Hey guys, I came across this website searching for answers on our skid steer. My deceased brother had his skid in the bobcat shop for a new 2sp when hewas killed on a jobsite...when that was completed Bobcat said it needs a charge pump. Symptoms are hyd oil pressure light, then alarm and the wheel controls fighting you then either shutdown or machine stops all movement of the wheels. Is there a way to test this pump? Bobcat said it was internal to hydro pump but I had another independent mechanic tell me over the phone that it simply bolts on to the left side of hydro assembly? I want to try and fix this for his estate at home(to save $, his funeral took everything up to now) and am in need of help. Thanks again. Again, if I could get some direction on how to diagnose/test and r/r I would be in your debt!
Help Support SkidSteer Forum:
Firstly, sorry to hear about your brother, that's horrible.....
As for the machine, there is no charge pump as such, it uses the oil returning from the main hydraulic pump, the one you have been told that bolts to the end of the drive pump.
Does the machine still lift and til the bucket well? if so, i'd suspect the pressure sender is bad, telling the computer to shut down tha machine.
As for the machine, there is no charge pump as such, it uses the oil returning from the main hydraulic pump, the one you have been told that bolts to the end of the drive pump.
Does the machine still lift and til the bucket well? if so, i'd suspect the pressure sender is bad, telling the computer to shut down tha machine.
We replaced the pressure sensor already on a whim...but machine will come to a complete halt and sticks will start fighting the operator and making lots of noise. The bucket and lift seem to work ok but when the alarm starts it will slow them down and they get jumpy. Thanks for the condolences he was a good person and wonderful father and older brother of 14mo...
Forgot to add that this condition is much more prevalent in hot weather. If its cold outside 40 or below, it can run for few hours and when its hot a few minuts sets it into motion.
You could check that the drive belt is tight too, if it is slipping, it will reduce the hydraulic flow/pressure and can make the light come on.
Can you remove the pressure sender and install a manual gauge to see what the pressure really is? it should be around 120 PSI from memory.
Working well when cold could mean the pump is going bad, as the oil thins it is harder to keep the pressure and flow up. The only way to know for sure is to get the pump tested, they get the oil up to temperature then do a flow/pressure test then you know for sure if the pump is worn or not.
Pressures at sending unit r at top of spec per mechanic. Belt was very tight and actually broke the adjuster at top of spring today trying to loosen it. We decided this morning to pull hydro unit and get tested...about 2.5 hr and it was ready to come out except for pulley. Wow is that thing on there. Main nut was cross threaded on and one of the bolts that the puller attaches with is stripped out. Any ideas on getting it off? Right now it's sitting with a puller tightened to the max and cooling down after heating with torch. And I thought we were heading to hydraulic shop about noon...not!
Normally you take the pump and engine out as one to make removal easier.
The shaft will be a taper, that's why it's so tight, you need to get pressure on it and shock it loose. I would have thought the heat would have gotten it free.
So u can pull the engine and hydro quicker than pulling hydro unit out the front? We left the puller on the pulley over night and next morning I tightened it as much as I could and smacked again with hammer and she popped off. Wont get a quote for repair for another week. Prob should of got a reman and been running.
What is best hydraulic fluid to use in this machine? Right now we r using a napa brand AW**, forgot the viscosity.
It is easier to take the two out as one, a few hydraulic lines and engine hoses/wires, the whole assembily comes out. But you finally got the pulley free, so at least you got it out
I use engine oil, 15W40, I'm not sure what grade that is is hydraulic fluid though. AW46?
Well not the first time we did someting the hard way. lol. Do you know if I can put a pulley that is a little bit smaller or bigger in the hydro unit and run correctly? I broke ours pulling it and only used one I can find are 8.5" or 8.75" and ours seems to measure 8 5/8"...I would think smaller spin it a little faster giving it more hydro power at lower rpm? It has 6707583 on casting...It is easier to take the two out as one, a few hydraulic lines and engine hoses/wires, the whole assembily comes out. But you finally got the pulley free, so at least you got it out
I use engine oil, 15W40, I'm not sure what grade that is is hydraulic fluid though. AW46?
For that small difference, i don't see it being an issue, i'd try going a little bigger to give more torque, you'd probably never notice the difference.
The next issue is the drive belt, you will need one the correct length so you will have enough adjustment in it to get it tight.
How bad is the dealer for a new one?
Be very careful to inspect for broken bolt(s) that help hold the "charge" pump. On the 863's, they break off quite often & then hang down & can cause a horrible knocking noise. If it is broken, sometimes you can pull the rest of the bolt out with your fingers. These machines call for a special SPACER between the pump & engine mount. I would really encourage you to ensure that bolt & spacer is present when you get all done with her.
When u say charge pump, the one hanging off the rt side of unit or the internal? Also, the spacer your referring to is on the right side of the unit correct? Gettting a quote on the rebuild next tue/wed. so fingers are crossed its in decent shape and just needs a internal pump.
Guys, hydraulic pump guy got back with me...pump does have wear 1/1000th. He said other parts are worn but nothing spectacular given age/wear. Recommended rebuild and new relief valves, new suction hose, and clean the tank. BUT, he doesnt think its all the problem. He is leaning towards a drive motor being weak. Said something came through system and beat up the aluminum housing. One side of the machine wants to fight a little more than the other when the charge pressures get low, but other wise they are pretty equal. How hard are these things to pull? I don't want to put $3k into this and have it grenade and the have to redo...rather as much as it hurts, pull drives also. INsight is appreciated.
That doesn't seem like much wear to me either. Even with a bit of wear, they can still work pretty well.
I guess that is the risk you need to take, a machine can spit it guts out at any time, we just hope nothing will fail and do any damage.
If you were planning on keeping it, you can pull the motors apart and clean/inspect them. I'd also replace or sand the wear plates in the pumps.
As you were going to sell it, i'd just tell the prospective buyer that there are issues, and they will need to tend to it and decide how to proceed.
Ok, here is where we r at. Installed rebuilt hydro unit. Heritor pump plus gear pump etc...still have the hydraulic oil light come on?
Hotrod1830
Well-known member
- Joined
- Sep 14, 2010
- Messages
- 513
Pull the sending unit and install a gauge. The way I do it, if it is a problem when hot,(or intermittent) I will install a gauge and the light sender together with a Tee. That way the gauge and sender see the same pressure. get the unit hot until the light comes on. If the pressure is well above the minimum(set point for switch) You likely have an electrical problem .
Remember, High heat can effect electrical connections as well, so don't rule them out. But, as you have found, it is best to spend a little time/money to properly isolate the problem rather than throw part's at it.
Don't be affraid to ask the "mechanic" if you can see the gauge when it is hot/light is on
We spent over $500 at kc bobcat getting it diagnosed. That is where they wanted to start. I am a decent mechanic and can turn wrenches so we pulled it to save a few thousand dollars...it's more than a electrical/sensors problem b/c the steering sticks start getting stiff if we keep running it after the alarm goes off? I can put a gauge in it in the morning, but I believe this machine only has one? Tonight after watching it with the cab up and running, the right side drive motor takes about an .5" more movement at the pump while reversing than the left side but same amount of travel as the left side when going forward before movement?
