Frozen Hydraulics DB 990

[mennometis]

It takes forever for my hydraulics to become usable below -10°C. Right now I have to run the tractor and point a heat gun at the valves for several hours before it starts working. Tractor starts great even at -25°C if plugged in overnight. Restriction light is ON so maybe a filter replacement will help, or is there another reason why these hydraulics are poor in cold weather? Tractor is a 1974 Case DB 990, my chore tractor.

 

[Tgrasher]

Cold thick oil plus a restricted filter would make for a slow response. Not familiar with where your filter is located ie. whether oil must be drained or not, but cleaning or replacing it would be the easiest fix.

 

[DoubleO7]

water contaminated?

 

[mennometis]

I'm guessing combination of both old filter and water in oil as you both say. Assuming I have no place to warm up oil, anyone try a magnetic pan heater and have any recommendations?

 

[Joe Stewart]

Why don't you start by changing the oil and filter? Note that the 990 has two drain plugs for draining the hydraulic fluid. Open them both to remove all contaminated fluid. Replace the gaiters on your shift levers so no more water gets in. And yes, with temperatures like the one you mentioned, I would expect that viscosity is playing a role here. Will a dipstick heater fit? I've never tried one on my 990s, since the temps around here rarely get below 20 degrees fahrenheit. Did the hydraulics work well over the summer months? Do you have a loader plumbed into this system?

 

[mennometis]

Yeah it has a loader that works great in summer, but lots of rain this year and one of my shift lever boots is cracked. Took 5 hours to warm up today after a -25C night. I switched to only round bales this year so it needs to work. Don't feel like climbing under there at -20C outside to make a mess and not sure an ice cube in the sump will drain.

 

[mennometis]

By the way viscosity is not so bad that I can't lift the loader arms all the way and back down again...once. It won't lift a second time. I don't know the circuit, but I'm probably starving the pump after I use post-filter available oil.

I bought a Kat's magnetic heater and can't tell if it helped since it is now 20 degrees warmer and it all works great.

 

[mennometis]

So the 200W (300F) Kat's heater on the bottom of the sump for 12 hours didn't help.
I still get just enough oil to fill the loader arm cylinders once. It can't be just a viscosity issue.
What's preventing more than a couple gallons of oil from getting to the pump?

 

[Joe Stewart]

Perhaps water got into your oil pick up tube and froze. See the following thread and note RG Martin's response.

Case 990 hydraulic problem

Hello, I have been working on my case/David brown hydraulic system. I couldn't get the lift arms or front end loader bucket to work . I have finally found a major part of the problem, there may be other pieces to the puzzle that are yet to be discovered. The previous owner had hyd problems ...

forums.yesterdaystractors.com

 

[Jim.ME]

Filter restriction light on, pretty much sounds like water icing in the filter when cold. The filter is marginal to start and gets further plugged as it runs for a short time. Rain and cracked shifting boots are a recipe for water contamination, especially if it sets outside at times. depending on the surface area the 200-watt heater may not be doing much as the heat it makes is dispersed through the transmission case as well as the oil inside. Several magnetic heaters may be required to do the job, 600 to 1000 watts more likely. What does it have in it for oil? Not running it enough to warm the oil can make the problem worse as well.

Sorry, but your post "Don't feel like climbing under there at -20C outside to make a mess and not sure an ice cube in the sump will drain." says you know the fix for this, but you are just hoping for a silver bullet. Rent or borrow a good-sized space heater, tent it and heat it up good. It may take a couple oil and filter changes to clear it, along with new shift boots. A small tarp over the operator's area can help keep water out as well when setting.

 

[mennometis]

I'm just curious where the 2 gallons of usable oil to fill cylinders is coming from? I sure would like to see a hydraulic schematic of the system supplying the remotes.

 

[Jim.ME]

I'm just curious where the 2 gallons of usable oil to fill cylinders is coming from? I sure would like to see a hydraulic schematic of the system supplying the remotes.

The oil for the remotes is going to come from the reservoir, which I am guessing is the transmission case of your tractor. That schematic should be in the service manual, do you have the correct one for your tractor? If not, you should invest in one.

The filter may partially clear as it sets and allow enough fluid to pass to do that before it plugs again, with ice crystals, I am guessing. doing the proper service may give you more answers than what "iffing" it. Sometimes you just have to bite the bullet and do what you don't want to, at a time not to your liking. I'm outside at 20F doing something I'd rather not be doing at this temperature, but it needs to be done. It quitting when it is below 20F, snowing, and the wind blowing could be the alternative, it was an easy choice for me.

 

[jean claude marleau]

Check your remote valve on the rear right hand side. , most of the hydraulic problem comes from that valve if your oil filter and oil is nice. jc

 

[LPakiz]

I had similiar things happen to my old Big 400. The hydraulics would work for a few minutes, then get slower and stop.
The problem was water in the oil. When warm, oil could enter the suction filter just fine but when the water froze, ice crystals would plug the filter, starving the hydraulic pump.
I took the filter right out one winter and the problem was solved.
The long fix was just as several folks advised--change the oil and don't let any more rain/water into the system.

 

[mennometis]

Check your remote valve on the rear right hand side. , most of the hydraulic problem comes from that valve if your oil filter and oil is nice. jc

What do I check on that right rear remote valve? Finally got cold enough to test my oil and filter change. Same problem, but didn't run it more than half an hour. When I replaced oil and filter, I drained case and diff. Also extended cylinders before change and then retracted/drained them fully during change. Also drained all hoses on the loader all the way to remote couplers. They say Masseys are bad, but my MF65 outperforms this 10 years newer 990 in cold weather every winter.

 

[mennometis]

Well, made it through winter. There was enough oil available on the pump side of the filter to lift and lower 3 or 4 bales every weekend before it ran out of available oil. If I had to use the snowblower, it helped get it warmer sooner when I needed to use the hydraulics more than that.