Power steering working intermittently

[Albert Balika]

I have a 2007 Contessa 42ft C-9 Cat. While driving through turns, tight or gradual, the power steering shuts down and I have to muscle the coach through turns either right or left. When I reach a straight away I get intermittent  power steering back, albeit it is not great. I changed the hydraulic filter about 1200 miles ago and all worked great. The specs call for Rando 46 hydraulic fluid. I used O'Reilly's virgin hydraulic oil 46 to top off and as I said all has been working well. I don't see any leaks at or around the hydraulic pump. The hydraulic fluid was down approximately 1.5 quarts. I topped the fluid off and at a standstill, the steering is very difficult, almost impossible. Any thoughts would be welcomed.

[Steve Huber Co-Admin]

Albert.
Do you have your exhaust brake switch on? This will cause the power steering to act up intermittently.
Steve

[David T. Richelderfer]

I found this by doing a GOOGLE search.  The question I asked is, "What if Rando 46 hydraulic fluid and Dexron 3 are mixed in a power steering application?"  Note: It is not clear to me if you had steering problems BEFORE adding the Rando to the power steering system.  Our coach calls for Dexron 3 or higher.  The following is the reply from GOOGLE:

"Can you mix power steering fluid and Dexron 3?

"Most people are wary that mixing the two fluids may damage the components of the power steering. If the two fluids have the same properties, then mixing them may not cause any problem. ... Some use ATF transmission fluid such as Dexron, Mercon, Type F, ATF+4, etc.)"


Also, I have read here on the Forum that power steering sometimes does not work well when the engine is operating at idle speed probably due to inadequate pressure from the power steering pump.

[Eric Maclean]

Albert
The symptoms you have described are indicative of low power steering fluid or air built up in the power steering system this should not be ignored as this can create a dangerous situation while driving. in some cases low power steering fluid may have trapped air in the power steering box or lines.have you checked the fluid level since you topped it up ? after running it you may find it down again as some air has purged out of the system and of course it may have been down because of a leak at this point I would prefer to drain and flush the system .
these systems are hard to get the air out of because the power steering pump is a long way from the power steering box and there's places it can trap the air at any rate I would suggest you speak to a good service department to get this addressed.

Some of these systems share the same hydraulic pump to run both the power steering and the cooling fan in these cases there is a priority valve which is supposed to maintain hydraulic pressure to the power steering unit during periods of idle or slow engine operation and priority to the power steering sometimes these valves can stick causing symptoms that you describe at any rate it should be looked after.

Hope this helps Eric

[Steve Huber Co-Admin]

Albert,
The 07 Contessa hydraulic system pump drives the steering and the fan as Eric suggested. The O'Reilly AW-46 appears compatible with Rando 46.
Steve

[Albert Balika]

Thank you all. I did check the level and topped it off with approximately a quart and one half. I can't imagine that was enough to create the problem, but not sure. I wonder if air got in the system when the hydraulic filter was changed 1200 miles ago and now found its way to an area in the system to create a blockage. If so, there a place to bleed air from the system? I am currently in Gunnison, Colorado and don't know any motorhome techs to flush system, etc. Did I do any damage to the system by driving it with this problem for approximately 75 miles? Also, would a mechanic familiar with hydraulics be able to flush the system, etc? Any help is welcomed.

[Albert Balika]

Steve, I am sorry I forgot to respond to your question. The answer is - I always drive with my exhaust brake on because I am usually in the mountains. Is this a bad idea? Your expertise is always valuable. Thank you.

[Joel Ashley]

I (and others) had a similar issue, but not as severe as you describe.  At <5mph parking lot maneuvering speeds the wheel would suddenly and almost violently jerk mid-turn.  As Steve noted, it was eventually subscribed to an overtaxed power steering system due to an association with the exhaust brake.  Simply remembering to leave the exhaust brake switch off when it’s not needed solved the problem. 

Rather than leaving the brake perpetually on as many ascribe to, I only use it where it was designed for, on downgrades where it saves wear on expensive-to-replace wheel brakes and protects against their fading dangerously from heat.  At times it may help limit brake wear in repetitive stop and go city conditions, but I find it clumsy and fortunately a relatively rare occasion.

