1993 Winnebago Chieftain 32’ p30 Chevy Hydro boost, park assist, brake problems

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Jehm101

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Could someone help me figure out what is wrong with my hydro boost, power steering and bakes please?

I jacked the front end up and turned wheels stop to stop 10 times and then brakes pumped 3 times with engine off and repeated this 5 times. I then turned the engine on and repeated the process again at least 5 times until it seemed like all the air was out of the system and the reservoir stayed at a constant level. I then lowered the front end and repeated the process again and almost immediately it went to **** again and air was introduced back in the system and the reservoir.

The best the system was is right before I lowered the front end and it seemed like it worked perfect from putting it in park and then drive and the parking brake turned off within a few seconds and the power steering did not squeal with turning the steering wheel and applying the brake in park and in drive.

I’m back where I started. When I start the engine in park and apply the brakes a few times it starts to whine and then turning the steering wheel it will also whine. I’ll put it in drive and sometimes the parking brake light stays on but the brake releases and sometimes the light goes out after pumping the brakes several times. It does not seem to be leaking or sucking air anywhere except at the overflow. I forgot to ad that I also bled the park assist. I do t want to start replacing parts if not needed but I have no clue what is wrong. Also the reservoir would get hot when the front end was down and I turned the steering wheel.

Do you think something has failed?
Do you think I need to try to raise up the front end again and repeat the bleeding process?

Thank you in advance,

Jehm101
 

Ex-Calif

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Thank goodness I don't have that system on my rig although I have read up on it briefly. I assume you have a P30 manual?

I will take a stab in the dark and call it a failing pump. The fact that it works no load is interesting but if the belt is squealing under load I guess pump. Have you had the belt off and turned the pump by hand and wiggled the pulley for end play and side play?
 

Lou Schneider

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Mar 14, 2005
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If the pump is putting out insufficient pressure this will show up when the system is under maximum load such as turning the steering wheel while the wheels are on the ground while simultaneously pressing on the brake pedal. Not at the full end stop as you want to feel the steering assist cutting in and out, not just cut out. You'll feel vibrations in one or the other as their power assists cut in and out.

Before you replace the pump, make sure it's pulley isn't stopping or shuddering when the system is under a load like the above. That's the first thing I'd check as it's the easiest. If it does, tighten or replace the belt so the pump operates smoothly up to it's cutout pressure and see what happens. A loose belt won't necessarily squeal at low engine speeds which is where the engine is usually operating when you apply the brakes.
 

Jehm101

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I did noticed a squealing belt noise a couple of weeks ago, I will get a new belt and put it on this weekend.

I’m just curious if I did get all the air out and there are no leaks, how can air get into the system with a bad or loose belt.
 

Jehm101

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May 19, 2022
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Location
03276
Thank goodness I don't have that system on my rig although I have read up on it briefly. I assume you have a P30 manual?

I will take a stab in the dark and call it a failing pump. The fact that it works no load is interesting but if the belt is squealing under load I guess pump. Have you had the belt off and turned the pump by hand and wiggled the pulley for end play and side play?
I have around 55,000 miles on the old girl and it seems like it was maintained before me. I’ll check the pump by hand tomorrow.
 

Jehm101

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Joined
May 19, 2022
Posts
8
Location
03276
Thank goodness I don't have that system on my rig although I have read up on it briefly. I assume you have a P30 manual?

I will take a stab in the dark and call it a failing pump. The fact that it works no load is interesting but if the belt is squealing under load I guess pump. Have you had the belt off and turned the pump by hand and wiggled the pulley for end play and side play?
I have around 55,000 miles on the old girl and it seems like it was maintained before me. I’ll check the pump by hand tomorrow
 

Jehm101

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Joined
May 19, 2022
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8
Location
03276
Today I cleaned up all the components and lines the best I could and then put carboard underneath everything, because im parked on grass, and jacked up the front end and continued to bleed the PS system. I tuned the wheel about 1 rotation per minute from stop to stop off and on for over an hour and pumped the brakes every so often. I had nothing leaking on the cardboard but this time because i went so slow, and had the radio off, i was unable to bleed the air out. when i got about one half to one quarter turn to stop on either end i could hear the air bubbling and then whining as i got close to the stops. Why cant i get the air out?
 

Skookum

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Dec 19, 2018
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This is just a wild guess. I had a Bendix hydro boost system in my super C, and even when it worked perfectly, it was very noisy. Not squealing. But you could always hear high pressure fluid noise when braking hard or turning and that was totally normal for the system, and it was completely purged of air.

If you're getting air in the system and you're feeling variable/intermittent levels of braking boost and steering assist it's because the system is no longer closed. Something must be leaking or not holding pressure. I replaced the fluid in my system a couple of times and the one time I let the fluid get too low while flushing it, getting the air out was as simple as you described. Turn the wheel lock to lock a few times while stepping on the brake with the pump running and it was purged.
 

Jehm101

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May 19, 2022
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Location
03276
This is just a wild guess. I had a Bendix hydro boost system in my super C, and even when it worked perfectly, it was very noisy. Not squealing. But you could always hear high pressure fluid noise when braking hard or turning and that was totally normal for the system, and it was completely purged of air.

If you're getting air in the system and you're feeling variable/intermittent levels of braking boost and steering assist it's because the system is no longer closed. Something must be leaking or not holding pressure. I replaced the fluid in my system a couple of times and the one time I let the fluid get too low while flushing it, getting the air out was as simple as you described. Turn the wheel lock to lock a few times while stepping on the brake with the pump running and it was purged.
A high pressure line on the control valve for the parking brake that I tightened and it stopped leaking started to leak again. I noticed the o ring was bulging out in one spot so I unscrewed the fitting to change the o ring and all of a sudden a few parts came flying out with a spring and I’m not sure if found them all or put it back together correct. I can’t find any information on it. It is the valve that engaged by the shifting lever. I then decided to take the low pressure line from the hydro boost that goes to the reservoir and flushed the whole system with prestone power steering fluid. I jack up the front again and started my turns and then all of a sudden after one turn the parking brake light went out and the whole system started to whine. I stopped the engine and of course all the fluid was foam. I decided to walk away and try again tomorrow. Does anyone know or have a diagram of the parking brake control valve attached to the shifting lever that shows what parts are inside?
 

Jehm101

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May 19, 2022
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I found all the parts but put it together incorrect. Here is a diagram for others who may need it.
 

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Ex-Calif

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Hang in there - You are getting closer, I think...

It's interesting to view the evolution of automobile control systems. In the late 70's my MGB got a seat module that was supposed to inhibit starting, run warning lights and so on. The module had a basic IC but everything else was mechanical.

Your system is a hybrid of "hydro-mechanical" - These days it's all solenoids.
 

Jehm101

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May 19, 2022
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03276
Come to find out, the shift activated control valve was stripped out where it was leaking and I need to get a new one.
 
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