power steering troubleshooting

[myotis1134]

Hey guys,

1992 MTX - rebuilt original steering rack, all new hoses, cooler and reservoir cleaned, didn't mess with the pump.

I've reassembled everything correctly, put a quart of new fluid in the system, and started the vehicle. Got a mess of bubbles returning to the reservoir, shut the engine off, and manually turned the wheels through their range of motion. Restarted the engine, and turned the steering wheel slightly. Immediately the wheel began violently jerking about an eighth of a turn right then left, until I killed the engine. I got a bloody indian-burn the first time - diving for the key.

After that I manually turned the wheels to their extremes, centered the wheel and started the engine. If I don't touch the steering wheel, nothing happens. The fluid circulates, and a few small bubbles would be pushed to the reservoir. For a little while some foam came up, then stopped. I've manually turned the wheels about 15 times at this point, but every time I put pressure on the steering wheel while the engine is running, it starts jerking to either side. The car is up on jack stands, so there's no resistance against the tires.

Tomorrow I'll crawl back under and inspect the harness and wiring to the steering rack, but I'm out of ideas. I can see how trapped air could cause things to go haywire, but how much damn air can be trapped in there? Nothing is leaking, so it's not super probable that air is being sucked in through a supply line, and besides - the reservoir level hasn't changed throughout the whole thing...

I searched the forums, but didn't find enough information to help me solve this. Any advice is appreciated.

 

[SHOMON]

Is the power steering pressure switch plugged in?

 

[myotis1134]

Yes. I'm about to inspect the wiring and connector.

 

[myotis1134]

Wiring and connector look good. The pump had no issues before I started messing with the system, and it's definitely building pressure, so It's most likely fine.
The ONLY thing that's different, configuration-wise, is the rebuilt steering rack, which probably means the rebuild was not successful - unless the brand new pressure sensor switch came defective from the factory, and is capable of causing the symptoms I described above.

Does my logic sound... logical?

 

[myotis1134]

Threw a vacuum on the system, nothing of note happened.

So when the engine is running, and I apply pressure to the wheel, the initial violent **** is opposite of the direction I first turn it. Then it does the side to side thing... If that rings any bells...

 

[blk\blk90]

So does it constantly ****, or do it once then stop? Have you tried to keep going past the violent spot? Maybe take a video and post it up.

 

[sperold]

My guess is, this is a rebuilt rack issue.
I believe that a 92 does not have the Variable Assist feature (VAPS), but I am a little fuzzy on that.

Have a look at that universal joint affair on the input shaft from the the steering wheel. They can tighten up to the point that your system senses a "spring back" to the direction you came from.
Long shot.
This issue has never been reported before, so you have to look at everything, no matter how improbable it may seem.

 

[zoomlater]

My guess is, this is a rebuilt rack issue.
I believe that a 92 does not have the Variable Assist feature (VAPS), but I am a little fuzzy on that.

Correct, 92 has the non VAPS rack

http://www.shosource.com/catalog/product_info.php?cPath=61_39&products_id=235

 

[myotis1134]

Here's a video of what happens: youtube-link

 

[blk\blk90]

Video unavailable.

 

[myotis1134]

Sorry - I don't upload to youtube, and classified the video as "private" accidentally. It should be public domain now.

Link here.

 

[blk\blk90]

Oh wow. Thats.....interesting. I'm not positive, but you may need a priest or something.

 

[myotis1134]

So I'm thinking the only component in the power steering system that is capable of causing that to happen, is a control valve in the steering rack going berserk somehow. I don't see the pump being capable of causing that, although granted - I'm not 100% clear on how the pressure sensor affects the system...

 

[BaySHO Performance]

Had that happen once. Check the jiggle valve in the pressure port. I assume you bought a reman rack rather than rebuild it yourself.

 

[myotis1134]

That's a negative BaySHO - I replaced a few gaskets on my original rack after blowing up the rebuild I ordered from Detroit Axle.
The check valve was transferred both times, but I checked and cleaned the **** out of it both times. Will it cause demonic possession if it goes bad? If it's bad, will the system function without it? If the system won't function without it, can it be purchased anymore?

 

[BaySHO Performance]

Jiggle valves don't go bad, but IIRC one went in sideways or upside down which caused the problem. If upside down, it won't open to let fluid flow. Will be OK without one I think, but best to have it in there.

On the other hand, it may be your rebuild, but I don't see how replacing a few seals would cause a problem.

Rock Auto has the AC Delco, but I had one that wasn't too good. Steering felt heavy compared with the BBB Vision I replaced it with. Best bet is probably is SHO Source. Don't know about Detroit Axle.

 

[myotis1134]

This setup is ********. Does anyone know what the thread size is on the rack and pinion hose ports? I'm going to find an in-line check valve that will thread in between the pressure hose and the rack.

 

[BaySHO Performance]

I have a rack in my garage. I'll take a look later today. But I suggest looking at the jiggle valve first.

 

[myotis1134]

So what are the odds that this is the problem?