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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 5570
Experience:  Owner at DJ Wilson
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I have a 2005 jcb mini cx backhoe, it keeps leaking

Customer Question

I have a 2005 jcb mini cx backhoe , it keeps leaking hydraulic fluid out of the vent on top of the reservoir , the vent cap on jcb seems to be a check valve of some sort, I installed a new one oem from jcb and installed new hyd. filter and filled with proper fluid to level in sight glass, all hydraulics work great, just keeps pushing fluid out vent, then gets on exhaust and makes a mess and smokes like a freight train, HELP
JA: Sometimes things that you think will be really complicated end up being easy to fix. The Heavy Equipment Mechanic I'm going to connect you with knows all the tricks and shortcuts.
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Customer: no
Submitted: 2 months ago.
Category: Medium and Heavy Trucks
Expert:  Daniel Wilson replied 2 months ago.

Hi my name is***** will be glad to help. With the oil at operating temp does it go above the sight glass? I want to be sure it is not just slightly overfull and there is air space at the top of the tank. Also what position are all your attachments when checking the level?

Expert:  Daniel Wilson replied 2 months ago.

Please post the full model and serial number of your machine.

Customer: replied 2 months ago.
the owners manual says travel position loader bucket off ground 12 inches and curled back, and hoe folded up , 2005 jcb mini cx backhoe slpmbh025e1042384
Customer: replied 2 months ago.
it is in the sight glass , i have tried below and above sight glass , messin with it a couple years
Expert:  Daniel Wilson replied 2 months ago.

I thought actually it was hoe folded up and the loader bucket and cutting edge flat on the ground. If that is right then it could be the extra oil from the cylinder when lowering the bucket to the ground position coming out of the vent.

Customer: replied 2 months ago.
I double checked owners manual and it states as I described
Customer: replied 2 months ago.
I have made sure the cooler is clean, fan belt is tight , fluid is clean and not foamy
Expert:  Daniel Wilson replied 2 months ago.

The oil level always rises after operating temp so the middle of the glass is best. Are there any other operational issues with this machine?

Expert:  Daniel Wilson replied 2 months ago.

If there is not a problem with the level and air space top of tank then the only other thing I can think of if a problem with pressure bypassing somewhere to the return side of the system.

Customer: replied 2 months ago.
the machine operates great, just messy, the vent cap from jcb you can not blow through it , there is a spring with a rubber diaphragm in it, and pricey, a typical vent cap on other hydraulic systems, I can blow through and they in expensive, closed system?
Customer: replied 2 months ago.
if I operate machine for a while what should fluid temp be
Expert:  Daniel Wilson replied 2 months ago.

The hydraulic system takes a while to come up to operating temp is below 180f. Anything above that will break down the oil and will start to cause problems.

Expert:  Daniel Wilson replied 2 months ago.

Yes you are correct. I just checked as well and the outriggers must be retracted as well and boom to the side position.

Customer: replied 2 months ago.
I did not see where it says check it cold or hot
Expert:  Daniel Wilson replied 2 months ago.

It does not. I am speaking from experience. I always go the middle of the glass cold if hot maybe 3/4 up

Customer: replied 2 months ago.
it seems as though the fluid is returning back to the tank violently, is there some sort of defuser
Expert:  Daniel Wilson replied 2 months ago.

That is what I suggested earlier.

"If there is not a problem with the level and air space top of tank then the only other thing I can think of if a problem with pressure bypassing somewhere to the return side of the system."

If this is the case it is an indication of a component problem allowing pressure to the return side. further testing of return and case drain pressures would be needed to isolate this.