Power steering hydraulic fluid

[Fred Cook]

I understand that the radiator fan, slide hydraulics and the power steering all run off the same hydraulic reservoir... correct?  Believe this reservoir is the one located in the back curbside basement compartment.  Anyway, is there any certain hydraulic fluid I should use or is it just plain red ATF?

[Gerald Farris]

Fred,
The hydraulic reservoir that you referred to is for the engine driven pump that powers the cooling fan and power steering only and it uses Dexron III or TranSynd fluid. You slide hydraulics are electrically powered by the same pump and system that operates your leveling jacks and it uses Dexron III fluid.


Gerald

 

[Jerry Emert]

Fred, I noticed the year of your coach.  I have the SMC leveling system (levels to axles) and the reservoir for the levelers and slides is just behind the battery compartment between the batteries and the big square reservoir for the power steering and cooling fan.  It is cylindrical in shape.  My power steering reservoir has Amsoil ATF in it.
Jerry

[Fred Cook]

Jerry, yep... same as mine. The power steering reservoir is easy to access but the leveling reservoir is hidden and hard to reach. I just needed a sanity check on what type of fluid goes in because it is a bit low. Thanks!

[Bill Sprague]

I was never able to establish what was used by Beaver/Monaco.  My best guess was ordinary hydraulic fluid.  When asked, the dealer tech said, if necessary, "just add transmission fluid".  As a closed system, it should never need any extra unless there is a leak somewhere.

Consider the cost of a pump/motor component failure, it may be wise to drain/flush/fill with synthetic Transynd or similar.

If the power steering/cooling fan system fails, the cost of a rebuild can make the market value of an older Beaver near zero.  Make sure it does not fail!

[Dave Atherton]

Gentleman, the subject of different hydraulic fluids within a closed loop hyd system. Bill is very correct, damage has and will happen by break down of hyd fluids. Internal wear with hyd pump, hyd valve and the hyd fan motor which will fail first. Most hyd pump use fluids that do not break down. Good example; Dexron fluids used in Allison transmission required fluid replacement every 25,000 miles. You can change over to Transyn hyd fluid that does not require fluid change other than filters for 100,000 miles.  Caterpillar has been marking hyd fluids that do not require change for 6000 hours.  Tellis Aw-45 another high hour hyd fluid used in air compressors. Hyd fluids will break down from heat and I would suggest with any side hyd driven radiator that you take oil sample after getting a base line set. Understand, I’m not running down different products but with hyd oils there is a big difference in usage that in that heat will break down and cause internal failure of components. Oil sampling will provide early warning of system break down. Dave Atherton Retired Cat Mechanic

[Fred Cook]

So, I should be able to replace and/or mix Dexron VI with Dexron III with no problems... right?

[David T. Richelderfer]

Fred - I am not an engineer nor a mechanic.  But somewhere along the line, I remember hearing that you can substitute newer formulations of DEXRON in place of older formulations, but not the reverse.  For example, if a manual specifies DEXRON IV, then you can use DEXRON IV, V, or VI; but not DEXRON I, II, or III.