I have replaced the engine and most of the accessories. The power steering pump was OEM and so are the lines. These coaches have the (in)famous Hydroboost power brake system. The pressure from the power steering pump is also used to provide the power boost to the brake system. This makes the power steering pump and belts critical to both steering and brakes.

The original setup had 3 belts on the pump but only one dedicated to the pump. The others ran the AC and AIR smog pumps. I removed the useless devices some time ago and I have 2 dedicated belts for the pump. I am happy with the belt setup. With that in mind I was motivated to finally replace the aging pump and lines.

The system is located in a miserable location down low on left front of the engine. If you have the AC compressor above it will be really hard to get to. I abandoned the OEM AC system and it pays off for me here.

Here is the GM diagram of the system:



There is a high pressure flex line from pump to brake assembly. From there a steel pressure line runs to the steering gear. Both the brake assembly and the steering gear have low pressure return hoses which go back to the main pump reservoir. Finally, the reservoir has a hose connected to the remote filler tank.

Once the AC is out of the way you can get to the pump. (It is not necessary to remove the fan and pulley, I was also changing the water pump) The adjustment bracket and the lower pivot bolts must be removed.





The old pump had 3 grooves on the pulley. I am only using 2 so I bought both a replacement pump and a 2 groove pulley. I will keep the old pump assembly for a spare. When you order a pump be sure to get the motorhome/Hydroboost pump. It has higher ratings than the generic V8 pump.

Pump: CarQuest PSC 20-8713 (Reman DOM P/S Pump)
Pulley: CarQuest DOR 300-121 (Dorman)





Once the new pump has the pulley mounted you can reinstall the pump and belts.



Now for the hoses:
The OEM high pressure flexible line runs from the pump to the brake assembly. I got one from CarQuest that fit right in. (PSH 36177)



There are 2 more steel lines. One is a high pressure feed from the brake assembly to the steering gear, with different sized O-ring flares at each end. The other is a low pressure return line, with O-ring flare at one end and hose barb at the other. Both lines were very rusty.

I decided to paint and reuse the low pressure return line but I didn't trust the rusty pressure line. I was not able to find a ready replacement. I ended up fabricating a new line. I used 2 tubing service kits which had an O-ring flare on one end of an 18" steel line. (CarQuest DOR 800-153 Dorman brand) With a tubing bender and a splice connector I was able to combine the two pieces into a suitable replacement.

WARNING: The compression fitting supplied will not take the pressure. Use a flare fitting or do as I did, solder the connector and tubes together solid. The photos do not show the soldered connection, I took them before I pressure tested the system.



Replaced all the hoses except the filler hose (for better view) I used ATF cooler hose for the flexible return hoses. You can see one end of the new pressure line and the splice in the background.



From below. Steering box bottom center. Blue cylinder upper right is the Hydroboost pressure reservoir. Again, splice in line is visible.



I will fill the system, bleed air a few times, should be good for long time.

DISCLAIMER: I often order parts online, usually from Summit. When I need oddball parts I usually get them from CarQuest here in town. They are convenient, the parts guys are oldtimers who get the right parts almost every time. They also have the only remaining machine shop in the area. I know the owner and I like to support the business. I have not had any problems with the parts I get from CarQuest either. Nothing against the other suppliers but I'm happy with CarQuest here.

You're right about the wretched Hydroboost system - no P/S pump, hard steering and weak brakes.

I had the belt break on my SOB just taking it home from purchase.

On the Barth, I've had 2 master cylinder failures (oddly enough, both on I-95, within a couple of miles of each other 3 years apart), and both replaced at the same shop in Baltimore. Then there were 2 Saginaw/Nexteer P/S pumps which sheared their shafts. And 5 belt failures, one of which was caused by A/C compressor seizure and the others by not replacing the damper pulley.

Loss of the system isn't catastrophic, but it does involve using muscle power.

As I suspected while installing the compression splice connector, that is a lot of pressure for compression fittings. Sure enough, it leaked.

