Unknown power steering reservoir (no part number) - 1997 SL500

[Xanzar21]

I'll keep this brief I can't for the life of me after four hours of searching find the specific reservoir for this pump; at this point I'm assuming its year specific and sold as an assembly. That said I would like to "upgrade" to an aftermarket unit as this reservoir is currently MIA. I only need to worry about the return and feed line sizes; probably going to use a mishimoto unit. In case anyone was wondering the reason I'm looking for a reservoir is because I forgot to disconnect the return line before doing the engine mounts. Any help would be greatly appreciated. pictures of the reservoir and assembly in question are attached. The car inquestion is a production year 1997 r129 sl500; thought I'd ask here as quite a few parts are shared and someone here has probably had to do the same since the 90s right? right?

 

[TerryA]

Are you sure the part on the car is an original OE MB pump? I think it should have an MB stamp and part number?

 

[Markus-MD]

Looks like an Normal late Steeringpump.w210 has the same om the 985 Engines.

 

[Xanzar21]

OK did some more digging, it looks like the powersteering pump reservoir mounting holes are the same as the earlier zf pumps. So I ordered one off ebay. It should arrive Tuesday 06/02/2026. Its a gamble but it might pay off!

 

[Xanzar21]

Are you sure the part on the car is an original OE MB pump? I think it should have an MB stamp and part number?

The pump itself is fine and an original mb/zf unit, its the reservoir that doesn't have much information online. There's a post on benzworld that has some of the ZF partnumber visible, the image quality leaves much to be desired. The late w210 has the return line routed in the wrong direction and there doesn't appear to be much room to use it on this .982 setup in the r129. I'll post images and update you guys on how successful i am next week !

 

[Xanzar21]

got the part number for the reservoir after hacking it apart not my best work but here it is : 7691 462 120 . for added information I will also attach the pump parts number: (ZF) 7682 900 511, (mercedes) A 129 466 23 01 it also has a bar rating of 115. photos below. The new(old design) pump should arrive tomorrow 06/04/2026. I will update with info on whether or not this worked as well as part numbers for its respective pieces. Hopefully this info will help someone in the future.

 

[Xanzar21]

OK so an update, the bolt pattern on the 95-97 direct mount reservoir works. However there isn't enough clearance to install it directly on a m119.982 (it might work differently on an earlier m119 with the direct mount). That said i will have to source the remote bracket and reservoir from an earlier model( the one thats famous for leaking from the miniature hose connecting the reservoir to the pump) . I'm in the hole $100 , but thats $100+ someone else won't have to spend later. Anyway i'll post pictures later on Sunday. Went on holiday.

 

[Xanzar21]

Forgot some details, its crucial to note that the reason it will not work is that there isn't enough clearance between the reservoir and the head. That is to say the reservoir will not fit even with the metallic return line equipped. I should also add that I was able to source the reservoir mounting bracket and its required hardline alongside the even older reservoir and requisite filter. Its crazy that this power steering reservoir had a filter and the later model plastic reservoir doesn't.

 

[Xanzar21]

A brief update: old bracket and old pump are inbound and should arrive by the end of the week. Which means I have access to all three versions of the ZF pump and reservoir setups. Does anyone need specific part numbers?

 

[Xanzar21]

its arrived, will be installing it on my car soon
here are the pictures as promised. Note that the top left allen key bolt that secures the bracket to the engine does not line up on the m119.982; i'll have to find a solution for that ; the other bolts do so its not so bad. juding by the fact that the middle pump has a 110 bar rating; i can only assume that what governs the pressure is the seals the pumps are fitted with. This is only a theory that I have no reason to test(don't know how bad it could end and not taking the chance), but I'm pretty sure you can build a pump "body" from 110 all the way to 125 bar. Provided you repack it with the right seals. all of the pumps have the same internal and external feed bolt patterns ; even the flywheel is the same. So we should probably get into producing aftermarket "tophats"(the metal that interfaces with the reservoir) as $700 for a repacked pump is obscene, if all you need is the top hat to convert the pump for use elsewhere. Again it should be noted that the original pump fitted to my r129s m119.982 has the plastic reservoir and that unit does not have a filter; the other ones do.

 

[Xanzar21]

ok I stand extremely incorrect; I was just being stupid; all mounting bolts for the bracket work. the r129s original return line is too short to aptly supply the pump with fluid, mine is kinked in two areas. the original supply line to the rack is slightly too short; you can get it to fit(my arms hurt , it was not easy to install) but it would be easier to simply replace it with new old stock(rockauto, its my jam). So moving forward we as m119 owners are faced with a question: Do we create a company that rebuilds and repairs engine components and accessories, or do we do limited run group buys? Right now as it stands there is no readily available literature about what would or wouldn't work regarding these pumps(as far as I know there's nothing about the luftkraft units either) . In summary : I GOT EXTREMELY LUCKY, this likely won't happen again. Parts availability is becoming a problem in general.

 

[Xanzar21]

Another update, don't be me; read the workshop book. Forgot to jack the front wheels up and bleed the system of air. Started the r129, it sounded like someone firing a machine gun; took everything apart rebuilt both 115bar pumps. finally realize that it was probably air trapped in the system. Reinstalled the system; read the workshop book. Take this as a cautionary tale; remember to lift the front of the car on level ground so that the wheels do not touch the ground and rotate the steering wheel with the engine off 30 times to bleed the power steering system of air. The pumps will function without the bleed, but it will hurt your ears the entire time. Thanks for your patience.