Power Steering

1965 - 1972: 250S, 250SE, 300SEb, 280S, 280SE, 280SEL, 280SE 3.5, 280SEL 3.5, 280SE 4.5, 280SEL 4.5, 300SEL, 300SEL 6.3, 300SEL 3.5, 300SEL 4.5
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W108-1967 250S
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Power Steering

Post by W108-1967 250S » Sat 23 Oct, 2010 5:22 pm

Has anyone overhauled a early power steering box? ('67 250S)?

Situation so far-Going to a mate who runs a hydraulic shop to possibly have a new pressure delivery rubber hose made up as the Benz one will probably be $$$$$$$$$$$$$ ? The steering was working fine and was making no noises as I recall but had the usual bottom seal leak, evidence from hyd oil spill in that area when prepping the engine bay for re-spray. An engineering shop took the pump apart and cleaned it up and replaced O rings. I was told it's a fairly basic vane type pump. Made by "Vickers", wonder if that was the Vickers of Wellington/Valiant bomber fame? So thats all painted up and ready to go back in the car. It's a bit unusual in that the resevoir is bolted directly to the top of the pump. Most I've seen are mounted a bit higher up with hyd' oil supply pipes to the pump. Havent yet replaced that strange little filter yet, what is that made of? Very brittle I understand, so handle with care.

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Phil T
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Re: Power Steering

Post by Phil T » Tue 26 Oct, 2010 11:25 am

Hi

I had new power steering hoses made up by Pirtek. No problem. The guy doing the job knew about power steering hoses and the small flow restricter in one of the hoses.

When you refill the hydraulic system with oil, you can't just fill the reservoir once and start the engine to pump the fluid through the system. You need to fill the reservoir and crank the engine without starting it and keep topping up the fluid in the reservoir as it gets pushed down through the hoses and the steering box. Don't let the reservoir run empty during this process. Only then start the engine when the whole system is filled and the level in the reservoir remains constant.

Phil T

W108-1967 250S
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Re: Power Steering

Post by W108-1967 250S » Wed 27 Oct, 2010 11:07 pm

PhilT
Thanks for that. Who are Pirtek? Do they have branches in Brisbane/Canberra? Thanks for the starting it up again tip. I understand you can bleed the system (change fluid) by opening a bleed nipple on the steering box, dumping that fluid overboard, and keeping the resevoir topped up? Did Pirtek say anything about re-newing seals on the steering box?

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Phil T
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Re: Power Steering

Post by Phil T » Wed 27 Oct, 2010 11:32 pm

Hi

Pirtek is a hydraulics franchise Australia wide. The make up hydraulic hoses to suit anything. Do a google search and you will find one not far away. Same as Enzed. You could also try them.

I doubt they will be interested in your pump. But maybe they will. Depends on the guy who runs the business. A local power steering repairer would be a better bet. There is nothing particularly fancy about the power steering pump. Not even made by Benz. Just a bought in item from Vickers.

Phil T

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drew56cus
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Re: Power Steering

Post by drew56cus » Thu 28 Oct, 2010 7:45 am

Hi 250S. Bleeding the P/S is easy. I don't necessarily agree with Phil about not having the engine running though. We just connected a suitably sized hose (I just bought some clear tube from a hardware store) from the bleeder on top of the box around to the reservoir, and ran the motor. Then open the bleed screw and slowly turn the wheel left and right a few times until no more air comes through. Close the bleed nipple and you are done.
Cheers, Drew
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Phil T
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Re: Power Steering

Post by Phil T » Thu 28 Oct, 2010 12:35 pm

Hi Drew

My comment about not starting the motor was based on my own experience when I filled the reservoir for the first time after the long rebuild and everything was completely empty of fluid. When I started the motor, all the oil in the reservoir was immediately pumped into the hoses and with an empty reservoir, the pump pumps air into the system and the whole lot truns into foamed oil. My suggestion was about the first fill of oil after a total rebuild. As long as the reservoir does not run empty, then your bleed process is good.

