the swing pump was seperate so I figured the swing was a "stand alone" type deal. You said cards in the joysticks....i just wonder if the wires may be corroded and/or half broken from the boom.being ran in and out a million times over the years? Had that issue with an old Snorkelift one time. I need to see if the swing works right from the ground controls - that may show me something? I've not seen the machine yet but was fishing for info. Thanks again!

 

[willie59]

No way anyone can answer this as it would require verifying what the customer stated, that is, oil getting hot. If it is in fact getting hot, say, 180 deg F or higher, yes, pumps and motors are going to do weird stuff which will affect operation. Many things can cause overheated oil, faulty relief valve, worn pumps or motors. Again, you'd have to verify that's what's happening. What is unusual if an aerial lift operating proper, proper rotation speed and proper drive speeds, then as the machine is used they both slow down, that's not usual an indicates something is wrong, but again, it would require you verify that's what's happening. And yes, an area like Florida, you should probably be using an AW-46 or even AW-68 hyd oil. But again, that's not necessarily the issue if something is causing the oil to get hot, gotta verify.

 

[Midnightmoon]

It's always hard with customers version of the problem. Some say I have no idea its broke fix it, some know exactly what's wrong, others try to describe it so well it gets cloudy what's not wrong or if everything really broke at the same time. Gotta go with the first version and get your hands on the machine to get the whole story.

Let's say both issues happened at the same time. Well we know it's a stretch that two separate systems failed at the same time but we have all seen it. If true I'd check the engine first. Is it loosing power when it warms up. Overheating.
Maybe this happens at a certain height and pumps are starved for hyd fluid.

If this was easy everyone would be doin it. I like to prepare before I start on a diagnostic adventure. This one will be just that.

If this machine does this all the time when it warms up no matter what position it's in. I'd look at the engine first. We had a similar issue that when warmed the harness shorted out and one cylinder would misfire and the machine was sluggish. A perfect storm just enough heat expanded the wire harnes to expose a nicked wire to short out on a bracket. It took a minute okay alot of minutes to find that pin hole size short. The deutz wire loom doesnt last long rubbing on sharp edges. I didn't look up this machine but I'm saying sometimes it's not hydraulic at all one cylinder misfiring can cause hydraulic issues

 

[tractormech]

It does have the Deutz engine. I'll need to get to the machine. This will be a witch hunt I'm afraid. I need to get in the parts books and see if there's suction filters in the tank. He says swing and drive get slow but the chances of two bad pumps are kind of slim. I need to check the hydraulic schematic and check all the relief valves too. This will get interesting,and probably time consuming as well. Thank you to everyone who is offering advise. I appreciate it.

 

[Midnightmoon]

That's an oil cooled deutz. The one I was referring to was a new tier 4 machine. I've put many head gaskets it those engines from people eithering them. Could be simply a bad head gasket that's causing low compression when it heats up. If it's not you likely have multiple issues going on. Customer may have added that it drives slow too or noticed oh yeah it doesnt seem to move as fast. That was probably a problem before something fell on the basket harness. Good luck

 

[tractormech]

That's an oil cooled deutz. The one I was referring to was a new tier 4 machine. I've put many head gaskets it those engines from people eithering them. Could be simply a bad head gasket that's causing low compression when it heats up. If it's not you likely have multiple issues going on. Customer may have added that it drives slow too or noticed oh yeah it doesnt seem to move as fast. That was probably a problem before something fell on the basket harness. Good luck

Just to clarify- he says the hydraulic tank seems to be getting very hot. I haven't seen the machine yet but thinking a stick relief valve may be causing the heating and the oil gets thin and the pumps get slow. Possibly suction filters that haven't been cleaned/ changed it whatever starving the pumps. Wrong oil in the machine that gets too thin. Any or all these things could contribute to the issue. Thanks for your input. There's stuff we mechanics have seen that isn't in a manual. Experience is a great teacher. Thanks again!

 

[Midnightmoon]

It's just speculation at this point. It's not one stuck relief it would have to be two Its 2 different systems slowing down. Clogged hyd filter low hydraulic oil. Could be a bad tilt sensor who knows. I wouldnt spend too much time trying to find a cause for the 2 system failure. This is a service call fix not an over the phone fix unless the customer is a competent mechanic and your willing to spend hours walking home though it

 

[tractormech]

It's just speculation at this point. It's not one stuck relief it would have to be two Its 2 different systems slowing down. Clogged hyd filter low hydraulic oil. Could be a bad tilt sensor who knows. I wouldnt spend too much time trying to find a cause for the 2 system failure. This is a service call fix not an over the phone fix unless the customer is a competent mechanic and your willing to spend hours walking home though it

You're right. He wants me to come work on it. He's not a mechanic,he's a builder. He has no idea what's wrong,he just can't use his machine like he needs to and wants it right. He gave me the symptoms he's having to give me a starting point. I was asking about it here because there's people with tons of manlift experience. I'll need to study the manuals and maybe take a heat gun and hunt for hotter oil at a hydraulic valve and do some pressure tests or whatever. I have to get a game plan together
Once again,I really appreciate all the advice.

 

[Midnightmoon]

Personally I wouldnt work on a lift if the customer wont fix it to the point it will pass a ansi inspection. If you work on a lift and tell the customer its fixed but wont pass a ansi I hope you have good insurance. I like to prepare and hope someone has come across the same problem so it's an easy fix. With more info this might be one of those but it doesnt happen that often. Are you set up for ansi inspections?

 

[tractormech]

I've not worked on manliest enough to talk about. Is the ansi certification a requirement for repair work? If so I'll let it go. Sounds like a struggle to get someone with one machine to do the certification anyway.

 

[Skidloadertech]

Here in Canada the Ministry of Labour requires a safety inspection for aerial equipment and material handling equipment by a “competent person.” It doesn’t necessarily matter who worked on if it doesn’t have a current safety certificate it can be grounded and taken out of service by an MOL officer.
If you are not giving it a safety certificate you could even put a disclaimer on the bill. Not to say you couldn’t be liable if something bad happened (lawyers will try anything) but generally I wouldn’t worry about it if you aren’t modifying safety systems or something stupid like that.
However that is from Canada not sure of your requirements.

 

[Vetech63]

Manlifts carry people which is why the standards are so strict. One faulty repair could cause a injury or death. If you don't have insurance to cover that liability you would be best to pass on that particular job. The owner should understand based on your inexperience with that type of machine.

 

[tractormech]

Manlifts carry people which is why the standards are so strict. One faulty repair could cause a injury or death. If you don't have insurance to cover that liability you would be best to pass on that particular job. The owner should understand based on your inexperience with that type of machine.

True enough. Everybody wants to sue everybody for anything. It's hard to make a living like that.

 

[Txhayseed]

Driving the boom heats up the hydraulic system faster than anything. Some jlgs have a built in thermometer built into the hydraulic site glass. If its getting hot while in transport i would suspect a wheel motor. As hard as it is to believe depending on how old it is there where some jlgs a few years back with this problem. The issue, hydraulic tanks where being installed on the assembly line with the thread protection caps getting pushed into the tank. They would get sucked up and fluid restricted resulting in wheel motors burning up. Sounds crazy but it was a real issue for a while. Some booms got two or three wheel motors before the issue was discovered. But as others have said and and have been involved with one particular case involving a death and once causing an injury both on boom lifts.. Lets just say it is something you dont want to deal with, right, wrong doesn't matter your getting brought into it.. Aerial is the one thing that will get you sued quicker than other piece of equipment..