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Registered
1987 560SL (L.Tonk) [92,700 miles]
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320 Posts
Discussion Starter #1
My 560 was making some awful groaning and moaning noises whenever I turned the steering wheel for the first 30 minutes of driving, before disappearing. Intuition (and some searching) pointed to low power steering fluid level.

Amazingly, it took me an incredibly long time to search for the info on how to rectify that! So, I humbly aggregate that research here so other noobs can hopefully find it more quickly. If I've made any mistakes, please let me know.

This is your engine:


Look bottom right for the reservoir:


Unscrew the nut remove the cover and fill'er up. Look for the fill line on the inside of the reservoir, about 1cm from the top.


Use actual power steering fluid. The real MB stuff is only a few bucks but many folks have used other brands without issue. In the past, you could use automatic transmission fluid as it was basically the same thing, but ATF now has additives that are not appropriate for the steering system.

The fluid level will rise when the engine is hot so don't overfill!
 

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Outstanding Contributor , Bob's Your Uncle!
-----'83 280 SL----- 5 speed....The PIG
Joined
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29,512 Posts
My 560 was making some awful groaning and moaning noises whenever I turned the steering wheel for the first 30 minutes of driving, before disappearing. Intuition (and some searching) pointed to low power steering fluid level.

Amazingly, it took me an incredibly long time to search for the info on how to rectify that! So, I humbly aggregate that research here so other noobs can hopefully find it more quickly. If I've made any mistakes, please let me know.

This is your engine:


Look bottom right for the reservoir:


Unscrew the nut remove the cover and fill'er up. Look for the fill line on the inside of the reservoir, about 1cm from the top.


Use actual power steering fluid. The real MB stuff is only a few bucks but many folks have used other brands without issue. In the past, you could use automatic transmission fluid as it was basically the same thing, but ATF now has additives that are not appropriate for the steering system.

The fluid level will rise when the engine is hot so don't overfill!
You went that far......how's the filter?
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,228 Posts
Hint

Filter is about 1/2" below the fluid level in the picture.
 

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Registered
1987 560SL (L.Tonk) [92,700 miles]
Joined
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320 Posts
Discussion Starter #4
I considered the filter (the fluid was so low before refilling I could see it!) The whole thing seemed spring-loaded so I didn't want to mess with it without more research. Is it as simple as undoing that top nut, removing the plastic bit and pulling it right out?

I don't have any experience working on cars, nor a proper working space, so if I don't have detailed instructions, or if the job takes more than an hour, I'm reluctant to begin. Very eager to learn though...
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,228 Posts
I considered the filter (the fluid was so low before refilling I could see it!) The whole thing seemed spring-loaded so I didn't want to mess with it without more research. Is it as simple as undoing that top nut, removing the plastic bit and pulling it right out?

I don't have any experience working on cars, nor a proper working space, so if I don't have detailed instructions, or if the job takes more than an hour, I'm reluctant to begin. Very eager to learn though...
yes
 

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Registered
1987 Mercedes-Benz 560 SL
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973 Posts
I think your understanding of topping off the power steering reservoir is sound. Good job, bud. Here is a little embellishment I think all new owners could use.

This link shows a well-illustrated guide to changing the 560 SL power steering fluid and filter. One important point it mentions is to not overtighten the spring-loaded center sleeve. The nut that secures the sleeve should only be tightened to the point the lid rests about 1/4" above the reservoir, and compresses the spring from there to the point the lid's gasket touches the rim of the reservoir. This keeps the lid from vibrating loose, says the author.

Lots of Mercedes owners fill their power steering reservoirs with Dexron ATFs. I prefer to use the genuine Mercedes Benz power steering fluid myself because I've never seen Mercedes specify anything other than its own power steering fluid in its literature.

Measurement of the 560 SL's max level of PSF is shown in Mercedes service procedure 4611 as being even with the bottom of the Vees embossed on the reservoir's white plastic center sleeve, and this is at full operating temperature, 80C. When cold, the fluid level should be somewhere between that mark and the bottom of the sleeve. The procedure doesn't specify that the engine is running, so I interpret this as engine OFF.

Good road,
 

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Premium Member
1986 560SL with M120 V12 Engine, 1988 560SL Stock
Joined
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10,228 Posts
I think your understanding of topping off the power steering reservoir is sound. Good job, bud. Here is a little embellishment I think all new owners could use.

This link shows a well-illustrated guide to changing the 560 SL power steering fluid and filter. One important point it mentions is to not overtighten the spring-loaded center sleeve. The nut that secures the sleeve should only be tightened to the point the lid rests about 1/4" above the reservoir, and compresses the spring from there to the point the lid's gasket touches the rim of the reservoir. This keeps the lid from vibrating loose, says the author.

