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Questions: 1993 U280 Hydraulic System

June 04, 2014, 12:08:30 am

So, I got a wild hair this morning and decided to tackle the hydraulic filter change project.  My '93 U280 has 2 separate hydraulic tanks - a larger one on the driver side and a smaller one on the passenger side.  From my reading on the forum I have learned the big tank is part of the cooling fan circuit, and the small tank is for the power steering circuit.  Each circuit has its own dedicated pump.  Neither tank has any stickers or decals indicating the correct fluid to be used.  I'm pretty sure the cooling fan system uses motor oil same as the engine.  I'm not clear about what fluid is used in the power steering system.

First question: Are these two systems tied together, or do they operate independently?  Since each system has a pump, and a tank with dip stick to check level, that would make it seem like they are completely separate.  If they are indeed tied together somewhere, then I would assume they both use motor oil.

The small tank has a wing nut on top that holds the cover on.  Took cover off, pumped about 1 gallon of fluid out of tank as per forum suggested procedure, removed spring and extracted the single filter.  It is 5" in diameter, and 4" tall.  I cannot find a part number for this filter anywhere in the owner's manual.  I did find a single reference in a very old forum post to a part number LF637.  Can anyone verify that this is the correct filter number?

The big tank has the 2-piece clamp holding the lid on.  Removed clamp, removed lid, pumped about 2 gallons of fluid out of tank, removed spring and extracted the SINGLE filter.  This caught me off guard - I was expecting 2 or more filters.  I assume this filter is a 84101B, but would like someone to verify that.  The old filter is 4" in diameter, and 5" tall.  Could someone measure one of their spare 84101B filters to see if these dimensions match?

The "fluid" I removed from both tanks looks pretty much the same color.  The stuff from the power steering tank might be a little bit thinner, and smells slightly different.  I can't really tell if they are both motor oil, or if one is power steering fluid.  Any suggestions for a way to tell absolutely for sure?

The rubber gasket #999-55A on the big tank lid was not in bad shape, but I will buy a new one just to be safe.  The small tank lid has a flat rubber gasket glued to the underside of lid.  It looks fine and will be reused.  Both tanks are in excellent condition, with very little rust or corrosion.  Photos below of both tanks.  (Ignore the red tube sticking out of the big tank in one photo - it is part of my "pump-out" device)

Thank you for any guidance on filter numbers and what is correct fluid to use in both systems.

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Re: Questions: 1993 U280 Hydraulic System

Reply #1 – June 04, 2014, 10:36:22 am

 Chuck, looking at your pictures I would say that if the single filter was being held down correctly over the centre stud then it does only use 1 filter. Mine is a much bigger single tank and has multiple filters so yours being 2 smaller may be that is why only 1. I would say looking at the drop of oil at bottom that both use 15-40 Delo 400. The name on mine is Nelson so would think yours are same. Check Beamalarm for them then google specs to check size. Hope this helps
JohnH

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Re: Questions: 1993 U280 Hydraulic System

Reply #2 – June 04, 2014, 03:59:30 pm

@Chuck Both of my systems use 15-40W Delo 400 for the hydraulic fluid. The two systems are independent. One tank (little one) for power steering and one (big one) for to power the fan motor(s). I have 3 of the 84101B's in my fan reservoir and when I checked my power steering reservoir no filter found! Not sure it was spec'd that way or someone pulled it along the way.

see ya
ken

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Re: Questions: 1993 U280 Hydraulic System

Reply #3 – June 04, 2014, 09:07:39 pm

I have another question.  My coach came with a excellent package of factory manuals and paperwork (thanx to the prior owners).  I have looked through every book, and have not located a schematic of the hydraulic system.  Was this normally included in the original set of owner's manuals?  If not, where would I find one?  If I call FOT, would they be likely to have the hydraulic system schematic on file for my coach?  I've never requested anything from FOT, so I'm not sure what they can or cannot supply.

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Re: Questions: 1993 U280 Hydraulic System

Reply #4 – June 05, 2014, 09:56:43 am

@Chuck they probably do have a diagram. They had one for mine. Call tech support at FOT.

The one I saw didn't make much sense to me at the time. It was easier to make my own drawing after I traced out the reservoir, pump, cartridge valves, and fan(s). I just traced out where each hose started and ended.

Here is the one I did. It won't be much help to you since my system uses a tandem pump and one fan motor.

see ya
ken

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Re: Questions: 1993 U280 Hydraulic System

Reply #5 – June 05, 2014, 07:47:05 pm

Ken (John H also),

Thanks for the helpful replies.  Ken, especially, I consider the "Hydraulic Guy", since he has probably R & R'd his hydraulic components more than anyone else in recent memory.  Even though his system is different than mine, I still get a lot of value from his comments.

I have become convinced that the "fluid" in both my hydraulic systems is indeed motor oil.  After the old stuff I removed settled out in the milk jugs, it was definitely a golden brown color and coated the inside of the container like oil.  I also found 2 or 3 references in my owner's manuals to using 15W40 oil in the power steering system.  The Sheppard Power Steering service manual also lists motor oil as a approved fluid.  So, motor oil it is!

I have done extensive research online and I think I have answered my own questions about the filter part numbers.  By comparing the physical dimensions of the filters I removed to the tech data at numerous filter sales sites, I have come to the following conclusions:

1.  The filter I removed from the big tank (cooling fan system) matches the stated dimensions of the Nelson 84101B, so I assume it is either a 84101B or a clone.  Going by the condition of the clamping ring and rubber gasket on that tank, it is possible that this filter is original and has never been changed.  I have found 3 possible crossover numbers for this filter: Fleetguard HF6238, Baldwin PT8487, and Donaldson P550698.

2.  The filter I removed from the small tank (power steering system) is (I believe) either a Fleetguard LF637, a Baldwin P528, or a Donaldson P550637.  All 3 supposedly match the physical size of the old filter, and as I said earlier I found a old post (by Gary Bouland) referring to a number LF637 filter being used in the power steering tank on his coach.

I went to the local Cummins shop today and asked about the Fleetguard filters and the rubber gasket (Fleetguard 99955A-20).  They didn't stock any of them, and said they didn't even list the gasket as available from any of their warehouses, even though it says on their website that this part is available for sale.  As I left I noticed a sign on the service counter listing "Shop Hour Standard Pricing".  Under "RV Service" it said "$160 per hour - 2 hour minimum".  OUCH!!  Don't think I'll be going there, unless it's a emergency.

I then went to B-Line Filter & Supply in Odessa.  They had both of the Baldwin filter crossover numbers in stock, so I got one of each.  I asked about the rubber gasket, and they came up with a Baldwin G309-B gasket.  It looks pretty close to me - the overall diameter is perfect, and the diameter of the rubber (cross section) is about right.  The only thing I'm wondering about is the "shape" of the rubber cross section.  I crossed the Baldwin number over to a Donaldson number - here is a link to a picture of the Donaldson gasket.  This is exactly what the Baldwin gasket looks like - notice the "parallelogram" cross section:

http://www.filterspro.com/detail.cfm?part=1699489

I can't tell what the old gasket looked like originally.  If anyone has changed this gasket recently, and remembers what the new one looked like, I would really appreciate a opinion on whether this is the correct piece.  Ryder Fleet Products lists the Fleetguard 99955A gasket for sale.  I may just order one so I can compare it to this one...

Thanks again for any help!

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