Joel

[Albert Balika]

Joel, Thank you. I had no idea there is an association between the exhaust brake and the power steering function of the hydraulic pump. I am curious to know what that would be. In my instance, I was ascending and descending steep and long grades and had the exhaust brake on continually as I always have. Obviously, my speeds were far more that the 5mph you described. At speeds of 20mph or more I still had the problem, but not as severe as lower speeds in corners. I was able to back the coach into our space in Gunnison, but it took a great deal of strength to maneuver into the space. Do you think I did any damage to the system in driving for 75 miles with this intermittently happening?

[Steve Huber Co-Admin]

Albert,
Like Joel, I only turn on the exhaust brake when needed, descending long/steep hills and sometimes in heavy traffic where I may need extra stopping power. That said, your symptoms sound more severe so your problem may be with the power steering pump itself.
Steve

[Albert Balika]

Steve, Do you mean the "steering Gear" up front attached to the steering column, or the "hydraulic pump" in the rear at the the hydraulic fan which also drives the power steering? I found the grease fitting on the steering gear and it hasn't been greased for a long time. I get the chassis lubed every year and they did everything except the steering gear. I don't know if that would create this problem, but my guess is no. I would think this is a hydraulic problem. I also found what I think is a bleeder port, but not sure. It is towards the top of the steering gear and has what looks like about a 3/8 nut or bolt. If that is a bleeder, I am wondering if I might have an air bubble in the system. I am basing that on the discussion of the exhaust brake causing a steering problem. Since the exhaust brake is not part of the hydraulics, could it be heating one of the hydraulic lines enough to create an air bubble? What are your thoughts

[Steve Huber Co-Admin]

Albert,
Poor choice of words on my part. I meant hydraulic pump. After re-reading your initial post I have a couple of questions.
1.   You stated that you changed the hydraulic filter about 1200 miles ago and "all worked great". Thus, when did the current problem appear?
2.   Did the problem (when moving) disappear after you topped off the fluid? I suspect not if it still turned very hard at a standstill with engine running.

From what I’m understanding at this point, I fully agree with Eric that the first step would be to do a complete flush and refill of the hydraulic system. It could be air in the system or it could be a pump going bad. IMHO this is probably best done by a qualified shop.
FYI, if it is air or the pump failing intermittently you probably wouldn’t see a noticeable difference in engine temp if the fan shuts down for a short period in any case.
Steve

[Joel Ashley]

I agree that your symptoms are too strong to be simply due to the exhaust brake being on, Albert.  But just to explain the phenomenon I referenced, the application of the brake “chokes” the exhaust and thus engine power.  The reduced power is inadequate to the total needs of a hydraulics pump that runs both a cooling fan plus the power steering.  At highway speeds, the engine rpm is higher than in a parking lot or campsite, and is adequate then even with the exhaust brake on.  Your cause is likely elsewhere;  but regardless, leaving the brake on 24/7 is still not good practice.

Reference this pertinent thread:     http://beaveramb.org/forum/index.php/topic,8117.0.html
where Dave Atherton also explains why we shouldn’t leave the brake on all the time.

Joel

[Albert Balika]

Steve and Joel, The problem just started recently (in the last 75 miles). As I said, the filter was changed and fluid topped off 1200 miles ago and all ran well until this last 75 miles. I let the engine and fluid cool down overnight in 39 degree temperature. I checked the fluid level and it was down about 1.5 quarts. I topped off and started the engine at let it warm up, tried to turn the steering wheel in a stationary position which was unsuccessful. I looked at the steering gear and noticed the grease fitting had not been lubed and the dust cover was missing. I also found what I think is a bleeder port with a 3/8 inch hex nut. If, in fact, this is a bleeder port, I would think this is the first place to start, perhaps looking for an air lock. If that doesn't do the job, I will then pursue flushing the system as suggested by someone who knows hydraulic systems. Any other thoughts? Is that a bleeder port? Also, I do not have anything regarding part numbers for the hydraulic pump or the steering gear. Any guidance regarding these part numbers would be helpful. Thanks again.

[Steve Huber Co-Admin]

Albert,
I don't have my coach at home so can't look at the steering box on mine. I think that may be the bleeder port. If you decide to bleed it, be sure to run the bleed hose into a container of fresh fluid to ensure no air is sucked back into the system.
Also, if the pump is belt driven make sure the belt isn't slipping excessively.
No idea as to the pump mfgr/part#. Monaco used an European (Italian?) pump on some of the mid 2000 decade coaches that was very difficult to source for replacements.  See http://beaveramb.org/forum/index.php/topic,9999.0.html  for more info.
Steve