Need some hydraulics help

[PlanMan]

I have a B7200 with FEL, with 325 hrs. on it. I bought it from a trusted individual last year and have put 75 hrs. on it without any problems. The previous owner was a retired mechanic who kept the machine serviced well.

Yesterday after starting it and letting it warm, I went to raise my brush hog and nothing happened. I raised and lowered my FEL and then the 3 point lift worked fine, raised all the way and held. But.... I was using the FEL to move some gravel and noticed the hydraulics weakened when the engine RPM's went down. For example, I had a full bucket of gravel, was backing away from the pile, and as the RPM's slowed while I was shifting from reverse to first gear, the bucket began to roll forward, almost dumping the load, even though I quickly pulled the control lever, until I stepped on the accelerator, at which point it regained power and I was able to roll it back up.

Could this be caused by a dirty screen in the hydraulics or might I be looking at a pump problem or a leaking valve body.

Thanks in advance.

 

[DieselPower]

Not to sure about the non lifting hog but if your bucket is rolling it sounds like the valve is not centering properly or a leaky valve body. Does the FEL and 3 PH go down to?

 

[PlanMan]

Thanks for the reply. No, the FEL does not lower or leak down on its own, and the mower stayed up all afternoon at any RPM.

Not sure how PA has been but have had rain for days on end, and the temp. has gone from 70 degrees Tues. to snow today. I had not used the machine for weeks, and it is stored outside right now, but I do have a cab. I am wondering if condensation has played a part.

 

[MadReferee]

I vote for the loader valve. If the spool is slightly engaged fluid will flow to it rather than continue on to the 3pt. When you see a bucket drop like that then you can almost be sure the spool has problems.

 

[PlanMan]

Would the flow diversion explain why the 3ph would not not raise until I operated the loader?

This has me thinking about the valve lever - I just recently put my side curtains back on the cab for winter (sims cab) and they are drum tight, including the slot where the loader lever comes through, as the valve body is outside the curtain. Could slight pressure on the base of the lever from the side curtain, but not enough to operate the loader, cause this?

 

[MadReferee]

Would the flow diversion explain why the 3ph would not not raise until I operated the loader?

Yes, it could.

This has me thinking about the valve lever - I just recently put my side curtains back on the cab for winter (sims cab) and they are drum tight, including the slot where the loader lever comes through, as the valve body is outside the curtain. Could slight pressure on the base of the lever from the side curtain, but not enough to operate the loader, cause this?

The cab installation would be the first thing I would investigate since it seems that the problem started soon after you installed the cab.