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I have done a lot of digging trying to find the proper way to replace the oil lever sensor on my 1998 SL600. I found the PDF that describes how to do it (attached), but I get stuck at "Model 129: intake manifold support - remove" part. It appears to be impossible without the special MB tool for this job, which is not specified in the pdf, but is referenced vaguely in this thread and this thread. From what I gather, the earlier M120 engines had a different sump setup/placement, since in this video, it appears to be a 3 second job to replace once the pan is off (this is the video I initially watched before thinking I could take on this project).
Here is where I'm at: I have the pan off (easy), and looking at the sensor, it's accessible but it has the support directly behind it (see pic). There are three bolts holding the support on: 1 is very accessible, the other two (which are mirrored in their position) are really impossible to get at, it seems. I can't get a socket, a wrench, a swivel or anything, since the opening it too narrow. I've read about removing the sump -- I'm ok doing this, but I would like to know if there is a PDF or something out there that shows this.
I could really use your help, as I ideally don't want to take it the dealer to swap out after putting new oil into it. This also seems to be a common issue, so if it can be resolved in this thread, then more people can benefit.
If anyone knows what the part number for the special tool is, I would much rather purchase it it. Even if it's a $100 wrench as that would still save more money than going to the dealer.
Thanks in advance!
Last edited by Maverick32; Jul 12, 2020 at 09:07 PM.
I'm on my third sensor. I'm sure you have removed the outer slide retainer. Don't bend it or you'll have to get a new one from Germany. They never bend back quite right.
It seems only the 2 O-rings really go bad, but I've always just gotten new sensors and had them installed.
Both times the work was done by DP Auto Repair in Tampa. I always thought the upper pan had to be removed to swap out the sensor, but with the MB tool, it's a simple job with just the lower pan removed,
Call Tony at DP Auto and ask about the tool, I know he has it and how to use it.
Thanks Mahunt. That seems to be the answer most people have said: Take it to the dealer!
Since I'm in Canada, I might give my MB dealership a call and see what they say about the tool. (although if you have a spare moment to call/email Tony and relay the info here, I'm sure countless members would thank you!)
I looked at removing the upper pan, and it seems even more complicated than the other sump.
No, I wasn't planning on doing that! My time and effort to do that would far exceed the cost of going to the dealer. For now, I will button up the oil pan, put some fresh oil in and finish off the Summer/Fall. I'll take it to the dealer sometime in October and I'll ask about the special tool there. However, if anyone finds it between then and now, I'll be forever grateful!
Even after putting in a new level sensor AND spring clip, the fitting still seeped.
I think that if there is any pressure buildup in the crankcase, the level sensor is the first to seep.
I ended up discovering that the 2 PVC port openings in the passenger side valve cover were blocked with engine deposits. Pull the black elbow at the front of the valve cover by the oil fill cap an see if you can insert a WD-40 spray straw into the venturi. They aren't straight tubes, but have a metered opening of about .050 inch each. Make sure they are clean and clear. Make sure ALL your vacuum lines are intact and hold vacuum/pressure.
I ended up replacing all the rubber vacuum fittings on the engine.
That's some great advice. I was actually planning to go through the vacuum lines. My goal with this car is to sloooowly replace all things rubber/seals/sensors as possible. (If I had more room, I would pull the engine and work on it on a stand, but those are only dreams at this point...)
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The pesky oil lever sensor
