Yanmar SA424 possible water contamination in Hydraulic Fluid

[Hulaballoo]

I bought a used Yanmar SA424 and immediately changed all fluids and filters. The tractor ran great all summer, but I was slow to address a small leak in one of the backhoe lines. I topped up the fluid in the fall, and noticed that the steering was stiff initially when cold, but would return to normal after the tractor warmed up. But in really cold weather, all of the hydraulics are stiff, bordering on non-functional.

I didn't have easy access to the yanmar branded TF500a, so went with the "equivalent" Mobilfluid 424, and initially thought that it might be too thick in cold weather. I just went out the garage to read the fine print from the nearly empty 5 gallon bucket, and when I lifted it I heard something solid slide across the bottom. I cut the seal, opened the bucket and found a good sized chunk of ice. My best guess is that the bucket got temporarily stored outside, water pooled in the lid, then leaked through the "handy" vent on top of the lid. I'm afraid that when I topped up the fluid (approximately 1 liter) I put in mostly water.

So a couple of questions...
1. What are the chances that I've damaged something?
2. Do these tractors have any ability to purge water from the hydraulic system? (I understand that I'll likely have to drain and refill, but even then there will surely be residual fluid)
3. Is a fluid change enough, or will I need to flush as well?
4. I imagine I should do both filters as well?

I appreciate your experience, as I am pretty new to tractors.

 

[agjones]

Good explanation of the situation, that helps a lot here.

Water can't leave the system without your help.

Probably no serious damage.

You'll likely need to work the remaining water through my changing filters and moving all the cylinders power steering etc.

Parker makes a filtration unit to run your fluid through to eliminate water. Sunbelt or United used to rent them. Not necessary. Flush, check, repeat will work

'Hydraulic filtration cart'

Source the right fluid for the tractor, enough to refill and drain. Water mixed in hydraulic fluid and aerated by use, makes it look a milk shake. When it's clear you've gotten it out of suspension (mix) but there could be a bit of water in the reservoir which for you is probably the trans-rear end housing. Bottom draining the fluid(sometimes there's more than one drain plug) should send most tank water out, jack the tractor up if necessary to get all you can.

Back to regular maintenance, deal with any seals, fittings or hoses that need attention and tractor on. They're tough and you caught it pretty fast in tractor years.

 

[BCLoco]

What do you mean by "really cold weather"?

As I'm sure you know oil and water generally don't want to mix, especially when they're in a static state such as in your oil bucket. So how much water, if any, was poured into the system seems like it would be minimal. But if water did get into the system, it won't remain separate from the oil. That's because in a pump driven system like the hydraulics on your tractor, the heat and pressure will cause them to mix, and emulsifiers in the oil will cause them to stay mixed. If there's enough water in the system to be worried about, the oil will show visible contamination. Usually a heavily clouded or even milky appearance.

It is possible that this tractor would be happier with a different oil, and by all means try replacing the oil if that will give you peace of mind. If you decide to replace the oil, you might as well replace the filters again so that you get full life out of this service.

In my experience, hydraulics in general are pretty sluggish and somewhat whiney below -10°C. I let the tractor run at a speed slightly above idle for at least 5-7 minutes after starting it in those temps. 10-15 minutes at -20°C and below. Keep in mind there's no combustion happening in that system to help speed up the warm-up, and it's a big reservoir. It takes time.

 

[Hulaballoo]

Thanks guys. I'd like to think that no damage has been done too, but a note in the operator's manual about operating a cold hydraulic system before adequate warm up time had me worried. I tend to be gentle on machines in general though; I've never even brought mine up to full rpms, so hopefully any effects of oil contamination would be minimized as I was only barely above idle when these symptoms presented.

To my eye, the oil in the sight glass does look somewhat less than perfectly clear, though certainly not like I've seen motor oil look after a blown head gasket. I'm a bit baffled that it operates so poorly when I suspect it has so little water in it. My initial estimate of 1L was surely a worst case scenario, since I doubt I added ALL water without noticing. What I mean by poor hydraulic performance is this: The steering will have essentially no assist, whereas normally it is comically overboosted, and all other features, from the backhoe stabilizer legs to the loader, will move when cold (at idle) but only barely, and they shudder as they move, as if sticking.

My plan is this: The machine has been parked on my sloped driveway for a few days, and as luck would have it, the drain plug (and thus low spot on reservoir) is pointed downhill. I'll crack the plug and drain about 1L of fluid out, just in case any water had settled to the bottom. Then I'll tighten the plug, and run the tractor until warm, to suspend the rest of the water in the oil. I'll then drain the remainder, and pull the filters. I'm tempted to drain the filters as best as I can, then reinstall them, at least temporarily. New ones will need to be ordered, besides, I will probably wind up flushing out the new oil before long, and I think there's more water in the hydraulic cylinders (that I can't get out) than the filters anyhow. After I (gently) run the thing for a while, and have new filters on hand, I'll purge and re-fill one more time.

