Please Help - Power Steering Pump and Pulley Mystery

[BarryD]

Several weeks ago I heard a bad sound from the front of my engine, but was relieved to find that the nut securing the pulley to the power steering pump had come loose, and the noise was from the wobbling pulley. I then found two problems: 1) the pulley wobbles slightly on the pump shaft, and 2) when I tighten the nut, the pulley binds against the adjuster screw on the face of the pump bracket. It also seems to be rubbing on the pump body right at the shaft.  Examination of the pulley and shaft show that there is nothing to keep the pulley from binding when the nut is tightened. Something is incorrect, but I don't know if it's the pulley, the pump, or I've attached a sketch to show what's happening. I also took photos of the pump shaft and pulley.

A bit more information: 1) Neither the shaft nor the pulley are tapered. 2) The car is a late model 250-SL #4542. 3) The pump is a Vickers Model # VT-27-100-50-85-19 10MGE66.

If anyone recognizes an incorrect pulley, incorrect pump, or any cockpit error on my part, please let me know. I'm really confused by this one.

Thanks, Barry

[Paul & Dolly]

Hi Barry,

You do not say if the Woodruff Key is in place or not ?

Paul

[UJJ]

I think that the pump with the straight shaft should have a shoulder for the pulley to rest against.
Is it possible that yours is worn away?

[BarryD]

The Woodruff key is installed. Regarding a shoulder on the pulley, I don't see anything on the shaft that the shoulder could rest against. If the pulleyis supposed to have a shoulder then perhaps my pump shaft is incorrect or damaged.

[Paul & Dolly]

Hi Barry,

This is all I can find,
not much help I'm afraid,

Hopefully a more knowledgeable member will answer
Good luck
Paul

[ctaylor738]

As part of the restoration of my 280SL, I got a rebuilt straight shaft pump from C&M Hydraulics.  I had this exact same problem.  They told me that there is supposed to be a washer that goes on the inside of the pulley that moves it out far enough to clear the bolt head and prevents the inside of the pulley from rubbing on the pump.  Unfortunately, I could not find this washer - its size has to be just right.  If it's too large, then it will rub and grind itself away.

I ended up installing a tapered shaft pump and pulley.

[BarryD]

Thanks for the reply Chuck. I made another sketch showing what I understand from your comments. I showed a shaft with a shoulder that would keep the washer you mention from grinding against the pump body. The pulley presses on the washer and therefore doesn't grind on the pump body. The picture of my pump shaft (above) is straight - it has no shoulder. Perhaps it got ground off at some point when someone installed the pulley without a key??

If someone can tell me that the straight-shaft pump is supposed to have a shoulder on the shaft, then the mystery is solved!

[ctaylor738]

Well, what the guys from C&M seemed to be saying was that the washer was sized so that it would clear the pump housing and not grind itself away.

[BarryD]

I spoke with Chris from C and M Hydraulics today. After speaking with him it's pretty clear that my pump shaft and pulley are both damaged. He told me that the straight shaft units are very difficult to find, so he recommended I buy a tapered-shaft pump and pulley. I told him that a picture of the straight-shaft pump may help others on the site, and he graciously obliged. The first picture (black pump) shows the pump with the oil seal intact. The second picture (silver pump) shows the seal removed.

[ctaylor738]

From memory, the picture with the seal looks exactly like my pump, with almost no shoulder.  I think it needs the magic washer/bushing/collar to make it work. I'm traveling for a couple of weeks, but I will chase this some more when I get back home.  I'd like to sell my almost unused straight-shaft pump.

[UJJ]

You need to have a spacer which rests against the shoulder and is smaller in diameter than the ID of the radial seal.

[ctaylor738]

Exactly.  But I could not find a PN for it.  Any idea?