Hard power steering

[firefighter]

I'm in need of some power steering input, advice or direction.

My truck is a 1976 Chevy 3/4 ton 4 wheel drive with a rough riding 4" lift kit. I did a total sheet metal restoration 2 years ago and posted the progress here in our build section. The truck has had no issues since then and I'm still excited about driving it.

Ok, A few weeks ago I heard a slight knocking in the front end of my motor. I had just gotten back from a trip to the country so the suspension and steering definitely got a work out.
Come to find out, the crankshaft pulley was loose, causing the knocking sound, so I had to remove the power steering and alternator belts and remove the fan to get to the pulley bolts. No big deal.
Ever since I put it back together, the power steering has felt harder or stiffer to operate. This thing is so simple, you really can't get the belts on wrong but I double checked everything again, but no change. I even jacked up the front end to get the tires off the ground and it still feels like the power steering is definitely more difficult than it was.
When driving around in town, it doesn't quite feel like manual steering though. It just feels stiffer or sluggish.
Well then I started resorting to eliminating other things. I disconnected the steering shock thinking maybe is had gone bad. No change.
The next cheaper thing was to replace the power steering pump. That was kinda interesting in itself. The only thing my auto parts store had available was just the interior pump and you keep and reuse the metal shell of your original. It may (or may not) be a bit easier now, but I'm convinced it's still not back to how it was before. It still feels like "harder" power steering.

Anyone have a ideas what's going on with this crazy thing?
I will say that when I rebuilt the truck 2 years ago, the steering box had a bit of play in it, so I gently tightened the adjustment screw. I didn't tighten it much... just took a bit of freeplay out of it. It's acted fine for 2 years.
Has anyone ever had a steering box go bad? Is it possible? Could something have happened while going down the rough roads that day and affected something inside the steering box?
I just don't know what else to look at or try.

Help !!!

[zieg85]

My 85C30 acts like you are describing, almost binding, dragging kind of, harder both turning straight or straightening out.  My 85C20 seems very normal to me while my 84C30 turns so easy it is scary.  I would try flushing the steering box.  My 85C30 is going to get the box off my dearly departed 87GMC I recently parted out.  That one steered like it supposed to.

[bd]

You might have a bad hose or sticky flow control valve.  Was the steering okay right up to the moment you removed the belts to secure the crank pulley?  Any chance the reservoir or return hose bib was damaged?  Does greasing the front end help any? 

[firefighter]

Thanks for the replies so far guys.

When I put the new power steering pump in, I of course put new fluid in and bled the system. After running it for a bit I sucked out as much fluid as I could and then refilled it with fresh again. The fluid looks very good now.

Good point bd, after having the truck out for the day, I came home and noticed the knocking noise so I pulled it into the garage to take a look. The steering seemed fine then and I noticed nothing different. I really did nothing but pull the belt off to get to the lower pulley. When I put the belt back on and started it up and backed it out of the garage, I noticed it right away.

The problem definitely came on very suddenly.
No hoses or fittings are damaged or even touching anything.
Where is the flow control valve?

[Greybeard]

Prolly isn't the problem but might want to check just because. See if the box and frame are still tight together and not cracked. I had the box on my 78 break the frame and it got real hard to steer.

Then check the rag joint. It isn't the rag joint but check it anyway, just for fun. I had one of those give up on me on the truck I have now. Luckily it happened when I was in the driveway at work. Steering got REALLY easy real fast.

[bd]

...Where is the flow control valve?

It's under that enormous nut protruding from the back of the reservoir that the pressure hose threads into.  My thought on a bad hose was limited to the potential for a flapper that restricts fluid flow.

[firefighter]

This is a picture of the pump that I replaced. You keep your original metal power steering shell and just replace the inner pump. The nut coming off the back that the pressure hose screws into is removable and then there is some kind of slider with a spring behind it. Fortunately all these items were replaced when I replaced the pump and the problem still exists so I don't think they're the problem.

[bd]

Here's the model-specific information I was able to find in our Technical Pages...

GMC Integral Gear Power Steering (Training Manual)

1976 Service and Overhaul Manual - Section 3 - Front Suspension (page 3-1 (pg 45)) and Section 9 - Steering (page 9-1 (pg 365))

1977 Unit Repair Manual - Section 3B - Steering (page 3B-7 (pg 49))

The year-specific manuals mirror the training manual.  The information is kind of bare bones, but may help. 

[firefighter]

Thank you very much for the reply and for taking the time to attach the information. I really appreciate it.

Let me ask, has anyone every had the high pressure supply hose go bad or have restricted flow?
Has anyone ever had the steering box go bad where it made steering hard?

I have no problem changing things, but I suppose some things seem more logical than others.

To isolate the steering box and pump from the actual steering linkage, I guess I'd have to separate the two by possibly removing one end of the drag link just to see how the hard the steering turned not being connected to anything?

It seems this is something that people just don't run into regularly.
It's the craziest thing since it happened quickly and only after removing the power steering belt and then putting it back on. Very odd indeed.

Thanks again guys and I really appreciate any more input.

[bd]

...has anyone ever had the high pressure supply hose go bad or have restricted flow?
Has anyone ever had the steering box go bad where it made steering hard?

