Newbie Alert! New LMTV in DFW

[hike]

@Suprman likely has the right CTIS controller for your unit and more important: will tell you if he doesn't and confirm a unit he has is not 5 solid.

Using a 900 series is not a big deal, you just have to pull pins on the controller to isolate the J1939 circuit from it. There are several recent threads here covering the CTIS schematics and different programing using various power and ground combination.

We love our CTIS though it isn't the first thing I'd start with. There is a thread highlighting must do's; @GeneralDisorder has a very good list—

 

[IronhorseTX]

@hike - thx! I reached out to him and should be good to good.

now to start on the hydraulics issue. Glad there is a long weekend coming up!

 

[MatthewWBailey]

FYI on my 1078A1, I only have the cab lift now. Spare tire and kneeling cylinders deleted. I'm adding an 24v electric over hydraulic backup pump power unit to the manifold.

 

[IronhorseTX]

FYI on my 1078A1, I only have the cab lift now. Spare tire and kneeling cylinders deleted. I'm adding an 24v electric over hydraulic backup pump power unit to the manifold.

very interested! This is what I need to do asap since the hydraulics aren't working and I can’t get the cab to tilt.

 

[Ronmar]

so what happens when you select cab and raise on the manifold and use the hand pump?

 

[IronhorseTX]

so what happens when you select cab and raise on the manifold and use the hand pump?

nothing unfortunately. It seems there’s no pressure in the line.

 

[GeneralDisorder]

nothing unfortunately. It seems there’s no pressure in the line.

The MOST COMMON reason for nothing happening is that the system is low on fluid. Check the fluid level. Make sure you only use MIL-PRF-5606 in the system. They *can* operate on regular ATF if completely flushed but you need a system that's trying to work to do that.

 

[IronhorseTX]

Good copy - Once I can get back to the truck later today I’ll start poking around and see what’s what.

 

[MatthewWBailey]

very interested! This is what I need to do asap since the hydraulics aren't working and I can’t get the cab to tilt.

I was mistaken on the voltage. I bought the 12v version since the 24v is so much more expensive. I could probably find a 24v motor to swap into the unit but even the 12v will work fine. I have a 3rd 12v only battery anyway.

6 Quart 12V KTI Double Acting Hydraulic Pump | DC-4499

*Free Shipping in the Lower 48 States*

johnsontrailerparts.com

I'll be plumbing this into the hand pump ports with T's. I guess it could go into the AOH pump ports too. But I'm leaving my AOH installed. No harm in Having 3 Hydraulic power sources. When you're out of air, the hand pump is a pain unless you swap in a bigger one like Ron did.

The single acting pumps would work too since the existing valve block has the appropriate valving. Pumps come with a check off the pressure line so it's pretty cut and dry.

 

[Ronmar]

Thats one reason i went manual, dead easy. Two hoses, pump, adjustable flow control(for lowering speed control), couple of fittings and done. No wiring…. Uses plain common AW-32 hydraulic oil available everywhere…

Totaled it up for someone last night, just over $250 in parts from surpluscenter…

if you are not getting anything from the hand pump, either it is empty or the seals in the control valve are shot. The hand pump has a allen head fill plug to the left of the handle when facing the pump…

 

[Third From Texas]

Yep, extremely common for the reservoirs to go dry if there is a leak (and with 20+ year old rubber o-rings, there's always a leak eventually).

Top off both reservoirs 1) the one at the manual pump and 2) the one behind the cab (next to the hydraulic pump). Pump, fill, pump, fill until you get pressure then cap them (rinse repeat as needed).

If there is a leak, that's when you'll find it. Typically the leak will be at the main pump (misting towards the back of the cab) or at the cab latch (spraying at your face).

It may even get your cab up (which I would prioritize).

