Have 2 High Mileage 450 SE's, one a 74, the other a 75.
Both run well, but both have excessive pwr steering leakage.
I haven't investigated much yet as to where it leaks, but
I have to fill the whole canister once a wk. on both cars.
Power Steering fluid is relatively cheap, but am I doing damage
to the pwr steering pump or steering gear when it is DRY?
Also, what is the most common source of leakage (have no Obvious
hose problems, but haven't looked under the cars yet.)
One of them almost looked like it was leaking out of the top of the canister.
Could the fluid be heating up and doing this?

hey,

you should investigate the leak. If your engine bay is dirty then just look at the clean spot to find the leak. My 450sel has a slow leak at the return hose end but i have to fill in a very little every 2 weeks or so. I dont worry about it all that much but keep an eye on it to make sure the level doesnt get too low. I would recommend that you never run the car without power steering fluid in it because that will kill your car and not only is it expensive but it also makes my ears bleed.

Peter

I would guess most common is the low pressure return hose (easy, cheap fix) or the steering box gaskets (not so easy/cheapp fix).
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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The hoses get old and fluid actually leaks through them. The front seal on the pump is also a prime suspect.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Thanks for the replies.
Another thing I have noticed is that when I took the cover off
of one canister after a little driving (not long, severe, or hot)
the fluid (down a little) was frothing, bubbling like it was getting heated.
Nothing has been changed from stock.
Could it actually be overflowing out the top of the canister?

My friend's '72 280SE 4.5 did that. I think it still does. Have you tried flushing it and replacing the P/S filter?
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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if the system gets air in it it will prolly do that, it has to bleed the air out

mine (a 71) leaks from the reserviour if its not really tight. i kept cleaning the sealing surfaces and it kept seeping out of there until i tightened it more

The little pancake PS fluid filter sits in the bottom of the reservoir. Most people dont even know it's there. Costs about $4 for replacement.

And the approved method of draining the system is to disconnect the return line from the steering box and crank the engine to empty the fluid, I kid you not.

Using official MB power steering fuid instead of ATF might help. There are nylon seals and parts in the steering box. Flushing the system and installing a new filter is the first thing I would do. Creamy discoloration and foam might indicate water in the system.

You have a leak and you are getting air into your sysyem. Does your system ever howl, especially at low speeds and turning sharply. If so then you probably have a leak on the low pressure side. Go to the car wash and blast the hoses and box etc. with soapy water and then rinse.. Drive it about 15 minutes and then lay cardboard on the driveway and place your car on the card board and let it run for 15 minutes and then look to see what area the leak/s are coming from. Changing your filter(John's idea) is a good idea and easy to do.. Please let us know what you find....I discount water because you have been replacing your fluid so fast that it can't be water...Jim

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James A. Harris

Jim- your reply is right on. It does howl, and has gotten low at times that
there is undoubtably air in the system.
There are two hoses that go into the canister.
Which one is the low pressure one, the one more towards the
front or toward the rear?
It still looks like it is seeping out of the top when it is "frothing"
Could the top gasket be bad enough to allow this, or is this
because air is forcing it out?

The low pressure will be a hose with just a clamp holding it on. The high side will have a machined fitting on it that has to be unbolted to be removed from the pump.
Thanks
David

P.S.
Off memory, I THINK low side is the higher hose. It's easy and cheap to replace. HOwever, you need to order the hose from Fastlane so you get the wider stuff. Autozone, etc. don't have P/S hose that wide. Normal cars have a thinner hose, I tried already.
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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I would venture your box is leaking. MB never had many problems with leaking boxes until they came out with the V/8 around 1970. That exhaust manifold is right next to the box with no shields. The heat takes its toll on the seals.

Peter

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Auto Zentral Ltd.