W124 oil pressure sender...drain oil first, easy install or not? - PeachParts Mercedes-Benz Forum

G-Benz · #1 03-31-2003, 10:59 AM

Got my sender from Fastlane a few weeks ago...haven't had time to install, but want to tackle this sometime this week.

As the thread title states, do I need to drain the oil first to install? I don't want to see the opening scene to the "Beverly Hillbillies" when I take the old one off.

And how about removal? The sender wire wasn't very easy to access when I rebuilt the harness, so is removal of other components necessary?

G-Benz · #2 04-01-2003, 10:25 AM

bump...

Anyone? Anyone?

Looks like I might have to go it alone. I will post results...

MikeTangas · #3 04-01-2003, 07:14 PM

Sender is easy G. No need to drain the oil, just the filter canister. Get it slightly warmed then loosen the center bolt on the canister, crack open the top and let it drain. The sender is threaded into the filter housing and take a 17mm or a 19mm open end to remove. Only a small amount of oil will come out when you pull the sender, as long as you let the canister drain.

Duke2.6 · #4 04-02-2003, 01:00 AM

Draining the filter will make a HUGE mess. If you can access the sender with the filter installed, just remove the old sender with the new one readily at hand, plug the hole with a finger and install the new one. You'll probably only lose a few cc of oil and you might be able to catch most of it with strategically placed rags.

If it's easier to install the sender with the filter off, puncture the top of the filter and give it a half hour to drain. This is SOP for my oil changes, and I never spill a drop. After you install the new sensor, install a new filter.

Duke

MikeTangas · #5 04-02-2003, 12:13 PM

Correct me if I'm wrong, but isn't the filter on this car accessed from above? I know the filter on my 86 is. Cracking open the top cover allows the oil to drain back into the block which doesn't make a mess.

Duke2.6 · #6 04-02-2003, 12:45 PM

103 engines have an "upside down" spin on filter, so loosening it will cause all the oil to drain out and run down the side of the engine.

For this type of filter installation punching a hole in the top of the filter will allow the oil to drain down, so when you remove it, there is little spillage.

You may be talking about the replaceable cartidge type filter like the one on my erstwhile '84 190E 2.3 with the 102 engine.

Duke

MikeTangas · #7 04-02-2003, 02:19 PM

Guilty as charged. Forgot about the change to spin on filters. Everything I have has good old cannisters with replaceable cartridges.

Duke2.6 · #8 04-02-2003, 02:42 PM

Wish my 103 engine had the replaceable cartridge. I prefer them.

Duke

G-Benz · #9 04-02-2003, 03:31 PM

I'm referring to the M104 engine...probably should have made that clear earlier...

...so now I'm confused?

Mine screws on with the hollow end down (solid end up). So when loosening it, am I in for a mess or not?

Duke2.6 · #10 04-02-2003, 04:02 PM

We seem to be having a vernacular problem with the filter orientation frame of reference.

Consider the location of the rubber gasket on a spin on filter. If in the installed position it is "down" relative to the closed end of the filter, the filter will quickly drain when you unscrew it enough to break the seal with the filter pad.

The first thing I do on an oil change is punture the top (closed end) of the filter with a big nail and a couple of taps with a small hammer. Then while I'm removing the pan plug and draining the oil the oil in the filter will drain down to the pan and out. I usually leave the plug off at least 10-15 minutes, then jack the corner of the car diagonal from the pan drain plug up to get the last few ounces out. Once the plug is back in, I pack a couple of rags around the filter pad, loosen it with a cap wrench, then spin if off by hand. At most it will spill a drop of two on the rags.

Duke

G-Benz · #11 04-02-2003, 11:51 PM

Total amount of time: 10 minutes!

Install instructions for future searches on this issue...

Oil sender replacement for the W124 M104-series engine.

Step one: Jack up driver's side of vehicle.

Step two: Remove air deflector shroud underneath engine.

Step three: disconnect sender lead from sender (may take a flat-blade screwdriver to do this since there is miniscule room for leverage to pull it from the fitting).

Step four: Unscrew the sender using a 17mm wrench. Preferably, a short one...there is little room for untightening (or tightening). Fortunately, one or two twists will allow you to loosen it by hand.

Guess what? Not a drop of oil dripped (or poured) out! Perhaps jacking the car forced the oil to the passenger side of the car. Or maybe the fact that I didn't drive the car for a day (it's been SL weather lately

).

Step five: Screw the new oil sender back in. This is the hardest part of the job, because the tight confines require a bit of trial-and-error on sender thread orientation. Eventually, it will hand screw right in and a couple of twists with the wrench seats it.

Step six: Reattach the sender wire.

Steps seven and eight: Reinstall the air deflector shroud and lower the car down from the jack.

The gauge needle no longer pegs to "3" when I turn the key (without cranking the engine). A test drive confirms that the gauge now operates as it should.

Thanks to all for coaxing me through a task that I had procrastinated on for nearly three weeks!

xp190 · #12 04-03-2003, 07:55 AM

I'm gonna be doing the same thing on my 190 in the next few days hopefully. I need to replace the oil pressure sending unit as well as the oil level sending unit, and a bunch of other components. Anyone have any clues on how to do that?

I figured that in order to replace the oil pressure sending unti I will have to pull out the entire oil gallery that the filter and pressure unit sit on. It would be the easiest since there is not enough room to get the filter or the unit off or on. I got some gasket paper to make a new gasket for the gallery once it's off. Anyone do it this way before? I'd love some feedback.

Second issue is the oil level sending unit. I know I have to drain some oil, but is there an o-ring there or something? I didn't order one, and if there is, I wanted to know if any o-ring will do, well same size of course, I hope I can find one at a local parts store.

xp

Robert W. Roe · #13 11-21-2003, 09:52 PM

I'm getting zero readings at idle. Could this be the sender? I know the book says as low as 0.3 bar is ok, but mine is going right down to the peg, for a while now. Engine sounds fine. This is driving me paranoid... thanks, Bob

smp · #14 09-15-2013, 03:03 PM

Forgive me for digging up an old thread but maybe this will help those looking for info on replacement of the oil pressure sender on the m104 engine. I found the answer in another thread so posting it here for anyone else looking:

Quote:

Originally Posted by G-Benz

Your idle pressure should be reading around 1.5 - 2.5 bar depending on the viscocity of the oil you currently use.

I've replaced the sending unit on my M104 (300E) twice. The unit costs around $65-$70 and can be replaced in less than 30 minutes.

Access to the unit is under the vehicle. A bit tight to get to as you have to maneuver around the starter and the harness. I don't remember what wrench size to use, but make sure it's a short one...not a lot of room to turn, but after a couple turns, you can hand loosen and remove.

from this thread: http://www.peachparts.com/shopforum/tech-help/223277-oil-pressure-could-read-zero.html

edit:
I just did the job, it's as described. W124 e320 wagon. 17mm wrench. Stubby preferred but I did it with a full length wrench, it was difficult but I got it eventually. It's hand contortion this job, not gonna lie my hand was cramping up trying to thread this thing back on. Get the car up as high as you can, you need to be able to manoeuvre. I did mine after draining the oil and removing the filter because it was oil change time anyway.

thayer · #15 09-15-2013, 08:00 PM

I did the same job as part of the Starter Harness replacement. Did the oil level sensor at the same time. Yeah, you will pull back a scratched/bruised forearm but its just a simple screw job for the pressure sensor. The oil level sensor had a couple of bolts and I can't remember if there was a gasket. I cleaned everything up and so now no leaks, and good info from all the sensors. The PO replaced the main engine harness, but not the starter harness.