Ford 6600 Hydraullic Overheating

I have a new-to-me ford 6600 dual power 4wd, with a loader with around 5000 hours on it (estimate, hour meter has been changed) I purchased it from a neighbor who ran it minimally the last 15 years. the only known issue is the 4wd will not disengage (hydraulic clutch, might be a pressure issue with the valve?) Not a big concern to me.

After a brief go-through, I ran it mowing pastures for around 5 hours, including some hills. This revealed a few small things, such as a bad water pump, some small hydraulic gasket leaks.

I changed the water pump, and all the fluids and filters at that point. There was some fine metal in the hydro fluid, though it was running with no issues. Its hard to say when it was last changed, so not too worried there. It was pretty dark. Replaced fluid with Napa premium heavy duty, which meets M2C134, should well exceed needed specs. Baldwin Filters. I also removed 2 auxiliary valves from the loader that were used for a bale grapple.

This weekend I went and picked up a couple implements from him, and ran the tractor for a couple hours. On the way home, I noted the hydraulic valves and rear end were getting hot to the touch, almost too hot to touch. everything remained functioning normally. I am curious if anyone has experienced this before, I am wondering if it is something catching in the cooling circuit valve (oil cooler was removed and cleaned when i did the water pump) or ?

Any thoughts appreciated. I removed the loader last night to see if I can remove that variable, I'll go for a bit of a drive today. I also plan to change the fluid and filter again to flush things out good.

Thank you!

Make sure your remote valves are in neutral. If they're stuck in the raise or lower position, with nothing in the rear couplers, you'll heat up the oil quickly.

4WD disengagement issue could be crap built up under the lever linkage on the transfer case - common problem.

You ran it for five hours one day with no heating problems. Then one day (after a few repairs) it starts heating the hydraulics after only two hours.

My first thought goes to the valve you removed, where it was, how it was plumbed in, and how is the plumbing now?

(quoted from post at 17:51:08 01/24/23) You ran it for five hours one day with no heating problems. Then one day (after a few repairs) it starts heating the hydraulics after only two hours.

My first thought goes to the valve you removed, where it was, how it was plumbed in, and how is the plumbing now?

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I agree- that seems to be the most obvious. The tractor has a loader plumbed on via an auxiliary hydraulic stack placed under the two usual valves. This runs a pressure line to the two loader spools, from there a port took power to the second valve set (2 more spools) for the grapple. Both the out of the 1st 2 spools and the second two spools connected, and returned to the tractor valve. I wonder if the pressure reg on the second was doing bypass duty for both manifolds.

When the loader is removed, the two lines (in and out) are connected to make a circuit. I ran it a bit tonight with the loader off, and it didn't heat up quickly at least, but the hydro does seem a bit whiney.

They are both in neutral- the 4wd lever is moving freely- it is something internal. I can feel the end of the stroke but nothing changes, if that makes sense.

This post was edited by Delta456 on 01/24/2023 at 05:23 pm.