Milky hydraulic fliud.

Boss 302 · Dec 8, 2021

Sounds like air to me, like said drain it in a clean bucket and see if it clears up

rScotty · Dec 9, 2021

The milky look is caused by either air or water. No, mixing different types of trans/hydraulic fluids doesn't cause that.

To determine which it is - air or water - check it in the morning before starting. If it is air (micro bubbles) it will have cleared up noticibly.

If it is water it will eventually turn slimy, change fluid a few times and don't leave it out in the rain without a tarp.

If air, you have a suction leak between the sump and the high pressure pump. Usually it's a fitting, but can be around a filter.

Good luck.

rasorbackq · Dec 9, 2021

Dont understand the air sucking comments.. The filler cap has a hole in it to allow air in . Its is U shaped so pointing down.
If it is a fitting leaking air . shouldnt it leak when parked??
I will check out the filters again . Need the tractor today to clear snow. First snow fall for the year . Only 5-6 inches.

rScotty · Dec 9, 2021

rasorbackq said:
Dont understand the air sucking comments.. The filler cap has a hole in it to allow air in . Its is U shaped so pointing down.
If it is a fitting leaking air . shouldnt it leak when parked??
I will check out the filters again . Need the tractor today to clear snow. First snow fall for the year . Only 5-6 inches.

Fair question. So here we go...Good call on the vent. It really is the key.

The vent in filler cap does two things: Most important is that it allows some air into the sump cavity to replace the reduced fluid volume of in the sump which happens when some of the fluid in the sump is initially moved up into the hydraulic pump. Allowing the air to enter via the vent maintains the atmospheric pressure in the sump. Since the high pressure hydraulic pump is above the level of the fluid in the sump, that atmospheric air pressure is necessary because ultimately that atmospheric air pressure is what forces fluid up to the high pressure pump.
The high pressure pump helps to suck fluid up to itself because when the pump starts to spin it reduces the pressure in its intake line. We call that "suction". but technically it is just different pressures...when the pump spins, air pressure in the sump is higher than the pressure at the intake of the pump, and that higher pressure forces fluid up to the pump.

Now if there is anywhere along the line between the sump and the pump where air can sneak in, then it will. That is called a suction leak. Sometimes it is a tiny split in the end of a hose between the sump and the pump. But can be anywhere. The result is that the pump tries to compress the air into the oil and that makes these microbubbles that make the fluid look cloudy. And just as you say, with a suction leak you won't see any oil leaking out externally until you turn it off. That's because air is being sucked in while it is running. But sometimes when the engine is shut off and just sitting there the suction leak will declare itself by dropping some oil out as the pump's oil slowly returns to the sump because of gravity.

I said that the air vent in the filler cap does two things. Replacing air in the sump is one more thing. The other is that it allows air to flow in and out of the sump as the sump and fluid heats and cools.
Both functions that the air vent does are aimed at maintaining a constant atmospheric pressure on the fluid in the sump.

Does that help?
rScotty

woody · Dec 9, 2021

Mine was a bad seal on the pump and it did not leak a drop. That being said I don't believe it's your pump must be something you changed or cleaned or maybe over tightened, hopefully yours will show itself in the form of a small leak.

rasorbackq · Dec 9, 2021

rScotty said:
Fair question. So here we go...Good call on the vent. It really is the key.

The vent in filler cap does two things: Most important is that it allows some air into the sump cavity to replace the reduced fluid volume of in the sump which happens when some of the fluid in the sump is initially moved up into the hydraulic pump. Allowing the air to enter via the vent maintains the atmospheric pressure in the sump. Since the high pressure hydraulic pump is above the level of the fluid in the sump, that atmospheric air pressure is necessary because ultimately that atmospheric air pressure is what forces fluid up to the high pressure pump.
The high pressure pump helps to suck fluid up to itself because when the pump starts to spin it reduces the pressure in its intake line. We call that "suction". but technically it is just different pressures...when the pump spins, air pressure in the sump is higher than the pressure at the intake of the pump, and that higher pressure forces fluid up to the pump.

