86 Chevy Steering Problem

[xtrememotives]

1986 Chevy 2500 K20 6.2L Diesel 100k on odometer 50k on rebuilt

Problem: I have very little steering which is completely lost when hitting the brakes. You can rev it up but it only helps for a split second.

_______________________

I'm aware of the bulletin:

"Please follow normal diagnostics in SI2000 for this condition. If vehicle passes the Power Steering Pressure Test Procedure this may be a normal condition. A lack of steering assist could occur if the brakes are applied and turning the steer wheel with the vehicle stopped or during parking lot type maneuvers . No repairs should be attempted as this is a characteristic of the vehicle. Any customer concerns should be referred to the Area Vehicle Manager (AVM) and a Field Product Report should be submitted by following bulletin 02-00-89-002C"
________________________

When I first purchased the truck I didn't have the problem I am having now, just looking to get back steering I originally had.

What have I done (other than review 10 pages of forum threads)? I have replaced the power steering pump and hydro-boost 3 times and the gear box twice and a new pitman arm. All parts are brand new and just finished bleeding the lines.

• 
  There is no whining, grinding, or chatter.
  There were no leaks to begin with and none now.
  The truck has new brake lines.
  I do not get power steering back at RPMs above 1100

 

[HotRodPC]

Are you referring to power steering? And it changes a bit if you rev the motor? Sound like maybe your PS pump has gone bad.

 

[HotRodPC]

After realizing you're female Anna, I had to change my last response. Sorry if you had seen that.

But then reading the complete post, I'm leaning more towards a defective gear box. If you're not getting any whining, and the power brakes are working fine, safe to assume the pump is likely OK. Believe it or not, and sadly, it's not uncommon to get a defective rebuilt gear box.

 

[chengny]

Is this a stock set-up as far as you know?

Is there a cooler (or a filter) in the power steering/hydro boost hydraulic system?

You didn't mention the hoses in items that you have changed. Did you renew any of these - or are have they been inspected and found to be in good condition internally? Do they all allow a full flow of hydraulic fluid?

There are four hoses associated with a stock set-up:

1. The pump discharge to the HB unit (HP)

2. The HB unit outlet to the steering gear inlet (HP)

3. The return line from the HB unit to the PSP reservoir (LP)

4. The return line from the steering gear to the reservoir (sometimes this line is tee'd together with the return from the hydroboost)

It sounds like flow through the return line is restricted. Problems with reduced steering and brake performance are usually due to poor return line sizing. But since yours used to work, it probably is not the size that is the problem, but rather the condition of the hose. The internal walls may be partially collapsed. This chokes the return of hydraulic fluid from the hydro-boost unit back to the PSP reservoir.

I would pull, inspect (and renew if necessary) all the hoses. Do this in a - one by one - fashion. This way you will save money on unneeded parts and also you will be able to see if there is a sudden improvement when a particular hose is renewed.

 

[chengny]

I have replaced the power steering pump and hydro-boost 3 times and the gear box twice and a new pitman arm.

But not the interconnecting hoses right?

 

[xtrememotives]

Thanks for your advice

I have been checking my email like crazy thinking if anyone responded I would be notified. So very happy to have some responses. I was on the verge of buying a $100 gauge to test the pressure on the pump since I haven't made any progress on solving this problem.

Will go buy new lines now and see if that might do it. Visual inspection of the lines really doesn't tell you a whole lot and I haven't replaced them before. Will let you all know what happens.

 

[highdesertrange]

when I had this problem it was the valve on the back of the pump sticking. where the high pressure line attaches to the pump there is a pressure valve, if the valve sticks you get no pressure. keep in mind you could have a bad hose. which could cause the same problem. highdesertranger

 

[xtrememotives]

Or my pump could be missing the valve and spring all together. The last pump I opened up and it was missing it too. So I ordered a new one 2 weeks ago and put it on. When I went to pull the hoses as everyone suggested I went ahead and looked, not there. I just got back from returning it (and the gear box core) to the part store and ordered power steering pump #4. I have looked everywhere for just the valve and spring. Does anyone know where I can get one as I do not expect the one I ordered tonight to have it either.

 

[xtrememotives]

Update

I got a pump for a different truck, pulled out the valve and spring, and we are back in business! Can turn the wheel with 1 finger once again. Thank you guys for all your help!