Hi, further to my thread about flashing the suspension system, can anyone tell me how could it happen that engine oil got into the hydraulic suspension system when the oil seals are intact. I drove my W124 230TE at an average speed of about 90km per hour for a distance of about 200 Km. At the end of that trip, the hydraulic oil reservoir was filled to the top with engine oil mixed with the suspension/hydraulic oil.
When I got home I suspected that the oil seal at the back of the pump may be severely broken. But when I brought it down to check, lo and behold..... the seal was intact !!! Is the pump that strong to be able to suck in engine oil and fill the reservoir to the brink ???!!!
I hope someone who clearly understands the suspension system and knows the installation of the pump is out there to be able to get into the groove of what I'm saying.
Since your SLS is different from that on my 300TE, I looked in the Haynes manual, which talks about the SLS on your four-cylinder petrol engine. There is no other way for engine oil to get into your SLS other than the pump. Just because the seal on the pump is intact doesn’t mean oil can’t be forced through it. It may have shrunken over time with all that engine heat. Replace that pump seal, and also the inner sealing ring while you’re there.
Also, is there is a seal on the engine by the camshaft and the front engine cover? Replace that too if so.
Please post back after you fix it to let us know how it worked.
Yes, I replaced the oil seal out from a repair kit and it works well... at least engine oil did not get suck into the hydraulic pump this time. It was a simple as that. But a question still rings in my mind.... if the engine oil did get suck into the pump, why didn't I have any trace of hydraulic oil coming out of the pump ?? Maybe so because the hydraulic oil did not have enough pressure so as to push it out... just guessing !! Any comments ??
Also, there is no oil seal at the end of the camshaft (and the engine cover). A closer look at it reveals that a small quantity of engine oil actually "splashes" on the back portion of the hydraulic pump (and right smack onto the oil seal in question) but slides right back down into the cylinder head when it reaches a specific quantity.
On another note, do you know the best way to get to the sunroof without ripping off ceiling upholstery unnecessarily ?? My sunroof got stuck before getting fully shut and a small gap remains. I think it needs pulling down and some metal works. If you had the chance to pull down one in the past, please share it with me so I do not destroy any interior upholstery.
I had the same thing happen on my W126. The hydraulic (Nivelo) pump seal and inner workings were worn out, and that allowed the engine and hydraulic oils to mix. It's quite a common problem...
I recommend changing motor oil ASAP as well as reaplacing the hydraulic pump or getting it fixed (not an expensive job - around $150 here, used one costs $15 on a junkyard).
Since your SLS is different from that on my 300TE, I looked in the Haynes manual, which talks about the SLS on your four-cylinder petrol engine. There is no other way for engine oil to get into your SLS other than the pump. Just because the seal on the pump is intact doesn’t mean oil can’t be forced through it. It may have shrunken over time with all that engine heat. Replace that pump seal, and also the inner sealing ring while you’re there.
Also, is there is a seal on the engine by the camshaft and the front engine cover? Replace that too if so.
Please post back after you fix it to let us know how it worked.
Easy job ! allow about an hour and a half (taking your time) I removed the pump from the engine without disconnecting the hydraulic lines. Replace the large and small "o" rings the pump gasket and internal pump oil seal (very obvious when it comes apart) Parts cost me 15 euro .
Engine oil in the suspension system 
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