50 hour service

[SkyPup]

</font><font color="blueclass=small">( Ive just completed my 50 hour service with everything but changing the hydraulic fluid. I was wondering since the hydraulc fluid does not wear out like the engine oil how important is it to change it at this early interval )</font>


The specific reason that you need to change the oil out is that hydraulic filters are different from crankcase diesel engine oil filters and diesel engine fuel pump filters, the hydraulic fluid operates under completely separate conditions.

Hydraulic filters have to provide allot more flow (gallons per minute) than either a diesel crankcase oil filter or a diesel fuel pump filter, without creating excessive backpressure.

This requires that the capacity and filtration orifices in hydraulic filters be much larger than either diesel engine oil filters or diesel fuel pump filters. Typically engine oil filters provide 8-10 micron filtration at the best, while diesel fuel pump filters provide about the same, however hydraulic oil filters are nomially about 80 microns or so for filtration orifice size.

The primary size of the destructive abrasive steel particles in modern diesel engine motor oils are < 5 microns, same in diesel fuels, and same in hydraulic fluids. So your hydraulic filter at best only removes the largest chunks out of the oil flow to keep them from ruining the hydraulic pump, which is a sensitive close tolerance device, similar to your engine and fuel pump.

Quite often, the best way to remove the <5 microns abrasive particles from the oil that escape the filtration devices (<80 mocrons in hydraulic filters) is to use a magnet to capture the steel residue, although all of the residue is not always ferrous.

Change the hydraulic oil now @50 hrs like your manual states instead of changing the hydraulic pumps and being sorry later.....

 

[BrettW]

Just to add a dumb question if I may, Is it possible to tell if the oil is "dirty" by just looking at it? Will it look cloudy, dark, thick? thanks, bw

 

[gsxr1100]

no, unless you are super man and can use your eyes for the spectro oil analysis.

Unless the fluid is pure white from water, you can't tell anything just by looking at it.

then again fluid color means zero most times.

 

[SnowRidge]

<font color="blue"> (This requires that the capacity and filtration orifices in hydraulic filters be much larger than either diesel engine oil filters or diesel fuel pump filters. Typically engine oil filters provide 8-10 micron filtration at the best, while diesel fuel pump filters provide about the same, however hydraulic oil filters are nomially about 80 microns or so for filtration orifice size.) </font>

Are you sure about the 80 micron figure?

As an example, one of the hydraulic filters I use is a Wix 51551, which is a 10 micron filter. Wix lists a whole slew of applications for it, and not all applications are listed, I'm sure.

I think the most important reason for the 50 hour change is the lack of a bypass valve. Automotive oil filters have a bypass valve, which makes sure the engine gets oil even if the filter gets clogged. Hydraulic filters don't seem to have these, so they have to be changed before there is any chance the filter can clog, otherwise the hydraulics will be starved and severely damaged or destroyed.

50 hours seems to be a safety factor and an industry convention.

 

[SkyPup]

All the OEM hydraulic filters on all my Kubota's are 80 micron.


Are you certain that your tractor's hydraulics are capable of sucking 10+ gallons per minute of hydraulic fluid through a 10 micron filter at ambient temperatures all year 'round????

I don't think so.....

 

[slowrev]

My tractor has a high side hydraulic filter that goes down to 20 microns. Yes it also has a 100 micron screen on the suction side. the 20 micron filter is between the pump and the rear lift box/remotes.
Ben

 

[SnowRidge]

<font color="blue"> (Are you certain that your tractor's hydraulics are capable of sucking 10+ gallons per minute of hydraulic fluid through a 10 micron filter at ambient temperatures all year 'round????)

I don't think so..... </font>

10 micron is not only specified, it is a warranty requirement. How do you know what the flow rate is? I did not specify any particular brand or model.

There well may be 80 micron hydraulic filters, and there certainly are 10 micron hydraulic filters. The Wix 51551 is one such.

I just checked my other tractor. It uses 35 micron filters.

 

[SkyPup]

I have a 10 micron hydraulic filter on my Barnes hydraulic pump for my log splitter's ram. But all our Kubota and Massey tractor hydraulic filters are 80 micron.

I don't know what the flow rates on your tractors are, but I do on all of ours.

Have you thought about going to a 1 micron filter at your 50 hour serivice to better protect the 0.5 micron clearances in the hydraulic pump?

 

[SnowRidge]

I'm done with this thread.

 

[BobCorazza]

Replace the fluid, filters, and clean the intake screen if it has one. My Kubota has nominally rated 60mic filters (if memory serves) when I looked into the specs. I added a 10mic return filter that is capable of 10gpm. I also made up an offline filter that I run once in awhile to filter down to less than 1mic. An advantage of the offline filter is that is removes water / moisture.
Being a "filter nut" I also filter the engine oil and diesel down to <1mic.