450C weak hydraulics.

deepsouthoutdoorsman · Jul 30, 2019

I have a new to me 450C loader. I bought it knowing the hydraulics are weak. Boom wont even lift unless at high rpms. So I purchased a pump for it thinking it was the pump. Same thing. No hydraulic pressure. Every control is the same way. So I drained the tank. New return filter. Cleaned the suction screen. Refilled to half way is sight glass. Still same thing. Weak pressure. I removed the pump again and checked the coupler splines and they are good. Is there a Main releif valve on the system they may be stuck open not allowing any pressure to build? If so where or which valve body would it be in?
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AJ. · Jul 31, 2019

Yes all hydraulic systems will have a main relief valve and each function will have an auxiliary valve commonly called a port valve,the main valve is set lower than the auxiliary valves so it will open before them,your problem points to the main valve,it can be stuck open,the seat is bad or the most likely thing is the o'rings on the valve body,look at the loader control valve,you can have a two spool or three spool or even more depending what equipment is fitted,4 in 1,ripper etc,usually it's the same valve with more or less sections,see the parts drawing I've uploaded where I have the ring,that is the main valve,all the equipment safely on the ground,wobble a lever to let the pressure go loosen the tank cap and remove the valve and see what you find,keep things clean.
AJ

deepsouthoutdoorsman · Aug 14, 2019

Thanks AJ got the main relief valve changed (couldn?t figure out how to take old valve apart to clean and
inspect). Hydraulics like new. Thanks for your time and information.
David

450C weak hydraulics.

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AJ.

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