DeWolf

Is there a special trick to get all the air out of the power steer system?

Cheers
Scott

jpitman2

Jack up the front wheels, move the wheels back and forth lock to lock, top up as needed. You will also get groaning if there is anything obstructing supply to the pump, like the hose delaminated inside, or collapsing.
jp 83 Euro S AT 57k

danlboon

FredR

No harm in trying as JP suggests but I doubt jacking it up it will make any difference as the PS pump is easily flooded. When I did mine I started the motor and instinctively turned the steering lock to lock a few times.

Doubtless you understand the need to change out these hoses. I had my high pressure hose rebuilt in a local hydraulic shop and made some low pressure hoses myself. If you do not know how old the current hoses are chances are they need replacing. Just another of those "sooner or later" items! Check the hose from the reservoir to the pump to ensure there are no obvious kinks in it

jpitman2

The jacking up was just to reduce the loads on the steering gear, not to affect the pump or fluid. There is a restrictor on the hose externally, where it crosses the inner fender, I dont think there is an internal valve. I had my hoses rebuilt locally, and later found they were not much cheaper than genuine items, so I am surprised to hear they are considered costly RHD hoses are longer also. Dont forget that a pinhole in the pressure hose as it goes past the exhaust can cost you the whole car.
jp 83 Euro S AT 57k

FredR

JP,

The bit about the restrictor is something of a myth on the later models at least. There is a metal collar in the middle but it is nothing more than a lightly crimped cover over the top of the hose presumably for the support rubber cushion. Whether there is a restrictor in earlier model hoses I cannot comment but for sure there was none in mine. Cost me something like US$15 to get mine rebuilt in a hydraulic specialist shop I know and trust. I know there are concerns about this approach in some quarters - all I can say is it has worked for me to date and the cost was way less than a new item. Either way running around with a high pressure hose of unknown provenance is a potential 928 killer just like the fuel hoses.

DeWolf

Yeh Thanks guys. I just spent this evening stripping out all the steer lines. I am going to have them rebuilt here at Enzed. They do all my other lines and no troubles ever. I don't how much pressure goes through the high pressure hose but they ( Enzed) guarantee 6000psi no problems. The same mob do all my sons hydraulic lines on his skip bin truck.
JP is correct about a restrictor in early cars. The hose has a piece removed and a smaller diameter metal section, maybe 100mm long, crimped between them.

SeanR

jpitman2

Fred - $15 maybe an Oman price, it isnt that cheap in a western country. I used to get prices like that in Riyadh - thats where I had my 3 piece S front spoiler welded back together for peanuts.
Scott - thanks for clearing up the restrictor part - mine just has the external part on it. I had my hoses built at a Ryco agent in Melbourne, cos I worked at Ryco then. Only problem is they are an ugly blue hose.
These pumps are VERY fussy about input supply - my Subaru pump gets noisy when the fine O-ring (1mm section) on the input fitting gets hard and tired.
jp 83 Euro S AT 57k

hacker-pschorr

+1
The non-pressure hoses can actually leak inward sucking in air and never show a drop outside. While I've never had this happen with a 928, our Saab and one VW experienced this. Replaced the non-pressure hose, the noise went away.

When I did my TB/WP in my 87 I replaced the reservoir and the non-pressure hoses. After much fiddling and driving the noise was still randomly there, especially on a cold morning.
Desperate for a solution I sucked out some fluid and dumped in a bottle of Royal Purple power steering sauce. Wheel back & forth multiple times & went for a drive. I haven't heard a peep since.
Could be coincidence, but I put on close to 1,000 miles before trying it.

Simon928

I had a similar experience to what Sean described. After buttoning everything back up after some Power Steering work I would get a groan from the pump that I couldn't get rid of. It ended up that one of the bolts on the power steering pump wasn't tightened enough, and once I torqued it down the groan went away.

FredR

When the hoses get old one can pinch them to test how "rubbery" they are. If they feel a bit "soggy" there is a good chance they will partially collapse or even kink and at some degree of suction blockage the pump will cavitate - not a good thing! Also quite conceivable that they get cracked such that air gets sucked in when the pum is running and yet nothing leaks out when the motor is not running. If my example was anything to go by once one sees signs of ATF around those hoses time to replace the job lot.

At least it is good to know that I can get some things done cheaper over here to offset the airfreight and modest import duty [5%] of bits and pieces from halfway round the world.

Captain_Slow

This is a great thread. I've never heard of the collapsing hoses, air leaking inward through old low pressure hoses, or the leaking bolts on the pump.

Will groaning happen if the built-in-filter in the reservoir is blocked with sediment? How often does this really happen (anyone cut open a reservoir to inspect filter)? Perhaps the above causes are creating the groaning while assuming it is a clogged filter starving the pump. If air is leaking in anywhere in the system will it make the fluid look foamy or bubbly in the reservoir?

soontobered84

I replaced my Reservoir on the Stepson to get rid of my steering groan. Apparently the internal non-replaceable reservoir filter was just clogged enough to limit the amount of fluid to the pump and induce the groan.
Called Roger for the replacement and groan was gone.

There IS a restrictor on the PS hose underneath that rubber cushion/bumper. It was supposed to minimize the groan somehow, but I have had several PS hoses rebuilt locally and never replaced that restrictor and it's never seemed to make a difference. No groan before and no groan after.

Hey_Allen

I don't have any direct 928 power steering suggestions, but I had plenty of fun with older MB cars and their power steering pumps.
The obvious one that would cause it to talk was if it got low (in my car's case, it was slinging off the back of the pulley, due to a leaky shaft seal). Once that was fixed, that car quit groaning.

The other car I never found the root cause, and it did it infrequently, but it did go away when I added a pint of LubeGard power steering protectant. Not something that I'd normally consider, but after a fleet mechanic family member suggested their ATF additives and I had good luck with them in the MB, I gave it a try for power steering.


Regarding the restriction in the hose, it's interesting how the different makes work at quieting down the hydraulic noise in the power steering system.
MB's solution in the 70's and 80's cars was a set of little funnel shaped baskets that were fed into the hose and secured in the line by the swaged on fittings.