5 Ton Power Steering Question - Steel Soldiers::Military Vehicles Supersite

Jones · 06-07-2007, 00:44

OK Guys, here's a topic to debate.
Got a 5 ton power steering system and the L.O. for it calls for HDO 10w (10 weight motor oil); and a power steering pump that runs with power steering fluid. How close are 10w and ATF? I don't want to hurt the pump by running 10w through it and I don't want to hurt the power steering system by running ATF through it. So what do I do, Dear abby?

cranetruck · 06-07-2007, 03:39

I'm in a similar situation, got five gallons of ATF (Dexron) on the shelf now for the xm757, but am having second thoughts about replacing the Allison transmission fluid with it. The LO calls for 10W motor oil (OE 10) and that's what's in the transmission now from the looks of it.
I have mixed ATF and a fine oil (actually pneumatic tool oil) in a beaker and they mix perfectly, no separation. Not sure what that proves, but did it anywhow.
Read an article written by Steve Turchet where he used ATF in automatic transmissions instead of 10W oil and he reported no problems. Those were M211 trucks.

The power steering also calls for OE 10.

Bottom line is OE 10 and ATF must be very similar, so to repeat Leonards question, what's the difference and where does power steering fluid fit in?

Currently leaning heavily towards using OE 10 for both systems and returning the AFT....

(This is not to steal your thread, Leonard, just wanted to reinforce the problem)

rumplecat · 06-07-2007, 06:53

There is 90 weight gear lube in mine and it runs fine, I have the old style PS.
James G.

acetomatoco · 06-07-2007, 06:54

The power steering setup on 5 tons is designed for engine oil...why would you want to change.?.. Even the 800 series pump, a separate belt driven pump, is supplied with engine oil..

cranetruck · 06-07-2007, 08:04

Quote:

Originally Posted by acetomatoco

The power steering setup on 5 tons is designed for engine oil...why would you want to change.?.. ..

Ref Transmission fluid: For one thing, conflicting info from the manuals. The TM -10 calls for OE 10W, the LO calls for OE (could be 30, could be 10) and the Transmission TM calls for Transmission fluid type C2 (see attached). In addition the newer Allisons are using Dexron II.

I have found Texaco TO-4 type C4 10W "Drivetrain fluid" to confuse matters a bit more.

I haven't even started checking on the power steering yet.

Jones · 06-07-2007, 10:50

Rumplecat, would that 90w be in the early "Armstrong" type power steering?
Ace, I think Bjorn and I are concerned about wounding something we've worked hard on and something we'll eventually have to find parts for, and repair, out in the middle of nowhere should we make the wrong decision. Going with ATF is to keep the pump on my Cummins happy which is not a swap-out-and-use-a-different-kind item as it's part of the air compressor assembly. Compatibility with seals and hoses first comes to mind; as well as flash points for either as surprising amounts of heat are generated when running "non-compressable fluids" in hydraulic systems under load.

Jones · 06-07-2007, 12:30

OK... Just got off the phone to an outfit that does all kinds of heavy duty power steering work and got some info to share.
First; they say not to use 10w motor oil in power steering applications. Their recommendation is either Dexron with the warning that it's flammable and not safe around gas engine apps because of the chance of fires from leaks or burst hoses. The second recommendation is 15-40 motor oil as long as it's not synthetic. This is from an outfit that works on ex-military 2 1/2 and 5 ton trucks converted to fire-fighting rigs.
Got a tidbit of information in passing that's even more valuable. To all us builder/experimenters out there; Make sure everything in your hydraulic system is compatible. Turns out the power steering pump on my Cummins is way over-pressured for the Ross box and assist ram on the baby HEMTT. The tech guy says running the two systems together is a great way to assure them that I'd be back for relacement components time and time again, in between the numerous times I could be spending replacing steering stops and knuckles. For a handy tech tips .pdf file as well as other info go to www.babsteering.com and click on the services tab.

rumplecat · 06-07-2007, 13:05

Jones:
I am not sure I was told I have the original steering on my M543A2 wrecker, not the update version? So I should dump my 90 wt. and go with Dexron (ATF)?
James G.

cranetruck · 06-07-2007, 14:26

My jury is still out on this one.

There was a multi issue article on oils in the MVM a few years ago, I got some reading to do....

Jones · 06-07-2007, 19:07

Rumplecat,
Give the tech guys at BAB Steering a call and ask for Bill Carlson in tech support. He says he's been at this for 45 years and can give you the straight dope on what you want to run. Gotta say though that, to me, 90w sounds pretty stiff for power steering apps. More like what you'd use in a manual steering box.