Question about hydraulic filter change

[Z-Michigan]

It's time to change the hydraulic filter on my JD 5105 utility tractor. The filter and its replacement is a big spin-on the size of a coffee can, and is mounted to the left and below the seat. The instructions seem to indicate only hand tightening the new one, but I can't get the old one off by hand, and my current filter wrench isn't big enough (I will be buying a bigger strap wrench ASAP). Is this level of tighness typical? The tractor has just over 100 hours. How tight should the new one be put on?

Related question: while the replacement filter is basically a spin-on can filter, it appears that the gasket is NOT permanently attached to the filter (the way that an oil filter gasket normally is) and instead the package with the filter has what appears to be a giant O-ring the size that would fit just inside the filter rim. Am I correct in thinking that this is a gasket that I need to put just inside the filter rim before installing the filter? Is it that simple or are there any tricks to it? Do I need to smear hydraulic fluid all around this O-ring, like I would do on the fixed gasket of an oil filter?

 

[638]

Install the new filter hand tight only (as tight as you can get it by hand). The gasket will stick to the mounting surface and make it harder to remove. I would use a dab of grease to hold the new oring in place. Yes, lube the new oring.

ron

 

[john_bud]

If there is any residual pressure in the system, it will make the filter a real bear to get off.

Try it when the tractor is as hot as you can get it. Drop the loader, lower the 3pt all the way down and leave the loader control in "float". There shouldn't be any residual pressure, but...

jb

 

[jinman]

At 100 hours, this is probably your first filter change. At the factory, it seems they hire a gorilla to put on filters and it's always tough to get them off the first time. Just keep looking until you find something big enough to do it. If you have to use the "big screwdriver driven through the filter" method, you won't be the first one to use that method.

Also, the o-ring may be separate because the mating surface on the tractor has a land for the o-ring. When you get the old filter off, just look to see how its o-ring is mounted. That will give you the best reference. I would certainly grease or oil the o-ring.

I think you will find that the hydraulic filter is on the suction side of the hydraulic pump as it draws fluid up out of the reservoir. The filter probably needs to be tight enough to not leak air, but I doubt it is under prositive pressure. Hand tight should be tight enough.

 

[Z-Michigan]

Thanks all. Yes, I should have mentioned this is the first filter change. I'm glad to hear that this is on the suction side; I was wondering how a conventional filter would hold up to 2500psi hydraulic pressure, but I don't know much about hydraulic systems.

I didn't think about using grease on the O-ring (I was planning to use hydraulic oil) or the possibility of a land for it, that is very useful info.

Jim, a gorilla put my oil filter on too, but at least the strap wrench I have fit on that one! And I put the new one on only hand tight, which is still pretty tight.

 

[Farmerford]

Z-Michigan:

Many hydraulic filters are in the return line; that is, the low pressure line that transmits "exhaust" fluid from the directional control valves on the three point hitch and front end loader back to the tank rather than either the high pressure line carrying the pump output or the suction line carrying fluid from the tank/sump to the pump. Filters are usually not in the high pressure line for the reason you mentioned: a very heavy case is required to withstand the pressure. Filters are not in the suction line because the pressure drop across the filter can cause damaging cavitation at the pump.

For example, I have a Prince PTO pump and Prince recommends no more that 3psi of suction at the pump inlet to avoid cavitation. Therefore, any filter on the suction line would either have to be very large to allow sufficient flow to the pump to keep suction below 3psi or it would have to have a bypass valve that would permit flow around the filter at 3psi.

The filter on my system is on the return line from the hydraulic motor which is driven by the pump. When the fluid is cold, the pressure drop across the filter is 10-15psi. Therefore, if that filter were moved to the suction line, it would create an unacceptable amout of suction when the fluid was cold. Even when the fluid is hot (160 deg F), the pressure drop across the filter is around 5psi.

Therefore, in my system the filter has to be in the return line. The suction line does have a 100 micron mesh screen inside the tank at the suction port that would catch large particles, and the screen has a 3psi suction bypass just in case the screen gets stopped up. But a typical 10 micron (absolute) filter has too much resistance to flow (and therefore too much pressure drop across it) to put in the suction line.

 

[jinman]

Z-Michigan:

Many hydraulic filters are in the return line; that is, the low pressure line that transmits "exhaust" fluid from the directional control valves on the three point hitch and front end loader back to the tank rather than either the high pressure line carrying the pump output or the suction line carrying fluid from the tank/sump to the pump.

I agree that on some systems the hydraulic filter may be in the return line, but I think you will find many of our CUTs put a filter into the suction line. That is exactly the case for my New Holland. Both the suction line oil to the 9.8 gpm main hydraulic pump and the input to the HST charge pump are pulled through a filter on the suction side. I suspect your PTO pump's flow is much greater than the combined flow of both the main pump and HST pump on my tractor.

A filter in the return side of the hydraulic system MUST have a bypass valve to keep it from exploding if the filter or line becomes clogged. The return line can rise to full system pressure if there is no bypass valve. A filter on the suction side requires no bypass since the pump will begin to cavitate and the reduced performance of the system will be a red flag that maintenance is required.

 

[joewilshire]

On my "home made" log splitter, I put a 10 micron filter with a bypass built into the filter holder, on the return line leading back to the reservoir.

However, the filter expanded to the point of causing a seperation between its base and side allowing quite a bit of fluid to leak. I guess I'm lucky that this happened instead of the hose rupturing and spraying me with hot, pressurized fluid.

This happened twice. (expansion of filter).

I thought that the bypass was supposed to keep the filter from doing this.

I am going to try and do what Jim has setup and put the filter on the suction side of the pump.

My question is this... Should I get a different base that does not have a bypass? And do you think a 10 micron filter would make the fluid cavitate to the point it would harm the pump, or should I use a 100 micron?

Any suggestions would be of great help to me.

Thanks.

Joe

 

[Wayne County Hose]

On my "home made" log splitter, I put a 10 micron filter with a bypass built into the filter holder, on the return line leading back to the reservoir.

However, the filter expanded to the point of causing a seperation between its base and side allowing quite a bit of fluid to leak. I guess I'm lucky that this happened instead of the hose rupturing and spraying me with hot, pressurized fluid.

This happened twice. (expansion of filter).

Are you sure that the filter block is mounted for the proper direction of flow? It's possible it is installed backwards.

I thought that the bypass was supposed to keep the filter from doing this.

I am going to try and do what Jim has setup and put the filter on the suction side of the pump.

My question is this... Should I get a different base that does not have a bypass? And do you think a 10 micron filter would make the fluid cavitate to the point it would harm the pump, or should I use a 100 micron?

Any suggestions would be of great help to me.

Thanks.

Joe

Joe, I think you need to fix the problem that is causing your filters to rupture. Any log splitter I have seen has the filter on the return side.

 

[joewilshire]

Yep. The filter base has arrows that show which way the flow shoud be. I did install it correctly.

Joe.