No more power steering

[jan lauwers]

Hello folks!

I have replaced the seals in the PS pump of my 280 SL 1969. Put new oil in, changed the tubes... all fine, but it does not work!... I have no more power steering! The new oil in the reservoir stays up to the mark... there are no leaks. Wy am I not getting any steering assistance? The only thing I can think of is air in the system. I tried to vent it, but I am not sure that all the air has come out... it seemed like I could go on endlessly... then I decided to leave it and go for a test ride, because I read here that these systems at the end of the day vent themselves out. Help needed please, what am I doing wrong?

Thanks!

Jan

[rb6667]

Air in your system could indeed be the problem.  Jack up the front of car and put in on jack stands.  Start the motor and turn the wheels slowly to full lock in both directions.  Hold the steering wheel at full lock for a few seconds before you turn back the other way.  Repeat this process 10-15 times. 

If air in the system is your problem, this should work.

Keep us posted.

[Jonny B]

I did some looking with the search function, and found this from Cees Klumper

"The bleed nipple is on top of the steering box, sort of in the middle of it if I remember correctly. A parts book may have a drawing of it. It should be relatively easy to spot. I bled mine a few weeks ago and I believe it was an 11 mm nut. For the venting hose I used a piece of rubber hose that I had left over from replacing my fuel expansion tank lines, so it's "that" diamater (sorry!). If you check my post on the engine rebuild, you will see where I describe what I did, and Joe Alexander I believe commented later that bleeding the system is not really necessary as air will escape by itself.
There is a filter in the oil canister that sits on the left side of the engine, somewhat close to the distributor, with the winged nut. Only, you have to remove the slotted disk that is inside this container to see it. I replaced mine when I bled the system.

Cees Klumper in Amsterdam
'69 white 280 SL automatic"

Also a short thread where the small hose under the reservoir can become kinked and block of flow, try "power steering problems" as the search string, limiting to topics only, you should just get the one hit about the hose.

[Shvegel]

I would also try removing the filter until you have fully bled the system.

[jan lauwers]

Thanks gentlemen. I also thought that it can only be about bleeding... there is just nothing else I can think of. Good idea to remove the filter... I will try this weekend and update the forum if I learn something.

Best regards,

Jan

[alchemist]

I agree by turning the wheels to the extreme left and right several times. This procedure was recommended for most Mercedes. Good Luck.

[ja17]

Sounds like a mal-function to me. Possibly an assembly problem or dirt in the valve mechanism of the pump.

[jan lauwers]

No luck, and no power steering. I tried bleeding the system again, a lot of air bubbles came out, but it is also obvious that I have no pressure from the pump. I have no experience with this, so I can not compare, but when I turn the steering wheel with the nipple open, there is not even enough pressure to pump the content of the transparent tube on the nipple, back to the reservoir. I presume that means no pressure, right?
 
Now the big question is: what have I done wrong?
 
To recap what I have done: I had a leak in the PS pump and a leak on the steering house, but only on the bottom plate. On the house I have taken the pitman arm off, unbolted the bottom plate and replaced the seals (plus some extra Loctite sealant). On the pump: took it out, opened it, cleaned it out. (yes, also the rotor and the valves. Perhaps I should not have done that and I should have left everything where it was, but that’s water under the bridge now). I put new seals in and put the pump back together. The only moment of doubt that I had was the rotor that holds the sliding door valves. It can go in the pump house in 2 ways…I had some doubt and put a quesiton here on the forum, because I could not remember which way it had been sitting in the pumphouse. My question is here: Topic: ‘putting power steering pump back together’, january 13th.
http://www.sl113.org/forums/index.php?topic=19866.msg140173#msg140173

Does anybody here have detailed enough knowledge of the pump to understand why I am not getting any pressure?

Lastly: I have no twisted or bended tubes….

I am desperate for help!

Thanks a lot guys.

Jan

[ctaylor738]

I looked at your other post, and also at the 107 CD which has instructions on assembly of the Vickers pump.  From the picture on page 7 (Vickers VT49) pump, I would say that the cone side goes under the locking ring.  But I can't see how that would make any difference in the pumping action, which comes from the little blades turning in the pressure plate.

Attaching the relevant sections.

Best of luck,

CT

[andyburns]

Jan,

If your desperate have you ever considered trying to source a second pump.  They are cheap enough second hand and by process of elimination you could very quickly isolate the problem.  Changing the pump over should only take an hour or so.  The pump is common to the W108 so should be reasonably easy to come by and cheap.    If you lived a bit closer you could borrow one of my spare ones.

[ja17]

Did you get the key back on the shaft to connect the pulley? If left off the pulley might just spin without turning the pump shaft.  Easy to check, the pulley would be turning and the nut would be stationary.  I still think it might be something caught in the check valve of the pump.

[alchemist]

Most Mercedes through the 1970's use the same type of pump. You may hunt for a used pump from a junk yard not necessarily from SL car. It can be from 230, 250 or 280.

[jan lauwers]

Thanks a lot gentlemen for these useful replies.

Seeking for evidence of pump pressure this weekend, I slowly released the nut that holds the high pressure tube on the steering house, while the engine was running. My assumption here was that, if the pump was giving pressure, it would be obvious by ATF spraying out as soon as I would loosen the nut. Well, that was not really the case... it was more like some dripping that started when the nut was coming loose, nothing like a spray of ATF!. So, that makes me think that I have no pressure from the pump... does this make sense?

The grey MB book shows a trouble shooting table. For ‘no pressure’ it states as most likely cause: a stuck volume control valve. When I took my pump apart, I have not removed this valve. If I do the job again, would you recommend that I take this valve out and clean it, or is there a risk that I deregulate this valve?  I am more and more convinced now that I have made a mistake somewhere in the assembly of the pump.

What are the recommendations for finding the right poulie puller for this job? Is there a fixed type of a given brand that fits this job? I used what I could find as a puller and I ruined my poulie…(put a new one in) . Don`t want to do that again!!!

PS: a big thank you to Andy for his generous offer… I`d happily come to New Zealand to borrow your pump… it is only on the other side of the globe and that is one of the reasons why this forum is so fascinating. Also thank you to C Taylor. These drawings are VERY useful. Which MB book are these from?

thanks again for all your help guys and have fun!

Jan
Geel, Belgium

[ctaylor738]

They came from the 107 CD from Mercedes for a 1972 350SL.  They are also in the 123 chassis manual.

[jan lauwers]

Hi Chuck,

You're my hero!

This weekend I did the work over again, and opened the pump for the second time. I compared what I saw with the drawings that you sent over and suddenly I saw the mistake that I had made: I had the cam ring (part 6 in the drawing) sitting upside down. As a consequence the oil outlet channel was almost completely closed off!
Tonight I filled up again, bled the system and YES, power steering. I am so grateful for your help!
This forum is great. I also used your posting about removal of the pump with the bracket all together. I will make one additional comment in that threat, to hopefully make it even more useful to other members.

Thanks again and all the best,

Jan