Hydraulic Fluid Maintenance (Fan/Steering)

[Mike Groves]

Does anyone have the maintenance period for hydraulic fluid/filter for the Hydraulic fan/steering on a '99 through '01 SMC era Marquis?  Also, what is the fluid capacity?

Thanks,
Mike

[Bill Sprague]

When I tried to find that answer I got wide ranging opinions.  On one end it was that hydraulic fluid does not wear out and that changing the filter occasionally would keep out the chunks.  On the other end was that it should be drained and replaced with Transynd for longer life.   Of the Beaver failures I'm aware of (during a decade of paying attention), none seemed to be related to fluid failure.   There have been some mounting brackets and fan blade failures.  Jerry Carr had the most traumatic failure with the pump coming apart and contaminating the entire system.  But, I don't recall anyone suggesting it was caused by old fluid.

Ours went 123,000 miles on the same fluid and three filter changes.   

[Dave Atherton]

Mike I have to disagree with your thoughts on (hydraulic fluid does break down.) This is
why a person has sticky hydraulic valve problems and hydraulic pump failure the hydraulic
Oil may look clean to some but point lost,heat will break down the special additives that
keep o-ring and seals from harding etc. good example dextron type 2 that used in transmissions
breaks down at 25,000 miles. If you are looking for something long life so you do not have
change, Cat makes a hyd oil that is rated for 6,000 hours and using oil sampling it does not break
down the if you change filter at 500 to 1000 hours.
Dave Atherton Retired Cat mechanic

[Fred Brooks]

        Hi Mike,

     Page 34 and 35 in the chassis manual state to change the fluid and filter every 15,000 miles or 18 months on a magnum chassis with Dextron 2 fluid which is also what Dave is saying, Regards Fred

[Edward Buker]

Like Bill, I have not changed this fluid in my last two motorhomes, but I did change the filter several times on my first motorhome over a 10 year period. After 5 years of ownership of the current RV I do have the fluid change on my list for this winter. The fluid by color, feel, smell seem to be good but I feel in the scheme of things maybe once in 5 years to do a fluid and filter change would be reasonable prevention and cannot hurt. You could possibly have it analyzed to make the call. This 5 year interval is just opinion derived based on "I ought to change it sometime". I have not heard of any fluid analysis results.

As far as the tank capacity, measure the length, the width, and the height to the fill level of the tank in inches (usually a sight glass). Multiply LXWXH together to get cubic inches. Multiply the cubic inches by .004329 to get gallons.

I just read the 18 months, 15K miles in Fred's post regarding the manual as well as Dave's post. That seems conservative to me. I do not think this fluid gets hot enough to cause it to break down like in a transmission. I have not IR gunned the tank after running, anyone know how hot this fluid runs, that would provide some insight.

Later Ed

[Bill Sprague]

        Hi Mike,

     Page 34 and 35 in the chassis manual state to change the fluid and filter every 15,000 miles or 18 months on a magnum chassis with Dextron 2 fluid which is also what Dave is saying, Regards Fred

Wow!  It will last a lot longer than than in a transmission where it has to do some "real" work!

[Fred Brooks]

     Hi Ed,

    If it's any consolation, it is on my list of things to do. I've been chipping away on all the maintenence on my coach because there were no records. Fortunately my coach appears to be loved because everything worked when I bought it and she is still pretty outside. Fred

[Edward Buker]

Fred,

You will probably remember doing some of these. I had an 89 Contessa on a Gillig chassis with the round tank that had a band on it and you removed the top of the tank to access the filter. You plunged your hands into the fluid to pull out a cloth pleated filter. The fluid was bright pink and the cloth filter was clean and looked new, but I changed that filter a few times anyway. I sold that coach in 2009 and it was 20 years old and that fluid had never been changed and still looked like what you would pour out of a new Dexron container. That may be extreme but that coach had about 90K miles on it and many years of that hydraulic fluid use. I am guessing that this 15K miles has no science around it and was a convenient interval of change, had to put something in the manual scenario.

If someone has an IR gun and Has been running maybe they would shoot the tank right after shutting down and report back. Dexron has some miles vs temp transmission recommendations which would give some insight.