I removed the line, cleaned in solvent, fluxed well and soldered the connector and tubes together solid with a torch. Live and learn. Use a flare fitting or solder together. I edited a warning into the original posting.

I've found that soldering the bead is usually enough to make a compression fitting work (who invented that abomination, anyway?).

I would like to thank Steve for this post. It was very enlightening.Since I have owned my Barth it has never felt like I was getting power brakes. Power steering works fine.Early on I had the booster replaced as the old booster was leaking. It was done at a small garage in a small town and they said that they think that they had it bleed well. That was with the air conditioning pump in place, and the radiator and shrowed. It was very hard to work on .I have since opened everything up, and can see what is what, and it has brought up some questions. Do you think that the pump needs two belts. My alignment is such that the front pulley on the pump lines up with the back pulley on the water pump.So I can't run doubles including the water pump. I could however run just from the crank pulley to the pump with double belts. And how do you bleed the power brake side of things. Also what is that small tank lying on the cross member, and that small junction block with the little yellow handle.So many questions. I took some pictures, but they come through large, and I do not want to overload anyone.

I am running the 2 belts directly from the crank pulley. A bit tight to get the belt under the water pump but mine clears OK. You can run on one belt OK but keep an eye on it more regularly for wear, etc.

If you want to email the photos to me I can post them here for you. svanwesten2@yahoo.com

I think I will leave it that way for now. I would like to upgrade. I noticed that you have a serpentine belt for the alternator.I would prefer that for the pump as well. Is that a checrolet aluminum intake on your engine ? I am replacing castiron parts with aluminum, as I go. I would love a supercharged all aluminum 454. Some day. For now I have to attend to the tasks at hand. I will send some pictures.

Interesting photos from Iam:















Looks like it is the belt setup from 85 or older. Serpentine belt was first used in 86, I think. The round canister looks like a fuel filter but it is not in the usual location… maybe an aftermarket filter in the power steering system? Sometimes they are added to prevent damage from circulating dirt.

Also, your master cylinder is a bit different. Both lines attach near each other mine were farther apart.

Food for thought.

Hello,
I came across a Chevrolet service manual for light duty trucks, and they consider the P30 light duty.
The tank is an accumulator, a safety device that stores up to three brake applications under pressure, if the pump fails. And you do not bleed the booster system as much as purge it, by operating the steering from side to side, and pumping the brakes.So much to learn. It is a very informative service manual made by Chevrolet. How to interprate the numbers and letters of the vehicle ID , and such.

There are many attachments for downloading here:

https://www.barthmobile.com/eve...31087061/m/145102933

Includes wiring diagrams and service manuals for 1986 P30, among others.

Sorry for responding to a 3 year old post but I think it important should a search direct others to here -

A big Thanks to Steve VW for posting the information he found as well as pictures of the P/S pump to Hydroboost hose. After days of searching, I was unable to find it anywhere until coming across his posting. The local Chevy dealer was of no help either.

I've got a 1990 P30 (37 in the VIN) chassis w/454, under a 1991 Champion Ultrastar. Shortly after acquiring YellieBelle last year I took the old leaky hose off. With no success for finding a new replacement at the dealer or local parts stores, I had the hose remade. I was hoping that would fix the leak, but turns out the hydroboost was leaking as well. After recently replacing the hydroboost, it looks like the hose continues to have a very small leak - I suspect in one of the tube ends. It could probably be brazed closed assuming the leak is far enough away from the hose - but why worry if a new hose is $25 or less.

FWIW - based on continual research, it appears the hose comes from a 1989 P30 chassis.

Thanks again!

And a "Thank you" to you as well!

One of the reasons I try to document my work and use a descriptive thread title is so that others can find the info and not have to reinvent the wheel. It appears that ths is exactly what happened and I am pleased to know my efforts have helped.

Thanks for taking the time to let me know.

Good luck with your coach. Search around this site you may find more good stuff. I have threads on brakes, engine, transmission and there are many more by others as well.

I agree - this site has s a good one for those of us with Chevy P(