Power Steering Pump!

[muddog16]

For some reason Detroit Diesel saw fit to incorporate their power steering pumps into the drive systems on the rear of the engine. A few months ago Sean mentioned that his engine oil levels started to increase and the culprit ended up being the seal on the power steering pump on his 8V92.  My question is this: Is anyone aware of a power steering pump capable of handling a system on a bus that is external and belt driven like our everyday normal vehicles?  You would think as expensive as it is to rebuild these beasts why would you take the chance of a $20 seal destroying your engine?  When just about every car/truck that I am aware of uses a belt driven pump!  It can't be a saftey issue!    Input as always is appreciated!

[Stan]

Apparently the problem with leaking seals on power steering pumps has been so small that the manufacturers and users favored the gear driven pump for it's dependability. 

If you want to experiment with different power steering fluids and different engine oils than what the system was designed for, you are on your own. The bulletin boards are full of threads on "What additive to use" and "what kind of oil I use", and lots of sad stories on engine failures. Very few people will go to the expense to determine why a component failed when they are facing the cost of an engine rebuild.

[skipn]

Muddog16,

      Power steering pump on most auto's are vane pumps. The bigger rigs tend to use a gear pump. As long as the
pump can handle the PSI and volume requirements then yes there are a lot of belt driven pumps. These pumps
are basically nothing more than a hydraulic pump. you can order the pump and correct sized pulley from a lot of
places. I personally would favor a single flat belt versus 2bl v belt set up to handle the higher friction needs
for non slippage.

   Hope that helps
Skip

[TomC]

Virtually ALL medium and large engine currently being used in trucks and buses have gear driven power steering pumps.  Personally- I like the fact that my engine has NO belts at all.  Course that means that if anything fails, it might take the gear drive with it.  I did have an alternator freeze up on my Mercedes recently.  It just burned out the belts, but still had to get it towed since it also powered the water pump (as is especially the case now with serpentine belts-one belt powering everything).  I have owned four cars, four big trucks and the bus-never has anything ever happened to the power steering pump.  I think Sean's was a fluke, and should not be used as rule.  Good Luck, TomC

[Tom Y]

Muddog, Maybe find a power steering fluid that is compatible with engine oil?  Tom Y

[makemineatwostroke]

Pat some power steering pumps have a leak detection hole at the bottom to show when a problem is developing and the gear drive is not only common to DD, Cat and Cummins also have it.In reading Seans post you will see the fiber drive broke saving him a gear train failure also most power steering pumps can use engine oil it's just a problem on cold days.I don't think you would be happy with a belt drive on the power steering, the best part of owning a bus is you can do it your way but the problem for you would be finding a belt driven pump compatible with your steering and the valves that would match the existing system

[HB of CJ]

Funny you should ask.  My ex-Crown had an updated TRW (Ross) power assist steering gear box retrofitted at sometime in the coach's past.  The twin belt driven Victor's VT42 (RH) appeared to be laboring to properly run the power assist steering.  The new owner is aware of this.  The fix would appear to be a larger pump that could also drive any future leveling devices for a Bus Conversion.

I for one would also prefer a gear driven power steering pump, thus freeing up the twin drive pulleys for a possible future dashboard AC unit like boggiethecat did on his Crown.  The potential problem has already been addressed--a seal failure can ruin an expensive Detroit Diesel.  The question is how often does this happen and is a gear driven pump inherently a better idea.  May be.

However, my old Crown Super Coach ex-schoolie was designed sossss if the power steering ASSIST pump failed, one could simply cut the two drive belts and still safely drive the bus, like I did coming up North from Southern California to SW Oregon.  If a gear driven pump fails, then I do not know what would happen--perhaps the Bus Converson would be dead in the water until repaired.  Good luck. 

[Sean]

Since perhaps I ultimately started this discussion, a couple of comments:

First off, since you now know what to look for in the event your power steering craps out, the risk of engine damage is low.  My steering system has an unusually large reservoir, meaning that perhaps some two gallons of ATF could end up in the crankcase before I'd know about it.  Most systems hold less than that, so maybe a gallon or so.  That's in 7-8 gallons of oil -- probably not enough dilution to cause any engine damage in the amount of time it would take you to notice the problem and have it corrected.

I had two additional issues that contributed to premature bearing wear:  first, I did not even know this condition could exist, and so I continued to put ATF in the steering reservoir, to the tune of another several gallons.  Second, we were racing to respond to a disaster with the Red Cross, and we made the decision to press on rather than stop where we were to effect repairs.  Even so, the bearings did not suffer all that much -- I replaced them as a precaution, but I've since been advised that it was probably wholly unnecessary.  Bearings, after all, are made to wear.

Secondly, most power steering systems in these coaches will run fine on 15W-40, although they may be a bit whinny at low temperatures.  My weird German-built (Mercedes) steering box is particularly noisy, and so we went back to ATF after the pump was replaced.  If I had an MCI or GMC, I'd be inclined to just run the 15W-40.  That would pretty much guarantee that a seal failure on the pump would not do any engine damage.

Lastly, of much greater concern than the ATF leaking into the crankcase was that the fiber drive disk disintegrated.  (I believe that this was the root cause of the seal failure -- once the disk was gone, the drive dogs slapped together steel-on-steel, vibrating the seal to an early death).  My advice here is to remove the steering pump and inspect this disk as well as the seals any time you have easy access to it, such as during in- or out-of-frame overhaul.

FWIW.

-Sean
http://ourodyssey.blogspot.com

[muddog16]

Wow!  Great response thanks!  Sometimes I feel like an old woman worrring about stuff that I have no business thinking about!   I'm sure I will leave the original pump in there now I think I'll rebuild it while its out new seals should do it!  Oh yeah, Steve there are new photo's at the site, with this weather kicking butt.........I'm moving right along.....I love Spring!