Later Ed

[Fred Brooks]

         Thanks Ed,

    Thanks for the trip down memory lane, I agree with the responses but please don't shoot the messenger. I was just trying to answer Mile's question. I wonder if it is ok to use Transynd? and just be done with it. BTW Mike the capacity according to appendix C on page iv is 20 quarts with the filter change. Regards Fred

[Edward Buker]

Fred,

No intent to shoot the messenger :-) You have been spot on with your answers to the forum and have great knowledge regarding repairs and a variety of experience to call on that most of us do not have. It is best to just follow the recommended interval until something better is derived.

If we knew the temp we may have a better idea if this interval is even remotely rational. In my auto transmissions in various vehicles over time, I have seen color degrade and in this hydraulic fluid use I have seen none of that, so it leaves me curious as to what is the issues with this fluid and a longer change interval. My 20 years is a stretch but 18 months is hardly the gestation period as I see it :-)

I think a lot of the newer maintenance schedules derived by car companies are using science to keep the maintenance cost down as a selling perk. In general the miles and periods are getting longer as the fluids get better. This hydraulic fluid is an unknown as to how long in reality it will actually last.

As far as Transynd, Gerald was telling me that he planned on using it when he did this fluid change. I like the idea but I do not know if all the components in that system are OK with that change....probably.

Later Ed

[Mike Groves]

BTW Mike the capacity according to appendix C on page iv is 20 quarts with the filter change. Regards Fred

Fred,

Thanks.  Wow 5 gallons!  Ok, I guess I'll just wait for the dust to settle on this thread before deciding to do this now.  The last time I did it was in September 2013.  There was no drain that I know of, as the shop pumped the fluid out of the reservoir.  And I did have a new filter put on.  Since then, I've been no more than 15,000 miles in it.  I did read about the transynd when Gerald posted that idea.  I believe he said he was going to do it "next time", so I am not sure its been done yet and how its all working out. 

I am using the transynd in the transmission, and synthetic gear oil in my rear differential (which the shop said would last forever).  I've only kept the front oiled bearings topped up (should I be doing more?).

I am skipping the oil change this year based on the 25,000 mile concept posted previously.  I had the antifreeze changed out to a popular ELC knockoff less than 2 years ago.  My overflow tank is located in a different spot (not directly above the engine as is the case in 2000/2001 years) and I've not noticed any cracking in it.  There is also an engine fan on the back door which cuts down on the heat buildup in the engine compartment (runs all the time and 1/2 hr after shutdown), and a bigger engine box under the bed vs the slide out configuration I believe. 

A concern is I've not plugged the coolant filter loop since going with ELC, but have had it looked at every year during maintenance by the shop.  I am also running the ELC in the generator which only has about 700hrs on it.  Like you Fred, I seem to have gotten a pretty good coach.  Woodwork is almost all clear with some hazy places up front above the driver an passenger.  I do have the "window snakes" but so far no window fogging.

Mike

[Bill Borden]

Hi all,

Under the 'For what it's worth' heading, I switched over to Transynd about 3 years ago.  I felt it was time to service the hydraulic Fan/Steering system, as far as I could tell it had never been serviced.  So after reading up on the benefits of synthetic hydraulic fluid over the Dexron such as longer life, cooler running temp and improved protection for the seals, along with my research in the Forum and Gerald suggestions. I made the change.

After changing fluid in the tank along with the filter, I ran the system with the return disconnected and waited for the fluid color to change, so it would purge the pumps and the lines.

After the change over, the power steering seemed a little smoother and maybe a bit quieter.  But that is just my take on it, no real fact.

When we purchase our Coach it did not have any maintenance/service records, so I thought it was best to start going thru the Coach changing and servicing all the systems.  This was definitely on the list to do.

By catching up on the service will hopefully keep us trouble free down the road. 

Well maybe that's asking too much.

[Mike Groves]

Bill,

Is there a drain plug on your tank someplace?

Thanks
Mike

[Bill Borden]

Hi Mike,

It in a way it does, my coach has an unused port in the back of the tank at the bottom, if memory serves I used that port along with removing the filter.  The Return line is non pressurized with a hose clamp so it should be easy to spot, I used this line to return into an empty jug waiting for the fluid color to change.

Hope this helps,

Bill

[Fred Brooks]

        Hey Guys,

     Thanks for all the input, I think Bill helped me make up my mind on the Transynd and if Gerald endorses the idea I'm all in. BTW Bill, I am a firm believer that "An ounce of prevention is worth a pound of cure"
       Regards, Fred