Lots of Mercedes owners fill their power steering reservoirs with Dexron III or IV ATF. I prefer to use the genuine Mercedes Benz power steering fluid myself because I've never seen Mercedes specify anything other than its own power steering fluid in its literature.

Measurement of the 560 SL's max level of PSF is shown in Mercedes service procedure 4611 as being even with the bottom of the Vees embossed on the reservoir's white plastic center sleeve, and this is at full operating temperature, 80C. When cold, the fluid level should be somewhere between that mark and the bottom of the sleeve. The procedure doesn't specify that the engine is running, so I interpret this as engine OFF.

Good road,
I haven't seen a pump and fluid that clean in 22 years.:thumbsup:
 

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Registered
1984 380SL
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2,329 Posts
I Just Got Done

I just finished this not 30 minutes ago. I have more fluid changes on my mind as you see from the parts in pic 1.

Just as I was about to begin, the darn tree trimmers showed up, had to wheel it back into the garage and wait. But there's a bonus shot of the Dreadnought. :)

Number three shows the yucky cap and the coffee-like fluid in the reservoir. There was a palpable thickness of brown fiber residue on the cover inside; it is high time this change was done.

I found the nut tightened down all the way which I think is too far. I extracted only a pint of fluid when I hit bottom. I cleaned it, topped it back up, started it and turned the wheels lock-to-lock with no cavitation.

It takes 3 pints. What I will do is drive it then take another pint in a day or so and then another after that. By then it should be pretty clean. (Concentration 2/3rds cubed = 8/27ths of initial contaminent load minus that which is held by the new filter.)

I'm using Dex III as you see. It does say "ATF" in my owners manual pp76. I got enough to do the tranny at the shop, later.

I left more tension in the spring to help hold the cap as per the above, but this is a variable proposition. If the proper fluid level depends on that height, where then is the nominally correct adjustment? Any advice?
 

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Registered
1987 560SL (L.Tonk) [92,700 miles]
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320 Posts
Discussion Starter #9
I went back to get that filter today. Getting the little nut off is a real pain, but once off the plastic bit then the spring come off without issue. For reassembly, there seemed a definite point where the nut stopped which seemed to give proper resistance to the lid when screwed down.

I used an old turkey baster to pull out all the fluid in the reservoir to get to the filter. My old filter came out in three bits, and looked nothing at all like the replacement (Mann) one I was putting in. The fluid was filthy black so I put in more fresh stuff for the stuff I pumped out.
 

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'85 380SL (155Kmiles), '82 240D stick, '80 300SD, '77 240D, '89 BMW 535i, 3 VW Diesels, 2 Triumphs
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1,553 Posts
I believe MB used a "cleanable" , reusable filter from the factory in those days, so yours is probably original (and most likely, never cleaned, if you could really clean them anyway)
 

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Premium Member
1979 450SLC (107 024 22 028551)
Joined
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164 Posts
Hi all,

Noticed that the power steering (1979 450 SLC) is making a loud humming noise when cold (only for the first minute or 2).

Pulled off the cover and fluid appears nice and clean... but the filter appears not to be in straight (tilted up on the left by about 7-8mm). see below photo.

Tried to move it (but not very hard in case I break anything) and it seem stuck.

Is this normal?

Also I assume the fluid level is quite low???

Appreciate any advice.

thanks
DW
 

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Premium Member
1983 380SL, 2000 S430, 1991 420SEL (retired) - RHD
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5,531 Posts
Hi all,

Noticed that the power steering (1979 450 SLC) is making a loud humming noise when cold (only for the first minute or 2).

Pulled off the cover and fluid appears nice and clean... but the filter appears not to be in straight (tilted up on the left by about 7-8mm). see below photo.

Tried to move it (but not very hard in case I break anything) and it seem stuck.

Is this normal?

Also I assume the fluid level is quite low???

Appreciate any advice.

thanks
DW
Yep, it's low- probably the cause of your moaning. The plate s/be level so I'd investigate that.
 

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Premium Member
1979 450SLC (107 024 22 028551)
Joined
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164 Posts
Thankyou. With your note, I pulled a little harder and managed to pry it loose, was shoved in crooked and was sitting quite high compared to where it should have been. Re-seated it correctly, appears to be some sort of "keyway" setup as didn't want to go in until I rotated it. Topped up the fluid. Will see tomorrow morning how it sounds.

cheers
 

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Premium Member
1979 450SLC (107 024 22 028551)
Joined
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164 Posts
Thankyou. With your note, I pulled a little harder and managed to pry it loose, was shoved in crooked and was sitting quite high compared to where it should have been. Re-seated it correctly, appears to be some sort of "keyway" setup as didn't want to go in until I rotated it. Topped up the fluid. Will see tomorrow morning how it sounds.

cheers
Noise gone. Running perfectly again. Happy Days. :grin

thanks and cheers
 
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