The repair kits for the latch and main pump are cheap and there are plenty of videos walking thru the rebuild. It's mostly just replacing the deteriorated o-rings. The hydraulics is typically one of the easier systems to get working, IMO. And IMO, you want to at least take a stab at it (before you start looking at alternative replacements for the system). As I said, it's almost always the pump o-rings or the cab latch o-rings. But if it's something else, adding new things into the mix is only going to add more work and still never get that cab up. Find why there is no fluid first. Changing to another source to move the oil can come later.

ymmv

@fuzzytoaster is up your way. He fixes up trucks and sells them. He's a good contact to have.

 

[IronhorseTX]

@Third From Texas - good to know!

When I tried the cab tilt yesterday it’s actually making the chug chug sound but nothing is happening. Is there a way to check the hydraulic fluid?

@fuzzytoaster - pleasure to meet you! - Great to hear there’s a local near by!

 

[GeneralDisorder]

There's a dipstick that unscrews from the air operated pump right on top.

The suspension cylinders often leak also. I've seen that quite often.

 

[MatthewWBailey]

nothing unfortunately. It seems there’s no pressure in the line.

I went thru this madness with my spare tire lift when it crapped out. Verified fluid, pulled a line to verify flow, but turned out to be those spring loaded checks in the cylinder were seized w/air (one side). I never did get it freed up until it was on the beach and hit the check with a small center punch. It freed up and I got a bath, good thing for safety glasses. If you're fluid is good and you're pumping against pressure (hand pump is hard), I'll wager one of those checks is seized.

 

[Ronmar]

A seized safety check would still allow the pump to build pressure, (hydraulically locked, handle doesn’t move). If you can pump with little resistance, either you are trying to pump air(reservoirs empty) or something is allowing fluid to go from supply to return.

which brings us to the second most likley issue. Bad oring seals in the control valve assembly allowing fluid to pass from the pump pressure output to the return with little resistance…

 

[Third From Texas]

And above all else, if/when you get the cab up...block it up with a 4x4.

@chucky has a good story to tell about the fluid dumping out in an instant when he had the cab up to work on the system. He got to use his head to hold the 4000# cab up until he neighbors and rescue arrived to take some of the load off his crushed skull.

Fortunately, he was already a little different before so he recovered with no noticeable change...

 

[Third From Texas]

When I tried the cab tilt yesterday it’s actually making the chug chug sound but nothing is happening.

That's a good sign that the pump is working.

Get some fluid in there (both reservoirs) and find if a leak exists.
That's the most common fault.

 

[IronhorseTX]

Small victories- found the reservoir and dipstick. It’s bone dry. I plan to head up to the auto parts store later tonight and pick some up. I read in another post that it takes 27 gallons, does that sound right?

Another basic question, where do I refill it? Can anyone point me towards a schematic or FAQ?

 

[IronhorseTX]

@Third From Texas - tell me you’re kidding about the skull crushing action with @chucky ! OUCH!!

Thanks for planting that thought in the back of my head - pun intended

 

[Ronmar]

No he is not kidding. You need to block the cab if you are ever opening the hydraulic system with the cab raised. There are safety check in the cab and tire cylinders, that should block the flow if it starts to move too fast. I have tripped mine lowering the cab too fast on my adjustble system. There are restricted orifices in the control valve that restrict flow and keep it low enough that the safeties do not trip.

His cab safety apparently didn’t work and dropped the cab onto and trapped him when he opened the cab latch for service. His cab also wasn’t raised all the way. It normally goes past the balance point when fully raised so this shouldn’t be an issue, but best practice is to install a crutch whenever opening the hydraulics when the cab is up. It however doesn’t go far past the balance point, and if you set the control to lower you can push it back over by hand... He was lucky!

you fill the aop reservoir thru the dipstick/plug hole. Hand pump has an allen head filler plug outboard rear corner. Fill and make sure the plug is back in place on the hand pump. The check valves in the system direct return fluid to the hand pump first to insure it is full, then back to the AOP reservoir. You leave the plug off it will gush…