CAT 416 Boom weak? Cyls? Valve? Oil?

Jeff Hoo · Jul 26, 2011

90's Backhoe, lightly used.

All other hydraulics seem to work fine, but the boom lift cylinders suddenly barely have any oomph.

If the arm is even half extended, they can't even lift the boom.

How do I tell if this is a cylinder/piston leak? Or spool valve problem? Or maybe bleed or fluid problem. Need higher weight oil?

Using Valvoline AW32 hyd fluid now (100F here, too)

Thanks
Jeff

AJ. · Jul 27, 2011

By the rule of thumb if the cylinder seals are letting the oil bypass the boom would start to drop when you let the lever go,if the boom holds up it is more likely that it is a valve issue,check that the linkage is moving the spool the right amount,if it drops it only takes the seal in one cylinder to cause it,it is best to reseal both cylinders.
AJ

Anonymous-0 · Jul 27, 2011

Try working another circuit(bucket closed) with boom lift and see if it comes to life. If you lose the seal on the ball resolver there is no signal to upstroke the pump. Another circuit will override that.
Later Bob

jm. · Jul 29, 2011

We have been abel to operate the unit to get the temp up on working cylinders then take an infered thermoter and check temps. The one with the high operating temps will be the one that is bypassing.

CAT 416 Boom weak? Cyls? Valve? Oil?

Jeff Hoo

New User

AJ.

Well-known Member

Anonymous-0

Well-known Member

jm.

Well-known Member

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