Now if there is anywhere along the line between the sump and the pump where air can sneak in, then it will. That is called a suction leak. Sometimes it is a tiny split in the end of a hose between the sump and the pump. But can be anywhere. The result is that the pump tries to compress the air into the oil and that makes these microbubbles that make the fluid look cloudy. And just as you say, with a suction leak you won't see any oil leaking out externally until you turn it off. That's because air is being sucked in while it is running. But sometimes when the engine is shut off and just sitting there the suction leak will declare itself by dropping some oil out as the pump's oil slowly returns to the sump because of gravity.

I said that the air vent in the filler cap does two things. Replacing air in the sump is one more thing. The other is that it allows air to flow in and out of the sump as the sump and fluid heats and cools.
Both functions that the air vent does are aimed at maintaining a constant atmospheric pressure on the fluid in the sump.

Does that help?
rScotty

Yes Understood.
So it was to dark to see the site glass in the barn. But I did pull the plug from bottom of transmission I guess it is. Oil was clean and clear . No milky.
So yes I am getting air from somewhere. As woody has said I must have over tightened one of 2 things. Can only be the filters. Was all snow under machine this morning didn't see any fluids .
on the snow

Fxfymn413 · Dec 9, 2021

When doing any trouble shooting do not overlook what occurred just before the trouble started and never start talking yourself into thinking it is the worse possible thing that could occur.

In this case you changed the oil and filters. Since nature abhors a vacuum air immediately went into the system to replace the oil you drained out and my bet is that some of it got into a high spot in the system, got emulsified into the oil, and has to work its way out.

Unless you have come up with a way to make water with the tractor while it sits there is no chance you got water into the system since you said you did not wash it or expose it to any other water source. Be patient and it will self cure.

And not to nag but using the spilled oil was probably not too wise. I get it since I'm as cheap er..thrifty as they come but 5 gallons of oil around $100.00; repairing a dirt contaminated hydraulic system; way more than that. And a trip to town to buy oil..a few hours; repair time..a few weeks.

Smokeydog · Dec 10, 2021

Saw on market place a converted water heater used to remove water from hydraulic oil for large excavator size equipment. A novel approach I didn’t know existed.

rasorbackq · Dec 14, 2021

Update:
let tractor sit due to weather for a couple days . Oil in site glass was new oil colour. and after 15 minutes of use it was milky cloudy again.
Still had no time to check filters

rScotty · Dec 14, 2021

rasorbackq said:
Update:
let tractor sit due to weather for a couple days . Oil in site glass was new oil colour. and after 15 minutes of use it was milky cloudy again.
Still had no time to check filters

I'd say that is a typical suction side air leak. Others may want to chime in too.

But it sounds to me that what you are seeing are micro-bubbles in the hydraulic oil. Downside is that as the hydraulic pump makes those bubbles it also bursts them and popping the bubbles creates micro-pitting on the hydraulic pump face - which will degrade the mirror finish on the pump gears and eventually ruin it.

So unless someone has another theory I'm going to say what you have is air getting into the hydraulic pump. It can be coming in by two pathways. The easiest to fix path is somewhere in the suction line somewhere between the sump and the pump - that includes the filter seals and especially the hose ends. Often a suction leak in that path will cause oil to slowly drip out when the engine is not running. That's how to find it. This is when you WANT to have a leak to fix. The problem is this is not 100% sure if you don't find a leak. That is because although all suction path air leaks do put air into the hydraulic fluid when running, not all of them leak oil when not running. But most do.

The other way air can come in is entering past the oil seal inside the hydrauic pump where the pump is being driven by the engine. You suspect that when you can't find a leak as above.

Neither one is all that difficult to fix, but has to be done.

good luck,
rScotty