Foam in hydraulic fluid.
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Dave M7040
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Typically cause of foamy oil is a leak on the suction side of the hydraulic pump letting air enter the pump.
Look for a piece of rubber hose on the suction line. Often used to join two pipes together. It will leak air in but you wont see fluid leaking out.
Dave M7040
the old grind
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Is 80-90 called out for hydro fluid? Many machines that don't spec ISO 46 hydro spec 15w40 diesel engine oil. I can imagine something too heavy cavitating when cold.
Roadworthy
Elite Member
80W-90 is pretty common in cars for transmission fluid for a stick shift or for a rear differential. I think you should check the manual to determine the proper transmission - hydraulic fluid for your tractor. They frequently use a general purpose fluid for systems with a shared reservoir.
Texasmark
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Hydraulic fluid is in the range of 15-20 Wt for pumpability reasons. Additives allow it to have a high pressure retention capability. On tractors using 85 to 140 mineral oil in the differential, they have a separate compartment for the tranny which can use it and one for the hydraulics which use HYDRAULIC FLUID, OR TRANS-HYDRAULIC-DIFFERENTIAL FLUID (THD oil), all being in the viscosity range I stated if you have a newer tractor with a common sump feeding all 3 functions. You mentioned that your hydraulics don't want to work and produce foam....... put the proper oil in the hydraulics and life will get better for you!
Topzide
Gold Member
In the O/M for my 1502 and 1704, it calls for a high quality low viscosity gear - hydraulic oil such as Bolens 1738157 or equivalent. I've been using an ISO-46 oil for 10+ years with no problems! 80-90 is a gear oil for front axle on 4wd not the hydraulic system of a small tractor!
the old grind
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I was thinking ISO 68 might be ok but not sure. What I am sure of is that I'd want to warm up the hydro a lot esp in cold weather. When 'plowing' snow this Winter at 15 F it dawned on me to cover the hydro oil cooler. I like to see snow melting on the loader cyls to be sure my juice is warmed up enough.
Even 80w will flow like half & half when it's up to temp. 15w-40 will flow like milk at 180 F. This one is curious, and I wonder if a filter substitution could inhibit cold flow, esp if 80w is called out by the maker. I'd be particular about that item & it's specs. WIMI I wonder what micron a 'factory' would be rated at.
Even 80w will flow like half & half when it's up to temp. 15w-40 will flow like milk at 180 F. This one is curious, and I wonder if a filter substitution could inhibit cold flow, esp if 80w is called out by the maker. I'd be particular about that item & it's specs. WIMI I wonder what micron a 'factory' would be rated at.
Topzide
Gold Member
That's the reference for a current oil. Same as Mobil 423 oil. And yes that's been discontinued also. Your local NAPA or Tractor Supply can get you what you need. At Tractor Supply you can use Travellers Premium Tractor Hydraulic fluid and be fine. Have used that in mine and have over a 1000 hrs on 1 and 500 hrs on other with that oil.