w124 oil pressure sender / sensor

[tjamesbo]

I am going to test the Oil pressure Sender on the 124
I think I have located it by and above the Oil Filter Housing
2 Questions
Is this it ?? see piccie below

How does the connector come off ? / unplug (so that i can test the resistance of the sender and substitute a resistor to check the gauge ) pull / twist dont want to break it !
Thanks Boyd

 

[tjamesbo]

Also any Ideas why there is a connector at the front underneath the front cover that isnt connected anywhere ????
here it is

Thanks

 

[robparker]

No thats not it, it looks like this:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=150693856626&ssPageName=STRK:MESE:IT
And I think (could be wrong) that unusually on that engine they are located on the o/s of the engine, and not near the oil filter housing.

 

[wireman]

May be of use 102/103/602/603 engines.

Resistances of pressure sensor as a function
of oil pressure.
Pressure (bar) 0 1 2 3
Resistance approx. 10 69 129 184

 

[tjamesbo]

Thanks I picked that up off one of your older posts I think , ....... But mine is the 111 Engine in the 93 220TE so are those still the values ? I just bought the resistors you mentioned off Ebay last week

 

[wireman]

Don't know for sure, the numbers are for all engines in 1992 US 190's but if it looks like the Ebay item its just like the ones on my 124 and 201.

Replacing the sender with the fixed resistors will test the indicator not the sender.

Why do you suspect troubles with your sender? and what is your oil pressure gauge doing wrong?

 

[tjamesbo]

As well as reading low it sometimes fluctuates quite a bit eg occasionally goes up before going down when deaccelerating
Always on 3 at start up but once hot can be virtually zero at idle

 

[television]

That is a faulty sender identical to my 140, mine failed during an oil change

 

[wireman]

+1 for dead sender, or a possible wire fault near to its connection, shorting to earth was the reason on my 124, fixed by washing off the grime from the senders terminal and tidying up the wires and connector.

 

[tjamesbo]

I have located it here is a location piccie

Next step to clean and degrease and remove connector

 

[tjamesbo]

Here is a close up degreased wire is in good condition to loom I have pulled the top cap off the connector and have now removed connector ( pulls off )

Now just got to wire up the resistors and check the guage end first

 

[tjamesbo]

OK the resistors have gone onto the wire, and other end connected to earth results as follows;
10ohms = O bar Checks out OK
180 Ohms =3 Bar Checks out OK
68 ohms = 1.5Bar previous posts suggest this should be 2 Bar although check resistances were not quoted for the M111 engine

All readings Rock steady and same from ignition on to running no variation with revs so Voltage obviously stable .

Conclusion on basis of above favours the replacement of the Sender Now
£35 from Euromerc is favourite .
Access to the 17mm Nut at the back of sender is very poor even a stubby wrench has only about 1cm movement . I have ordered some crows feet wrenches . Hopefully these will fit otherwise I am going to have a job cracking it off ( and tightening the new one ) .
Should I put some sealant on the top part of the thread for the new one when it goes in

 

[tjamesbo]

New Sender from Euromerc £35 , half the price of the MB Dealer and with the help of a 17mm Crowsfoot ( preferably a thin one ) The old is off and the new is on
What a Difference 3 Bar all the time even after an italian Tune Up it only dropped to about 2.5 Bar At idle in Drive .
So the Engine is good for another 100K :wink: Jus got to sort out next
Steering Play
Rattley Cat
Front Wings and Rear Arch ( next summer )
Boyd

 

[syncropaddy]

Total bitch of a job removing that sender!