What do you guys think? Also, any ideas on getting as much oil out of the implements as possible? Any chance that propping the loader/backhoe/stabilizer legs up mechanically, then manually exercising the cylinders with the engine off and the drain plug removed might bring more oil down into the reservoir?

Thanks again

Oh, I'm in Northern Colorado. It was probably just a few degrees below freezing when I ran it before, but will get significantly colder in the upcoming days, hence why I intend to drain today. It will hit -11F (-24c) this weekend, and occasionally will get colder than that, though not normally. Your advice for warming fluid closely mirrors the owner's manual.

 

[agjones]

The more filters you go through here the better you'll feel about the outcome

You can totally manipulate this cyls manually. They'll take a little grunt and then mooooove. So be aware of its path and pinch hazards... The fluid will kinda blast out of the house at first...You can set up a drain pan cover (towel and rubber band or clamp like a diffuser) and clamp the hose from an implement cylinder and manually move it. That way the hose end is secured, flow contained and you have both hands free.

Cylinders can purge a little air on their own. Motor implements kinda the same process if you're able to turn the blade to move the motor a couple revs.

The steering circuit (and the stuff attached to it) is the most sensitive to air, water in my experience.

If anything for the amount of run time since this happened.... Maybe you pushed a seal out somewhere with thick cold fluid. You didn't likely boil the water in the system and cause cavitation (bubble and pressure) damage to the hard parts.

 

[BCLoco]

Thanks guys. I'd like to think that no damage has been done too, but a note in the operator's manual about operating a cold hydraulic system before adequate warm up time had me worried. I tend to be gentle on machines in general though; I've never even brought mine up to full rpms, so hopefully any effects of oil contamination would be minimized as I was only barely above idle when these symptoms presented.

To my eye, the oil in the sight glass does look somewhat less than perfectly clear, though certainly not like I've seen motor oil look after a blown head gasket. I'm a bit baffled that it operates so poorly when I suspect it has so little water in it. My initial estimate of 1L was surely a worst case scenario, since I doubt I added ALL water without noticing. What I mean by poor hydraulic performance is this: The steering will have essentially no assist, whereas normally it is comically overboosted, and all other features, from the backhoe stabilizer legs to the loader, will move when cold (at idle) but only barely, and they shudder as they move, as if sticking.

My plan is this: The machine has been parked on my sloped driveway for a few days, and as luck would have it, the drain plug (and thus low spot on reservoir) is pointed downhill. I'll crack the plug and drain about 1L of fluid out, just in case any water had settled to the bottom. Then I'll tighten the plug, and run the tractor until warm, to suspend the rest of the water in the oil. I'll then drain the remainder, and pull the filters. I'm tempted to drain the filters as best as I can, then reinstall them, at least temporarily. New ones will need to be ordered, besides, I will probably wind up flushing out the new oil before long, and I think there's more water in the hydraulic cylinders (that I can't get out) than the filters anyhow. After I (gently) run the thing for a while, and have new filters on hand, I'll purge and re-fill one more time.

What do you guys think? Also, any ideas on getting as much oil out of the implements as possible? Any chance that propping the loader/backhoe/stabilizer legs up mechanically, then manually exercising the cylinders with the engine off and the drain plug removed might bring more oil down into the reservoir?

Thanks again

Oh, I'm in Northern Colorado. It was probably just a few degrees below freezing when I ran it before, but will get significantly colder in the upcoming days, hence why I intend to drain today. It will hit -11F (-24c) this weekend, and occasionally will get colder than that, though not normally. Your advice for warming fluid closely mirrors the owner's manual.

Personally, I'd rather just continue to drain and refill with new fluid, and cycle the hydraulics until I felt any contamination that may have been present, was under control. Manually purging at least 9 cylinders sounds awful, though no doubt it's the more thorough and affordable method.

I'm skeptical that water contamination is the issue, but completely agree that the symptoms sound more severe than my own experience with a cold hydraulic system. Replacing the fluid with good factory spec stuff is a logical first step.

I'll pay more attention to how mine reacts cold this Sunday. It's going to be in the -20s, so should be as good a comparison as any.

