Oil Pressure Sender Replacement - 190E 2.3-16

[JimSmith]

My son just replaced the chain tensioner on his 190E 2.3-16, which went very well thanks to the instructions posted here. A day or so later, after also replacing the battery, he noticed the oil pressure did not rise after starting the car. So he shut it off. I returned from a business trip and was treated to a demonstration. No odd noises, no chain slap, runs smooth, but no oil pressure. Disconnected the electrical signal line from the sender and the gauge pegs at 3 bar. Connect it and nothing. So we figured it was the sender. Anyone replace one of these? Looks like we will have to bend up a 17 mm Sears Craftsman wrench as there is next to no room for frozen fingers to get near the hex on the back of the sensor. If anyone has any hints, please let me know. Thanks, Jim