I have no problem changing things, but I suppose some things seem more logical than others.

To isolate the steering box and pump from the actual steering linkage, I guess I'd have to separate the two by possibly removing one end of the drag link just to see how hard the steering turned not being connected to anything?

It seems this is something that people just don't run into regularly....

In 30+ years as a GMC line tech and then service manager, I've seen only a handful of hoses fail internally and cause flow restrictions.  I've seen plenty of pumps fail, but only a few boxes fail from internal leakage. 

Separating the drag-link is suitable to check for binding with the wheels off the ground.

[Greybeard]

I believe the recirculating ball worm may have finally given up. I did have a steering box go bad but I never opened it to see how; back then junkyard parts were plentiful. I know the boxes are made really tough but nothing is indestructible. As for how fast it happened? IDK, but there is a boatload of hydraulic pressure running through it.

Off subject a bit but I have a Oliver tractor that uses hydraulics (for those city folks that may not know a tractor from a combine) the hydraulic unit runs off the the final drive gears and isn't much bigger than a power steering pump actually. It runs at 2000psi. I replaced mine two years ago. One day it was running perfect, no noise, good pressure, nothing apparently wrong. The next day after I started it it began a slight, barely audible squealing and before I could make the trip of about 100yards to the shed it gave up completely. A matter of about three minutes from start to dead. Granted it made noise, yours didn't. So I put this out as a possibility only.

On the other hand maybe the pulley is loose and slipping on the pump? I forget how the pulley is attached right now, I know it uses a puller to get them off but don't remember if it's keyed, interference fit or tapered. Any one of those ways can slip. The keyed one is just a little harder since the key has to be sheared first. 

[VileZambonie]

1) Ensure the belt is tight - The PS belt can slip very easily without making noise.
2) Ensure the flow valve inside the fitting is clear. (Just an FYI, next time just buy a reman pump with the housing)
3)When you turn to full lock does it put a strain on the engine? If so it's probably time to replace the power steering box.

http://forum.73-87chevytrucks.com/smforum/index.php?topic=14512.msg111777#msg111777

Directions for pressure test

All tests are made with engine idling at normal operating temperature. Check idle speed adjustment and, if necessary, adjust to correct specification.


1.Place a container under steering gear or pump.
2.With engine Off, disconnect pressure hose at steering gear or power steering pump, then install J-5176-D to both hoses using adapter fitting No. J-5176-20 or equivalent. Gauge must be installed between shutoff valve and pump.
3.Open shutoff valve.
4.Remove filler cap from pump reservoir and check fluid level. fill pump reservoir with power steering fluid to full mark on dipstick. Start engine and, momentarily holding steering wheel against stop, check connections for leakage. Do not hold wheel against stop for more than five seconds as pump can be damaged internally.
5.Bleed power steering system.
6.Insert thermometer No. J-5421-02 or equivalent in reservoir filler opening. Move steering wheel from stop to stop several times until thermometer indicates that hydraulic fluid in reservoir has reached a temperature Of 150-170 °F. To prevent flat spotting tires, do not turn steering wheel more than five times without rolling vehicle to change tire to floor contact area.
7.Check pump fluid level. Add fluid if required.
8.When engine is at normal operating temperature, the initial pressure on gauge (valve open) should be within 80-125 psi. If pressure is in excess of 200 psi., check hoses for restrictions and poppet valve for proper assembly.
9.Open and close gauge valve fully three times. Do not leave valve closed for more than five seconds as pump could be damaged internally.
10.Record highest pressures attained each time.
a.If pressures recorded are within specifications, and range of readings is within 50 psi., pump is functioning within specification.
b.If pressures recorded are constant but more than 100 psi., below minimum specification, replace flow control valve and recheck. If pressures are still low, replace rotating group in pump.
c.If pressure recorded are high, but do not repeat within 50 psi., flow control valve is sticking. Remove and clean valve. Remove any burrs using crocus cloth or fine hone. If system contains some dirt, flush system. If it is exceptionally dirty, both pump and gear must be completely disassembled, cleaned, flushed and reassembled before further use.
11.If pump checks within specifications, leave valve open and turn steering wheel to both stops. Record highest pressures and compare with maximum pump pressure recorded. If maximum pressure cannot be reached in either (or one) side of gear, gear is leaking internally and must be disassembled and repaired.
12.Turn engine Off, remove testing gauge, reconnect pressure hose, check fluid level and/or make needed repairs.
13.If problem still exists, steering and from suspension must be thoroughly examine

[Greybeard]

Just a thought...does the truck have a steering stabilizer?

[firefighter]

Just a thought...does the truck have a steering stabilizer?

This is an excellent question. Yes it does.
If you were thinking what I was thinking, one of the first things I was hoping for was a failed stabilizer so I disconnected it.
No change unfortunately.

[firefighter]

Thank you all for the updated and extra replies with suggestions.
I really appreciate you taking your time to help me.

I've got a high pressure hose and gear box on standby at our local auto parts retailer.

If I have some time, I'm going to work on it today or tomorrow.

This whole power steering stuff is pretty simple until the simple easy stuff doesn't do the trick. Now you have to dig deeper.
I'll certainly update on what I'm finding and what fixed it.

Thanks again guys !!!