Thursday, September 17, 2020

Fixed at last. I hope.


The power steering and power brakes on the Rolling Steel Tent are interconnected in a system General Motors calls Hydro-Boost. Most commonly, power brakes are boosted by vacuum pressure generated by the engine. But with Hydro-Boost, hydraulic fluid is sent not only from the power steering pump to the steering gear, but also to the brake master cylinder. Then the fluid recirculates back to the pump. Typically, a fluid reservoir is part of the power steering pump, but in the van it’s a separate container.


Back in the spring of 2018 I noticed a puddle forming under the Rolling Steel Tent. Its source appeared to be a leak in one of the high pressure hoses between the power steering pump and brake master cylinder. I had the hoses replaced. The leak continued, but not badly. 

Convinced I had gotten a bad replacement hose, I went to have it replaced again in November 2019. The mechanic determined the hoses were fine and that the leak was actually coming from the brake master cylinder. I had it replaced.

During late winter/early spring, the van started making a moaning sound that changed pitch with engine speed. The moaning would subside whenever I topped off the fluid.

Then this summer the moan turned into a whine and fluid would leak right out. I limped to a mechanic who informed me the power steering pump and steering gear were both “puking fluid” and would need to be replaced. Okay.

When I picked up the Rolling Steel Tent, the power steering and power brakes failed as I pulled out of the car repair place. I struggled around the block and back to the shop. They replaced the defective pump, and I was back in business.

Except things didn’t feel quite right. The steering and brakes felt only partially boosted. And the moan was still there. I wondered if the noise was something else. The transmission perhaps? Ack! I hoped not. 

I managed to make it from Oregon to New Mexico without breaking down. But I needed to find out what was going on. Was replacement pump number two also bad?


Fortunately, the shop in Oregon was affiliated with NAPA and provided a warranty on parts and labor. Also fortunately, there’s a NAPA-affiliated shop in Silver City. I went in Monday to tell them my story. They gave me an appointment the next day to check things out.

Tuesday the mechanic confirmed the noise was from the power steering pump. (Whew, relief. I guess.) He also noticed the fluid return line from the brake master cylinder to the reservoir was kinked, restricting flow, causing starvation in the system, which was probably what destroyed the pump and steering gear. They ordered a new hose. I came back Wednesday to have it installed.

The service manager, mechanic and I expected the hose to have a bend molded into it, because that’s what the parts diagram showed. But it was just a straight piece. Test fitting showed it didn’t kink as much but probably would end up like the old hose over time. We came up with a solution. They found a spring that would fit inside the hose, supporting it like ribs.

With the new hose, steering and braking felt much more normal, but the pump still moaned. It had probably been damaged by fluid starvation. So it was replaced on Thursday. Under warranty.

Now the moan is gone and the steering and brakes work as they should. Hurray. Fingers crossed. Toes, too.

So, here’s what I think. Automotive parts change in small ways over the years. Sometimes there are tiny differences from one vehicle model to another, like between pickups and vans. I think it’s very possible the return line connection on the replacement brake master cylinder was in a slightly different place, causing the hose to not fit properly, creating the kink.

I don’t blame the mechanic who replaced the brake master cylinder, or the parts supplier. There are so many parts and too many differences to keep track of. And I don’t blame the shop in Oregon for not noticing the kinked hose. They were concentrating on the pump and steering gear, not the master cylinder at the other end of the system. The cost of the repairs (and hotel room while waiting) hurt, but when I compare it to what I had spent on house repairs over the years—new furnace, new air conditioner, removal of fallen tree, new roof, rebuilt retaining wall, and so on—it’s not so bad. And the van repairs happened while I’m generally very happy with my life. I was not a happy man when I lived in the house.


  1. Congratulations on your analysis. I think you did good, myself.

  2. It's hard to find good help. If/when in Albuquerque, I recommend By The Book. They're not cheap, but they're thorough and check their work.

    Letting you drive out thinking you're good to go only to have your brakes fail doesn't sound like a recommendation. Who are these people? I'd like to be able to avoid them.

  3. Express transmissions are tough, problems shifting alot of the time
    Are related to an inexpensive part
    Known as the shift modulator.