I have read all the threads on SLS, and still have a question. I recently replaced SLS fluid with Febi fluid. I did this after put in new seals in the SLS pump (not the valve in the back, but the pump which sits on the engine head). The condition of the pump shaft and internals looked very clean and shiny. After a few days, my sls fluid is dark.

I believe the previous fluid, prior to changing pump seals, was seriously contaminated with engine oil going past the shaft seal in the pump and into the SLS system. That's why I replaced the seals.

Here are my questions

1. In a properly operating SLS system, will the SLS fluid stay clear for a long time....I usually think of hydraulic systems as similar to transmissions...fluid should always be clean and clear. The unique aspect of the SLS system is that the only barrier between clean sls fluid and very dirty engine oil is that shaft seal....maybe it is normal for little bits of engine oil to get into the SLS system causing it to go dark very soon (this doesn't sound right to me!).

2. After I replaced pump seals and flushed system only to have the fluid turn dark again....could there have been enough contaminated oil in the accumulators to contaminate the system? (If so, I really need to flush the system with a lot of fluid....Febi stuff gets very expensive). Or do I still have engine oil getting past the pump seals?

Thanks,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

Did you empty the shocks?
They hold a bit of fluid.
The cells dont hold fluid when there is no pressure in the system.
When I did a cell change following a failure caused by an indi putting atf in the system. It was necessary to empty every thing, rinse with fluid, rinse again & then re assemble & fill with fresh fluid.
The filter needs to be changed as well.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

There's prolly about half a litre in each actuator which will more or less stay there unless you remove it and drain it out.

The spheres will drain completely when the system has no pressure. The valve will contain a little and so will all the pipework.

I completely drained my actuators but did not wash them out, my fluid was dark, but not black.

Its had fresh fluid in there for a month or two, which now isnt water-clear like it was when it went in....

Only way to insure the fluid stays clean is to remove everything and wash everything through with fluid and blowing compressed air through the lines...

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Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

I just ran new fluid in as the old fluid ran out. Sounds like I need to do it again, just to make sure I get the max old fluid out.

Although...its been about 1000 miles and its still clear.

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77' 300D, "Cartman" SOLD @ 150K (didn't know what I had)
83' 300SD, "The Superdon" 325k+ @ 28mpg
95 E320 wagon, "Millennium Falcon" 231k+ @ 24 Mpg
95 E300D, "Sherley" 308k @ 33.69 Mpg, currently anticipating a head
99 Suzuki Intruder "Trudy" @ 45 mpg

If its clear, I wouldnt worry about it....

It takes a little while to discolour if the old fluid was dirty, but less than a thousand miles I reckon!

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http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

The spheres will drain almost completely- there might be a 1/6 liter left in both of them with no pressure. If one sphere is bad it'll hold maybe 1/4-1/3 liter by itself- but the system may still appear to function as designed because the remaining sphere will hold the car at the proper by itself.

What's difference between sphere and actuator? Looking at schema in fsm for these I see no sphere.

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What Would Rudolph Do?
1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius

I assume you mean sphere and accumulator. These are both terms used for the SLS pressure cells.

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How did you flush the system Mark?
The line going to the top of the fluid reservoir is the return. I connected a piece of fuel line to the return line and ran it to a 2 liter drink bottle. Ran the wagon and poured in fluid until the fluid coming out was clear. I changed the filter, flushed a bit more and it has been fine. Fluid is in the lines, the accumulators and the struts. Some in and out through the valve. I would think it would flush completely.
Andrew is now our SLS expert!!

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

I too have dark black fluid (real bad, looks like used engine oil) in my sls res tank.

Symptoms:
1) For the last week or so it has been weeping considerable fluid from the tank cap after it sits once I've been driving. It sags overnight too.
2) A bit of fluid leaks out the bottom of the pump as well.
3) No leak at valve except, 1 SLS line has been soldered on the line side of 1 of the fittings on my SLS valve (not sure I will get the line off in 1 piece), but does not appear to be soldered to the valve body itself.
4) car feels like it hits the ground "hard" when I hit a pot hole.
5) Rear of car raises up when I start it from a long rest (a few days)

My directions that came with the Pump kit say to "flush BEFORE you take the pump out and rebuild it or you may be doing it again" No problem there, except that I would like to rebuild the SLS valve, check the rear accumulators, and replace that soldered line too if need be.

* I need advice on the order in which I should do the work*

Soln 1: If I flush first, fix pump, then fix the rest, I will lose a ton of new fluid from my old spheres, lines, etc.

Soln 2: If I fix valve and check accumulators (possibly replace), then flush, then fix pump, am I hurting my new valve and accumulators by passing crud through them?

Soln 3: Can I partially flush the system to a point past the pump, fix pump, then pull valve and spheres, then continue system flush?

Soln 4: Should I just flush 1X, fix everything, flush again? seems like a waste. Any suggestions on what order to do the work as to minimize new fluid loss or potential new part damage?

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1979 300TD

For flushing use mineral oil. Much cheaper than the MB/Febi stuff.
The best situation would be to drain the system, re-seal the valve, replace the accumulators, and seal the pump. Then flush, and refill with the good stuff.

The pump will be the hardest part to remove and re-seal. The valve removal and re-seal are pretty easy, and accumulator remove and install are easy.

You could also do the valve and accumulators at the same time. Flush and fill with mineral oil. Then sometime in the near future deal with the pump, and then refill with the MB/Febi fluid.

If you have lines that have been soldered or welded on, be prepared to deal with a leaky line. Might be time to shop around for a replacement from a junkyard just to be safe.

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Thanks,
Got the res tank out last night and cleaned it. I Drained the system. Tackling this stuff this week. Thanks for the advice.

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1979 300TD

my sls valve kit has still not come from MB so I'm doing the pump first. After flushing I pulled the pump and thick black oil came out (not sure if normal after flush). It was only a very small amount. My question is this:

On the engine side, an allen bolt on the rt side (driver's) is present, but there is a hole 180 opposite it in the flange. Is it missing a 2nd allen bolt? It is hard to tell from the diagram I have. I sure hope not. don't want to put then pump back in until I have a solid answer.

Thanks

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1979 300TD

I've never had mine apart but from looking at yours, I think there should be a second allen bolt.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Nope,
No bolt, "the hole leads to the timing chain area and should not be obstructed" is what my MB mechanic told me. Thank god. Now I'm not sure how my pump was failing. the seals in it it were rock hard, but other than that they looked brand new. There is a small ding in the alluminum edge of the lip seal. Hope the pump is not shot. I'm going to put it back together today and check it out.

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1979 300TD