Yesterday I noticed the hydraulic oil has a milky amber appearance. In the spring of this year I had changed the steering gear box along with the hydraulic oil and filters.
I thought it might be entrapped very small air bubbles, but leaving a small sample sit overnight did not change the appearance.
The engine oil and transmission dipsticks look fine.
How could water get in the hydraulic system?
Has anything been pressure washed?
No pressure washing.
This is a new occurrence correct, it was okay last month? Very strange. Guess you could get analyzed to help locate the source. Water would also separate setting over night somewhat.
After setting a few days if you have the chance, crack open the drain plug on the tank and see if you can drain some of the water out.
I had a '71 Mack truck with a Cummins 335 engine with a pin hole in one of the liners. Every morning before starting I would open the drain plug and let it drain until the oil showed up then screwed it back in. It was still that way years later when broken engine mounts put the fan through the radiator while low bedding my 977 Cat enough damage terminated the truck.
Is there a cooler for the hydraulic system? I need to go down and trace the hydraulic lines.
On my 99 there is a oil cooler for the hydraulics and it is oil to air. Maybe yours is oil to water.
Oil to air cooler between CAC and radiator. No possible leakage in to oil. Condensation? Drawing moisture in during cooling cycle after shutdown?
Possible, but have never seen/observed/experienced it.
If the seal on the cover of the hydraulic reservoir is bad then a hard wind driven rain could blow water into the reservoir. I worked on one several years ago that the oil was milky too. It had also had the steering box replaced previously. I thought that possibly a different type of oil was put in, still think water. I drained it, replaced the filters and filled it with new 15w-40 engine oil and removed the return line and ran until clear, then hooked up the return line and refilled. No further problems. I also replaced the rubber seal on the lid.
I just had the same thing on my coach. Took cover off and found there was no gasket on cover.