LOL,, thanks,, there was some good stuff on this forem,. good way to start out the day with a good laugh

The engineer at Saginaw checked things out, and here's his final assessment:

"Rusty, I find this pump to be common with the this vehicle platform. We had made attempts to combine pumps of this vintage to reduce component inventories. Sometimes the tube orientation may differ from original equipment, but be acceptable for hose routing's. The performance of the pump is the same with the only difference being the tube orientations. "

Well, my diagnosis was wrong; the culprit isn't the P/S pump. However, a 250 mile round trip Weds-Sun proved educational.

To summarize, the initial symptom was when the engine was shut off, the P/S reservoir would overflow due to aeration. I suspected the P/S pump was drawing air in around the shaft seal, but that wasn't it, as the symptom presists after replacement.

However, after stopping at the star party, I checked the fluid level; half on the dipstick. After sitting four days at the star party, the reservoir was completely full!

The only thing in the system higher than the reservoir is the brake booster.

Tomorrow, I'll contact the Nexteer (nee: Saginaw) engineer, and find out if there's anything I've overlooked.

I haven't heard back from the vacationing Nexteer engineer.

I had the brake booster and master cylinder replaced (3rd time for the MC) I decided to go ahead and do both as the MC was leaking, and it was easier with the MC out.

Still seem to have the foaming problem. I have one more thing to fix, but I doubt that's the problem. I do need to do a proper bleed on the brake booster...but I don't think that's the underlying issue.

quote:

Originally posted by Bill N.Y.:
How is the suction side hose? A slight crack, like in a soda straw, doesn't show up until a suction is present and you'll never see a leak because fluid is thicker than air. This means that a suction side hose can suck in air well before it'll (if ever) show up as a fluid leak.

While you're throwing money at it Rusty... Just replace the suction line from the reservoir to the pump.

The brake booster was a "mightswell" - the MC had to be replaced, and since it's such a rotten job, I had the booster replaced while it was out - saved about $200 labor.

I don't mind replacing; the brake booster will be kept as an onboard spare, as will the other parts.

SInce the return lines are buried in the frame rails along with 20 other things, I was hoping to avoid the returns...but that's all that's left.

Where is your hydraulic reservoir tank? Where is your pump? How long is the hose between the reservoir and the pump? Is there a fitting between the reservoir and the pump that has wires going through it? Is there any fittings on the reservoir tank and the suction side of the pump that has o-ring seals?

Good luck Rusty!

Bill,

Is there a separate hydraulic reserve tank on the hydroboost brake systems? I've had several GM vehicles with hydroboost and didn't know that but it sure makes sense....actually before I knew that, I had thought it might be expedient to add one for safety..
Thanks,
K&E

The hydro boost operates from the power steering pump and reservoir. It provides the mechancial advantge to apply pressure to your normal brake master cylinder. A failure of a Hydro boost only removes the power - it does not make the brakes fail. A leak or low brake cylinder will still get the power boost and if you have a leak it will get worse. Sometimes the brake master cylinder can only be acessed thrugh the floor under the drivers seat.

quote:

Originally posted by Bill N.Y.:
Where is your hydraulic reservoir tank?

About 18" above the pump. Has about 24 oz cap.

quote:

Where is your pump? How long is the hose between the reservoir and the pump?

Left front of engine (Right rear of coach). Hose from reservoir to pump is about 20".

quote:

Is there a fitting between the reservoir and the pump that has wires going through it?

No

quote:

Is there any fittings on the reservoir tank and the suction side of the pump that has o-ring seals?

No. All friction (barbs/clamps) or flare.

quote:

Good luck Rusty!

Thanks. I ran in place yesterday; the reservoir was full I stopped it after 5 minutes, and the reservoir didn't overflow. However, it may take more exercise of the system to recreate the issue. If it's cured, the brake booster may not be completely purged.

One symptom before was that the reservoir level rose while it sat for a few days. I'm not going to do anything until Monday, so I can see if the level rises. If not, the issue may be cured.

I had hoped to hear from the Nexteer engineer whether the suction side of the pump could operate at less than atmospheric pressure. On another forum, a very knowledgeable guy says that the return side is always above atmospheric.

quote:

Originally posted by Rusty:
Left front of engine (Right rear of coach). Hose from reservoir to pump is about 20".

Replace the 20 inch hose. This is the suction hose.

quote:

Originally posted by Rusty:
I had hoped to hear from the Nexteer engineer whether the suction side of the pump could operate at less than atmospheric pressure. On another forum, a very knowledgeable guy says that the return side is always above atmospheric.

How much have you thrown at this problem Rusty? We're talking about a 20 inch hose. Not really a bank breaker. Besides... who you going to believe... Some engineer or someone who has repaired these issues in the past?

quote:

Originally posted by Rusty:
SInce the return lines are buried in the frame rails along with 20 other things, I was hoping to avoid the returns...but that's all that's left.

Not the return lines Rusty as these are above atmospheric psi.

I replaced the 20" hose when I did the PS pump. I'm going to bleed the booster at its return. I did find a useful guide for bleeding on the web.

The reservoir has two lines going to it - one has to be a return from somewhere.

I'm hoping the remainng issue is to bleed out the system - I had benn doing it wrong, or not as effectively as could be.

I seem to be making progress, as I added fluid today, and it spit out significantly less. Steering and brakes responded batter oin startup, as did the shaft brake.

Gonna let it sit 'til Monday, see if the resevoir level creeps up like it dis before.

Rusty: RE...... Bleeding brakes...Your post on February 26 # 4037.
Will you discribe in detail how you would (or did) bleed your brakes?
Thanxx................

Carl, my system is entirely different from yours. Mine is Hydroboost (Hydraulic over hydraulic); yours is air throughout.