1990 Bobcat 753 Skidsteer

[Bill K]

Hello all, I am new to this forum and this is my first post. I recently purchased a 1990 Bobcat 753. The issues I am having are as follows:

I am getting an HP1 code on the BOSS system and the machine shuts off after approximately 45 seconds.

If I disconnect one wire going to the pressure sensor next to the hydraulic filter at the rear of the machine, the machine continues to run but I get the following error codes: HP1, HP2 and HP3, the machine stays running and moves forward and reverse as it should but still an issue with the lift and tilt.

The other issue I am having is the hydraulic Lift and bucket tilt work intermittently, sometime the lift and tilt goes up and down fast and other times it barley moves.

What do the two solenoids on the top of the control valve on the right hand side of the machine do? It appears I only have power to the green wire with the red tracer for the wire going to the forward solenoid with the key switch in the on position. I have disconnected these two plugs from both front and rear solenoids and the lift and tilt work a little better but not 100%

This is what I have done so far: I have changed the hydraulic oil filter and the hydraulic oil and the oil is at the full mark on the dipstick.

Any and all help would be greatly appreciated, Thank you all in advance, Bill

 

[brdgbldr]

I'm not overly familiar with 753 but I do know that most Bobcats have a brass filter encased in an aluminum housing.
I suggest going to bobcatparts.com and enter your serial number and then search for filters. I just looked at a random 753 and there were 2 of these filters shown.

 

[Bill K]

Thank you for the reply my bobcat is an early 753 and it did not come with those case drain filters but I did install two of them on the drive motor hydraulic circuit. I had the hydraulic issues before I installed the filters. So I'm not sure if I have a hydraulic pump issue or what is wrong with it.