 

[Hulaballoo]

Racing a cold front, I started work before receiving suggestions. I didn't consider, removing hoses, but probably would have tried my simpler way first anyhow. When cracked, the drain plug initially released what was probably 1 tablespoon of water, then another cup of two or diluted oil. I recapped as planned, then started the tractor and let it idle for 5 minutes or so. I raised all implements to their max elevation, shut the tractor down and drained about 4 gallons of what looked a lot like homemade carmel. Mmmm. I had a small helper hold valves open while I moved implements around, which got very heavy without the assistance of hyd fluid to hold them up, but which had the desired effect of re-starting the flow of fluid into the drain bucket. I removed and drained the filters, then reinstalled. I've got 5 fresh gallons of Traveller brand (J20c compliant) fluid staying warm indoors, and hope to go outside this afternoon to pour it in.

The fluid seemed to have more water in it than I was expecting. It'll take some time to get it out, but I'm hoping that the contamination level of this fluid change is light enough that I can feel good about getting a little use out of it before flushing again. next time I'll put the whole machine on stands so perhaps I can cycle the steering system and maybe even manually turn the wheels while holding the drive pedals.

Now to re-fill. It occurred to me while draining that there is a tremendous amount of air in my system that will need to be purged. I know the tractor has some ability to get this air out itself, but I've given it an extraordinary job to do, so hoping it's up to the task. There is a a not in the manual about wanting to wait after applying new fluid to let it settle before starting it up. I'll balance that with wanting to still have the fluid be warm when I start it.

After that I'll verrrry slowly operate valves to attempt to gently fill cylinders, then repeatedly cycle them to clear the air and mix all of the old oil with the new. How does that sound?

If you think of any other suggestions I'm all ears.

Sean

 

[Hulaballoo]

Here's the just-drained oil sitting in the bucket.

 

[msb1766]

Give this dealer a call about the T500a hydraulic fluid, I got a 5 gallon pail from them during COVID, they were great to deal with.
I could not fid it anywhere then.

Cub Cadet Parts, Cub Parts, Troy-Bilt Parts, Zero-Turn Parts and MTD Parts

 

[BCLoco]

Racing a cold front, I started work before receiving suggestions. I didn't consider, removing hoses, but probably would have tried my simpler way first anyhow. When cracked, the drain plug initially released what was probably 1 tablespoon of water, then another cup of two or diluted oil. I recapped as planned, then started the tractor and let it idle for 5 minutes or so. I raised all implements to their max elevation, shut the tractor down and drained about 4 gallons of what looked a lot like homemade carmel. Mmmm. I had a small helper hold valves open while I moved implements around, which got very heavy without the assistance of hyd fluid to hold them up, but which had the desired effect of re-starting the flow of fluid into the drain bucket. I removed and drained the filters, then reinstalled. I've got 5 fresh gallons of Traveller brand (J20c compliant) fluid staying warm indoors, and hope to go outside this afternoon to pour it in.

The fluid seemed to have more water in it than I was expecting. It'll take some time to get it out, but I'm hoping that the contamination level of this fluid change is light enough that I can feel good about getting a little use out of it before flushing again. next time I'll put the whole machine on stands so perhaps I can cycle the steering system and maybe even manually turn the wheels while holding the drive pedals.

Now to re-fill. It occurred to me while draining that there is a tremendous amount of air in my system that will need to be purged. I know the tractor has some ability to get this air out itself, but I've given it an extraordinary job to do, so hoping it's up to the task. There is a a not in the manual about wanting to wait after applying new fluid to let it settle before starting it up. I'll balance that with wanting to still have the fluid be warm when I start it.

After that I'll verrrry slowly operate valves to attempt to gently fill cylinders, then repeatedly cycle them to clear the air and mix all of the old oil with the new. How does that sound?

If you think of any other suggestions I'm all ears.

Sean

To my eye, the oil in the sight glass does look somewhat less than perfectly clear,

Holy geez man that oil is not "somewhat less than perfectly clear", as you put it lol. Yeah that's a lot of water contamination. My initial skepticism about water contamination was based on your description of the oil. A picture is worth a thousand words.

As muddy as that looks, I doubt you've done too much harm to the machine. I would let it get fully warm and fully bled between fluid changes (I'm sure you'll need to do at least one or two more). The best way on a hydraulic system to get all the air out, is to give the fluid time to expel the air before cycling more fluid through a cylinder or motor. Every time an operation dumps aerated and slightly frothed fluid into the reservoir, give it time for that air to all rise to the top of the reservoir, or the pump will be sucking aerated fluid and sending it back to the consumers. This will greatly increase the amount of time it takes to get the system properly bled, as well as how much air your pump needs to deal with.

Something like 10-15 minutes of running it to get everything warmed up, then fully stroke one cylinder in one direction only, and let the system run for another couple minutes. Then fully stroke that same cylinder in the opposite direction, and again let the system run for a couple minutes. Repeat for all cylinders, one function at a time. The hotter the fluid is, the faster the air bubbles can rise to the surface and exit the fluid.