Guys, I’m trying to figure out some senders that I have left over from my MPI setup. I have not looked at the wiring harness post disconnecting the EFI harness so when I pull it down from my attic, maybe I’ll get my answer.

Down at the oil filter pad, there was a temp sender installed in one of the truck oil cooler ports. It had a dark tan wire attached to it indicating temp per the color code. Curious... does the MEFI 3 monitor oil temp? I don’t recall seeing it in the Techmate. Anyway, I have not added the sender back into the mix, though I may so that I can use it for a gauge (anyone know the range?).

I have that sender as well as two oil pressure switches. There is one just behind the intake (used for the audio warning system) and another at the port above the oil filter pad that is combined with the gauge oil pressure sender (I’m assuming this is used by the MEFI 3).

Any thoughts on this stuff?

Thanks!

Stock systems didn't monitor oil temp but it could easily be added into the system looking over the inputs/outputs of the MEFI 3 system. Say for example pin-out # J2-8 uses a Tan wire which is a Discrete Switch for transmission over temp switch..., Last page Tan/White into Tan, Boatinfo - Bulletins for marine engines and boat related accessories!

Michael's Tractors (Simplicity and Allis Chalmers Garden Tractors) - Mercruiser MEFI-3 ECM Delphi 16237009

That's interesting and solves a mystery. My engines were take-out MIE's and that connection was seen in the Techmate. My transmission switches were hooked up to the audio alarm system that was original to the boat (tan w/blue stripe wire). It looks like the J2-8 connection was used to alert on engine oil temp over-temp; pretty good thinking. I never heard it the ECM alarm go off solid (only beeps for a knock sensor) and I ran the boat pretty hard at times... I wonder what the switch range was. I know transmission is set for 195.

Interesting find! Thanks!

Happy to try and help...)
Being the engines were MIE's and placed into stern drives probably during the install went form "easily be added into the system" to what should we do with the existing temp overheat system...Lets monitor the engine Oil temp.

Generally speaking Mercruiser used about three basic temperature settings depending on application and where used...(There are a few other set ranges out there too + aftermarket, etc.) But the three common were 196, 212 & 230 (< or I believed it to had been 235 degrees personally).

Searching most of the MIE transmissions parts catalogs comes up as Merc part number 87-88031 (Switch Assembly) which is considered a High Temperature Alarm Switch at mentioned 230 degrees as noted here,.....https://www.marineengineparts.com/me...witch-assembly
https://www.mercruiserparts.com/88031-switch-assy

Is this what your switch looks like?




48952

Mine are labeled 102700 which I believe is a temperature sensor with a range of 100-240 degrees. Uses a stud and ring terminal. This appears to be a sensor, not a switch, so the mystery continues. These wouldn't work in the oil system and wouldn't work for the alarm trip on the ECM unless the switch is reading actual temperature (the transmission switch is just that - a switch).

My transmissions have the switch in your reply and are connected to the alarm systems.

Here’s the switch that was in the oil passage:

Correct.

DATCON TEMPERATURE SENDER SENSOR 102700 ~ Low Range ~ 100-240°F ~ 3/8 ~ OEM