First thing i want to say is this forum has been a great help to me but i cannot find any thread on the forum or info in my operators manuals that addresses my issues. I only have 2 questions and both are with the hydraulics. Serial# *7PS01136* ?#1 Does the hyd fill cap vent pressure from the system while in operation,, i see the hole drilled in the cap but the rubber washer blocks the vent hole and causes the system to hold pressure for days. its pressure not a vacuum. ?#2 I noticed on the CAT web site that there is a strainer in the hyd tank is this something that needs to be replaced ,cleaned or just leave it alone. Im not having any problems with the hyd just changing all the fliuds getting the dozer ready for work.
The cap should hold pressure theres a valve on the tank that sorta looks like a compressor relief valve thag will regulate the tank pressure to 5 or so psi. As for the screen its most likely ok I dont believe theres a maintance intervol on it
OK , THANK YOU
Confirming what Tyler said. The tank needs to maintain a few psi of pressure to assist with the flow of oil into the implement hydraulic pump suction port. If you do all your own maintenance your best bet would be to get hold of an Operation & Maintenance Manual for your tractor. The Cat Publication reference is SEBU7077 and you can download a pdf copy for $52 from HERE Simply put SEBU7077 in the box and click Search. IiRC the strainer in the neck of the implement hydraulic tank should be washed in some sort of solvent and dried every time the oil is changed. The same goes for the pressure relief valve. I'll find a parts drawing of the tank plus the oil change procedure. The tank breaker relief valve opens at 18psi under pressure. Generally if there is a vacuum in the tank of only a couple of inches of water the valve will also open to prevent serious vacuum being created.
If you have pressure when removing the cap is good. Generally means you don't have any oil leaking on the suction side. I'm always relieved when I have to let the cap vent when removing it. I have some cylinders weeping a bit though so have to top up the fluid occasionally.