I just got a 1994 motorhome built on a Chevy P30 chassis. I was told the problem with the systems was low fluid but after getting it home then moving it around a few days later the system acts intermittent. It works but is noisy then for a few minutes no power steering or brakes. The noise is like low fluid in a power steering pump or one that is working hard. Any suggestions other than replacing the pump and lines.
If the fluid is low, it will aerate and look like it's full. Can you check the fluid level with the engine running, very soon after a cold start?
In reply to zordak :
We had a 94 Suburban with the 6.5 diesel which had the hydro boost. Pretty simple system. Ours sprung a big leak while out of town. Just replace the ps pump & should fix it as long as it's not losing ps fluid somewhere
I've never owned a hydroboost GM that didn't have a whining PS pump. I replaced a noisy one once with a reman and it still whined. Thinking I got a bad rebuild, I returned it and bought a brand new GM pump... and it still whined.
The system is pretty simple. If you're losing both steering and brake assist, I gotta think it's a toasted pump.
On my P30 motor home I had issues with spongy brakes and questionable steering. A couple of things helped.
1. replaced the master cylinder gasket. Mine was just too hard to keep it sealed under pressure apparently.
2. Airlift helper springs on the front. These were a BEAR. Honestly one of the more difficult things I've done on a vehicle oddly. I believe I boiled the second one before installing and it helped a ton. Regardless, the factory springs on Lu motor home were underrated and bound the suspension and overworked the power steering. This change along with new tires changed the driving experience from literally white knuckles and sweating- to one handed cruising.
It sounds like a failing pump.
One thing to check, though, is with the power steering system functional and good assist, shut the engine off and apply the brakes. You should have 2-3 brake applications minimum before you run out of brake assist.
If you have no assist unless the engine is running, the accumulator in the brake booster has failed. This will accelerate pump wear because it stresses the pump every time you apply the brakes. It is a little like how a bad battery puts a lot of stress on the electrical system, nothing to cushion instant loads.
I'm posting so I can more easily follow and learn. Nothing to add.
O.K. I am going to do a little research on the proper bleed procedure for this. ( I think it is just turn the wheels side to side a few times) and see what this does. Good point about the accumulator I will check that out also.
Jack up the front and cycle lock to lock several times with the engine off. Then start the engine and leave the wheel centered. The little bit of pressure that sneaks past the valve will hopefully push any bubbles out of the box.
Then with the engine running, go lock to lock several times, still jacked up.
If you do it with the tires on the ground you potentially have 27,000 psi of fluid pushing through things which is when you get the air bubbles turned into mousse.
Curtis73 (Forum Supporter) said:I've never owned a hydroboost GM that didn't have a whining PS pump. I replaced a noisy one once with a reman and it still whined. Thinking I got a bad rebuild, I returned it and bought a brand new GM pump... and it still whined.
The system is pretty simple. If you're losing both steering and brake assist, I gotta think it's a toasted pump.
pretty sure all of them leak too.
Has anyone tried putting a vacuum on the power steering pump to make sure you've got all the air out?
That's cured my whining Ford PS pump.
I don't know this system but if it has a remote reservoir and there is an air leak in the feed it will whine. The air leak can be so minor fluid doesn't drip out when it is off, but with suction from the pump a little air leak causes problems. Fun!
I took a few minutes last night and started it up and turned the wheels lock to lock a couple of times. (yes with the wheels on the ground) I did not burp any fluid out, was still a bit noisy but did not stop working. When I get it registered I plan on taking it out for a drive and try to get it to fail again. If it is like last time it will be when I am maneuvering it to back in to the driveway. If it does not fail I think it was just an air bubble, if it does I'll look further.
Registered. Tried to go for a drive. I did not get all the way out of the driveway. Crawled underneath and looked around and found the brake rod is covered in power steering fluid. I need a new hydro boost. Can I just replace the hydro boost and not the master cylinder? If so anything I should be aware of?
Yep, have done it all the time.
O.K. Spent the weekend wrestling with this, and now have a rebuilt hydroboost in it. After bleeding and a test drive the pump noise went way down, and no leaks.
That's got to feel great. Nice job. How long did it take and was the motor home aspect a benefit or an obstacle?
In reply to zordak :
Nice!
I took around 4 hours on saturday, I got a late start due to morning rain.(I don't have a garage a motorhome will fit into) and another 8 on sunday. Being a motor home definitely made it harder. I was not able to get the shroud completely off due to a screw that there was absolutely no access to. I thought about snaking a wheel of death up there to cut off the weld nut, but decided not to risk it, and just bend the shroud out of the way and got the job done but would have been easier with the shroud out of the way.
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