The w115 200D that I'm restoring will be out from the body shop soon and I'm planning to convert it to power steering. I've read somewhere that the w123's power steering box and pumps are interchangeable with the w115.

I'm not very sure about the steering shaft though. I think I will need a shorter one to fit the power steering box, will a w123 shaft work?

I don't believe that this whole exercise is really adviseable. The W115 220D noted below was my daily driver in city traffic, including parallel parking, on the interstates, and over rural roads for nearly 20 years. Never once did I ever find it necessary or wish for power steering. If the front end is set up correctly it is a great handling car.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

if you do decide to add PS, consider an electric pump (used in newer vehicles) which will save you the trouble of mounting a pulley-driven pump.

PS, if this conversion is practical, then perhaps the 115 is a source of manual steering boxes for W123 owners that like to avoid the pump! (greazzer....)

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'77 240D, 504H, OM617.952, etc.

I appreciate your inputs but some w115's actually came out with PS, only I can't source a complete system from where I live.

W115 pumps are not the same as W123 pumps. The W115 uses a pump mounted low on the block opposite the alternator. It has a remote reservoir. If you use the W123 pump interference with the battery becomes a problem. You would also need the W123 drive pulleys etc.

W115 manual boxes will not fit the W123. If they did I'd be happy as could be. As has been said the W115 with manual steering handles well, is easy to park and has excellent feel. For me power steering is the first thing to go.

On the other hand driving a manual steering car takes more effort and the ratio is slower. When I pound through the twisties I can work pretty hard. My wife doesn't like manual steering and if I were driving in the city a lot I'd probably convert to power.

The W114/115 is known for cracking around the steering box mounting area when equipped with power steering. The area can be reinforced. I recall reading about a factory repair plate. If not I've seen a few home brew plates that worked well. If you convert use new correct bolts, properly torqued and keep an eye on it. Check the torque regularly.

I like the idea of an electric pump. A 200D will need all the help it can get. Another idea I've toyed with is an electric assist column. Many newer cars use them in conjunction with a manual rack. It would be hard to implement but all the hydraulics could be eliminated.

The easiest way to do this will be to find a power steering equipped W115 and pull everything. This includes the steering column. Cars with manual steering have a longer steering shaft. You will need the steering box and pitman arm too. The manual steering arm has a different spline. There are some gotchas too. One that comes to mind is a drilling in the upper oil pan that is only present on engines originally equipped with power steering. That hole is essential for the pump bracket. There are some additional items involving the engine stop bracket and another support stud near the vacuum pump. Any missing support on a diesel will result in a cracked bracket.

Good luck!

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1969 220D 5 Speed (OM616)
1983 240D 4 Speed
1985 300D Auto 376K
1985 300D Auto 275K

Your desire to add weight and complexity to your car makes no sense to me.

There goes my reason for clicking on this thread. At least I know now.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

Well, that is why you did not start a thread like I did. In this case, it doesn't matter what makes sense to you, because this thread is not about you or what you want to do to your car.

I raised a question about parts compatibility and it wasn't a question of whether or not is it a good idea. Also, there are w115's that had power steering from the factory so it's not at all unreasonable to want one.

I need the power steering so a female can drive my car without exerting too much effort when parking it.

Hi!

Here is original DB's guide for aftermarket installing of the PS.
http://www.roststopp.de/strichacht/daten/MB-SA-Servolenkung-LS90-1973.pdf

Thanks for the link. Though I will have to translate 10 pages of German.