6610 Dual Power/Low Pressure Circuit Update

Got the top cover off the 6610 this morning and got everything redirected into the sump (after makeing quite a mess the first attempt...)
And it was holding just around 150 psi cold. Went ahead and tore everything apart I needed to in order to get the PTO brake band replaced
(20ft batwing and it getting shut off at full throttle do wonders for those little bands). I pulled both relief valves on the PTO valve
body out and cleaned the bores, put them back. I replaced the o-ring on the supply tube with a metric 3mm CS 12mm ID which is slightly
thicker than a -112 o ring the manual calls for. It sealed in perfectly, took away a lot of the slop, and the clip pin still clipped in
the groove. So anyone who comes across this, it seems to work very well upon first test.

Anyways, put everything back together, fired it up, ~160 psi at idle. I took a screw driver while it was running, and pushed in on the
washer stack for the relief valve, and the pressure increased. I went and grabbed a couple more washers and added them to the relief
valve, and now I have 180-185 psi cold (I know spec calls for 160-180). When idled up with cold oil, it climbs to ~225 psi. Is there
anything wrong with leaving it shimmed where it is? I feel like it's been said before it's better to have them shimmed to the high end if
you're working on them.

I still am having issues with the DP valve sticking. The old brake band was missing about half the lining, and the dual power discs on the
direct side were missing most of the brass lining, and I have found both of those things floating around after changing the oil and
filters. Would it be a good idea to run diesel in the rear end compartment for a few minutes stationary to try and flush all the debris
out? Or am I better off doing a short oil and filter change?

Hurst

I don't think you did yourself any favors by shimming that valve spool. The spec of 160-180 is with hot oil, not cold. Get that oil good and warm and I suspect you'll be right back where you started.

Pouring diesel through the rear axle might make you feel a little better when you're done, but will do little to flush out the debris.

Sorry to be a Debbie Downer on this one.

I did leave out in the first post that I believe the supply tube was not sealing well. There was a good stream coming down the tube while running. It looks like some is always coming down the side of the PTO valve from the relief valve weep hole. It looks like about half as much oil as before. I think I have a magnetic oil pan heater around, I may put it on the bottom of the housing and see if I can at least get the oil above 100 degrees and see how my pressures change. I doubt I'll get it very hot with everything diverted back to the sump, and I know it's hard to get great readings with cold oil... One of the reasons I wanted to shim it up to the higher side, I figured it wasn't going to go higher as the oil got warmer.

Any suggestions for getting the debris out? Just keep changing fluid and filters? The piece I found last time matched what was on the original direct drive plates. I'm hoping to get the spool off tomorrow and see what I find in it this time, but imagine it will be more debris. I'm still skeptical of the pump being and issue. It doesn't have more than 3-400 hours on it at most. That being said, I haven't ruled it out yet, just trying to get everything else checked before I start throwing parts at it.

Hurst

Ohh, and for anyone reading this in the future... DO NOT accidentally turn on the PTO while you're hanging your head over the top cover opening... It's a great way to get an oil fascial

Hurst

If you believe the supply tube was leaking past the o-ring, then maybe you've found your problem, or at least part of it. Still, you're not out of the woods until you can maintain 160-180 PSI with hot, or at least warm, oil at idle. Trying to heat the oil with a pan heater is pretty much useless, unless you had 3 or 4 of them.

I tell you what I'd do if this was my tractor, based on everything I know. I'd pull the main hydraulic pump out and clean out the debris hidden underneath and behind it. At the same time I'd remove the rear section of the pump and inspect the PTO portion of it. If it looks OK, put it back together, you've lost nothing except a little bit of time. There's certainly no need to throw parts at it.

Also, I'd strongly consider removing the RH final drive and cleaning out the rearmost section of the rear axle. I'd bet a lot of your debris is laying back there. It'd be a lot of work, especially if you have heavy tires and a roll bar, but would be worth it to get a lot of that crap out of there.

Got everything back together tonight and ran a remote open at idle until the hydraulic lines were hot to the touch. Low pressure side maintained 170 psi. I put it back in the barn and shifted the dual power, and it is much more crisp than I remember and very quick shifting. I need to get some more oil to make up for what I lost from having the top cover off and my diversion tube coming loose. Once I get that done, Im going to try and put it to work and get the oil good and hot and monitor the pressure before I take off the pressure gauge. Thank you for the help! Hopefully Im done asking questions about this tractor for a while!

Hurst