W108-1967 250S
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Re: Power Steering

Post by W108-1967 250S » Thu 28 Oct, 2010 7:43 pm

PhilT & Drew,

Thanks. I know ENZED, will give them a call, My pump is OK, I had an engineering works mate I know look it over and he replaced O rings and said it looks OK, simple vane type pump. It's the steering box itself that I would like seals replaced on. The system was working OK before stripping (check out my "car pics" post) but the steering box seems to have a leak in the botton steering arm output shaft. A mate runs a hudraulic shop here in Toowoomba and plan to have the pressure hose re-conditioned by him.

W108-1967 250S
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Re: Power Steering

Post by W108-1967 250S » Sat 04 Dec, 2010 11:43 pm

Further to this topic, I have bought a complete gasket set for the power steering box. Howeve,r may leave it till I get to Canberra. Would like to strip the box to replace gaskets and check for wear. Anyone have any literature on this? for example if you remove the steering arm off the output splined shaft, do you need to mark it to get it back on in the right position. I should imagine if you don't, you may end up with a 1/4 turn to lock one way with 2 1/2 turns the other way! The exploded diagrams in my spares manual, :think: suggest this is a complex piece of kit!

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Re: Power Steering

Post by John Green » Sun 05 Dec, 2010 8:48 am

There are quite a few special tools to do the reseal on thoses boxes, best left to someone who has them as failure somewhere around a roundabout of the shopping center carpark is not a good option.

Filter is still available as a part (in stock) and if it has gone brittle is way past the use by date. A small junk going into the pump would be a bad move.
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Mercmad
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Re: Power Steering

Post by Mercmad » Sun 05 Dec, 2010 8:19 pm

I agree with the above about special tools for the steering box rebuild but with one caveat ,the only part that needs expertise is the 'gut pack' in the box. That is the part that contains all the balls on the worm. It needs special guages to set the initial pressure . The only seals you need worry about are the lower pitman shaft bearing and steering input shaft seal.
As a matter interest I was talking with a mercedes mechanic last month about these steering boxes and he said in 35 years he has never rebuilt one,only replaced the two seals. These are tough unit unlike the later W126 units which are chronic leakers .
:)

regarding your hoses,insist that the hoses have crimped ends,not those push on fittings so beloved of the hose franchise people. Only one hose has pressure,the smaller one . You will need to bleed your steering box,they all do after being emptied. As Drew said above ,you connect a hose to the nipple on the steering box,stick it into the reservoir and while the engine is idling run it until the reservoir has clear red fluid with no bubbles or foam,and always check the level with the engine idling.

W108-1967 250S
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Location: Tamworth NSW

Re: Power Steering

Post by W108-1967 250S » Fri 24 Dec, 2010 12:58 am

Mercmad, thanks, have read about bleeding the system using the bleed nipple on the steering box and dumping that overboard into a container, whilst topping up the res'. I suspected the "gut pack" might not need attention but I have come across many that leak at the splined pitman output shaft seal. Will need to put the box back in the car so it is steerable for move to Canberra. I assume no damage can be done by steering car with no pressure in the system? It won't be full, but there should still be quite a bit of oil in there. Actually thought of installing a manual steering box that I have, but will go the extra yards with the power system due originality.

Mook1
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Re: Power Steering

Post by Mook1 » Sun 13 May, 2018 6:40 pm

Just to add to this thread having pulled one of these apart;

You can make the special measuring tool yourself. A wood batten with a centre hole that can be tapped on to the spline and so pivots on the spline. Adding weights at centimetre increments (I used nuts with nylon string) you can dial in the light forces required. There is a W126 forum thread explaining this measuring in detail, see link below.

http://www.peachparts.com/shopforum/die ... g-box.html

The Oldtimer website had a great article on rebuilding the unit though is now defunct. Pagoda forum also has some nice articles.

The unit is not too difficult to pull down, clean and put together with new seals and adjust.
1971 300SEL W109 3.5L
1993 E320 W124 3.2L

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