Author Topic: Power steering pump belt tension bolt  (Read 1146 times)

ryan.mb

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Power steering pump belt tension bolt
« on: September 17, 2024, 17:23:37 »
Hello all,

I bought my Pagoda a while ago and I’m working on its restoration. I’m working on power steering pump assembly and some parts are missing.

It looks like that M10 bolt on which power steering tensioner (loop) is fixed should have smaller diameter at the end and without thread. Also it seems that there should be something else at the end to fix power steering tensioner bolt.

Does anyone has pictures of this part of assembly (marked with red in schematic) or some records of how power steering belt tension bolt is fixed/mounted/secured?

Cheers,
Ryan
Ryan
1967 W113 250SL
1984 R107 500SL
1990 R129 500SL

BobH

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« Last Edit: September 17, 2024, 18:29:02 by BobH »
February 1965 230SL Automatic
UK delivered RHD
Papyrus white, blue hard top & hub caps
Blue soft top
Blue leather

Pawel66

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Re: Power steering pump belt tension bolt
« Reply #2 on: September 19, 2024, 07:40:10 »
I think you will find what you need on the attachment.

Your first question: yes, it is a special bolt.
Your second question: there is a nut and a counter nut.

Yellow dots indicate availability at Mercedes dealers, 72hours (here). I covered prices not to breach anything, I can only tell that the bolt is obscenely expensive and the clamping bolt is horrifyingly expensive.

Please also note that the bushings (48) are also available if need be. They are quite important, I think.
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

VikDasor

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Re: Power steering pump belt tension bolt
« Reply #3 on: September 19, 2024, 20:55:04 »
Hi Ryan

Is this what you are looking for. Ignore the big nut and the spring washer as that is for the pulley.
Vik Dasor
1966 W113 230SL
1988 R107 300SL
1999 R129 320SL
Porsche 911 997 C4S

ryan.mb

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Re: Power steering pump belt tension bolt
« Reply #4 on: September 29, 2024, 18:18:44 »
Thank you very much for your input and time BobH, Pawel66 and VikDasor. Here is summary of my research. This is all very interesting, and it looks like there are two engineering solutions for this assembly because there are different steering pumps - one with thread in the housing and the other without thread in the pump housing.  I’m talking about Bolt No 45 in schematic shared by Pawell66. Clamping bolt No 43 in the same schematic and also picture shared by VikDasor is the same in all cases and it is all clear about it.

1. In the manual BobH shared which is from 230SL there is schematic (please see picture attached) steering pump does not have thread in the housing and hence there is Hex-head screw (22), then washer (23), then another washer (23), then tightening screw (clamping bolt) (24), then locking plate (26) (part No A1274660073) and then hex nut (27). This is also corresponds to schematic I found on W110 (please see picture attached). My concern was that when you tighten the tightening screw then the clamp damages thread of Hex-head screw No22/No634, which would be an issue if steering pump would have threaded housing, because when you would screw it out the damaged thread would also damage the thread in the pump housing.

2. In the schematic Pawel66 shared there is just the Bolt (45) and washer (39) (there isn’t any locking plate and hex nut). This is intended for steering pumps with thread in the pump’s housing. Which is what I have. Bolt 45 (part No A1279900101) has no thread at the end and end is in smaller diameter. The clamping bolt 43 is mounted on no thread part of Bolt 45. In such case it does not damage the thread and resolve above mentioned issue. But the question remains how clamping bolt 43 is secured on the Bolt 45, does it remain there (does not slip off) just by tightened force, meaning there is nothing at the end of Bolt 45?
Ryan
1967 W113 250SL
1984 R107 500SL
1990 R129 500SL

Jordan

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Re: Power steering pump belt tension bolt
« Reply #5 on: September 29, 2024, 19:18:21 »
Ryan, bolt 45 goes through the hole in the tightening screw (bolt 43).  If your steering pump is threaded, then I would expect that you then screw bolt 45 into the pump.  So it would be impossible for the tightening screw to come off bolt 45.   Does the threaded hole for bolt 45 in the pump go all the way through?  Mine is a late 230SL and it is set up as per BobH's illustration (pic below).  When you tighten the hex bolts on the tightening screw it pulls the entire pump, thereby tightening the pully.  The hole through which bolt 45 passes in the bracket is slotted so it moves horizontally with the pump so it would not damage the threads on bolt 45.  Hopefully I am explaining this correctly.

Still waiting on parts before I pull my pump.

Marcus
66 230SL  Euro 4 speed