mc-8 Power Steering

[DavidInWilmNC]

As I mentioned in another thread, I'm trying to get my bus ready for a trip this next weekend.  Yesterday, while I was charging the A/C, I noticed oil dripping from the power steering pump reservoir.  It looked like it was coming out of the top... I guess that's the vent.  I had a leak somewhere last year when I drove it to Timmonsville, but I tightened up a couple of clamps that seemed loose and it appeared to quit leaking.  When I topped it off last time, I believe I over filled it, but I didn't think that would really matter.  What was strange is that it would leak a small but steady stream for about half a minute, then it would stop for a few minutes.  Then it would start leaking again for a bit, then it would stop.  It went through this cycle for about 30 minutes or so.  I believe it finally stopped leaking by the time I was through with the A/C.  It did seem to be providing assist to the front, but I didn't want to turn the wheel too much and grind the tires farther into the ground.  I noticed when I turned the steering wheel that it groaned some like an old Ford Ranger that I used to own.  So, my question is whether or not I should be concerned about this.  It did seem to stop dripping, but the fact that the leak came and went made me wonder. 

On the other hand, MCI sure made changing the radiator blower belt easy with that air tensioner.  I couldn't have imagined a belt being easier and quicker to change than a headlight bulb! 

David

[Sojourner]

Air bubble in power steering fluid thorough lines will expand while under pressure to cause fluid's level to rise & over fill to leak thorough vents. And guarantee to "groans" due to fluid (non compressible) & air bubbles (compressible) vibrating in line circuit from pulsation of gear or vane pump.

To relieve large air bubble...jack up front axle so tires are off surface to keep power steering pressure at lowest as possible to avoid micro bubble or foam in PS fluid. With engine running at low idle RPM, turn steering wheel both ways....Caution, it is important NOT to turn fully stop to stop that would cause pump to go high line pressure...otherwise you will be spending a long...long...long time removing air bubble fully. However after you have done the above, you may have gotten most of large bubbles out but there will be micro still in fluid until many miles later and several over night rest so micro bubble in reservoir rise to above fluid level to escape thorough vent. This is normal operation to remove bubbles for being too low fluid level to suck in air.

Or...You can replace fluid with non foamed oil (new) but still need to do above procedures to remove all air out BEFORE any high pressure work via having wheel on ground & full turn in either direction.

Either you or someone keep checking fluid level that it always at least half full to sight glass to avoid adding air into fluid. While air is being remove it will need to add fluid.

Do you have manual? It tell what fluid to use. If not get one very soon. Mine is a reprint....not very sharp to read but better than nothing. Someone on this board may know a better source.

FWIW

Sojourn for Christ, Jerry

[DavidInWilmNC]

Hi Jerry,

What you say about sucking air makes sense.  At one point it wouldn't provide any assist, so I know it was really LOW.  I have the manual and it says to use 30 weight engine oil in the power steering system.  I may just keep checking it on our trip and let that work out the air bubbles.  Our soil is very sandy here and it's a real pain go jack it up, as the jack sinks into the ground.  I won't be moving it 'til the trip, so that's pretty much going to be my option.  I imagine a 700 mile round trip will work out most of the bubbles.  I hope that I've got the leak fixed, else I'll be stopping about every 90 minutes to add more fluid (oil).  Thanks.

David

[Sojourner]

Hi David:
In time it will clear up after may over night shut down...in the mean time try to avoid having PS doing the stand still steering, if you can...try rolling start before steering and avoid turning steering wheel to full stop until all foam is completely gone. Again keep checking on PS sight level as well engine oil check.

About type & SAE grade of oil.....yes, they say use non detergent 30 weight if you don't have any leaking seal near spool valve (proportional valving). Otherwise use 40 or 50 (if not in freezing climate) weight or replace it if still leak more than you like.

Whatever you do...never use "repair leak for transmission & PS" additive to PS oil....it contain seal softener such as like a mild brake fluid within. It will work but seal get too soft that it will wear very quickly as well hose's inter liner deteriorates & collapse to shred.

Been there & done many customer repairs.

FWIW

Sojourn for Christ, Jerry