When I started my truck a couple days ago to drive it to the fab shop, I had no power steering. In fact, it felt like I had worse than no power steering. By the time I idled down my drive to my house (maybe 400 feet at most) the steering improved but it was not like it should be. I popped the hood to have a look and there was fluid blown all over the place around the power steering pump. I checked the reservoir and it had fluid. I had my father hop (well, at 68 he doesn’t hop anymore, but you get the idea) in the truck and turn the wheel while I watched the power steering pump and there was no leak and he said the steering felt fine to him. After driving the truck up to the shop (15 miles), I checked again and the reservoir was dry. I added the specified Dexron III Mercon ATF to the reservoir and started the truck and had my father turn the wheel again. A small amount of clear fluid (just a few drops) appeared on one of the hoses, but that was it and the steering worked well. The clear fluid smelled like brake fluid to me, not automatic trannny fluid. I continued to work the wheel back and forth and no more fluid appears to be leaking.

Any idea as to what the heck happened and why? Because it was pretty cold (for here... 18 degrees) and the truck hadn’t been started in a few days, I’m wondering if a small amount of water didn’t settle in the pump or a line somewhere and prevent the thing from working properly. I’m also wondering if some shop the truck has been to recently might have put brake fluid in the system which could have caused the seals to do unusual things.

I’m stumped as usual with this truck and its gremlins and I’m open to suggestions.

 

I doubt I can help, but you mentioned adding the specified Dexron. My ISX steering uses 15W40 motor oil.

 

The reservoir bottle has molded right into the plastic to use only Dexron III Mercon Automatic Transmission Fluid.

My 2003 CAT C15 took (according to Peterbilt because nothing was listed on the reservoir) either thirty weight motor oil or hydraulic fluid, which ever you preferred.

 

It wouldn't be an ISX issue. Power steering is an OEM system; nothing to do with the engine. I don't know what may have caused your problem. In my experience, steering is always a little sluggish on startup in cold weather; at least until it gets warmed up. I DO know that we try to rebuild or replace pumps somewhere in the 500,000 to 750,000 range. I don't think your idea about ice is implausible, especially if you've got some worn seals that allow moisture migrate into the loop.