Cat 3126 rear main install tool

[Nige]

The parts manual for your particular engine shows two 3/4" thread plugs on the top of the flywheel housing at approximately 10 & 2 o'clock.
It does not show any sensors mounted in that location. I suspect you are correct and that the sensor is a Grove part to provide a signal for the tachometer. In which case it will have nothing whatsoever to do with the engine starting issues you are experiencing.

 

[56wrench]

that old 3/4 unf sensor looks the same as the tach sensor used on some older ag tractors and combines

 

[Nige]

that old 3/4 unf sensor looks the same as the tach sensor used on some older ag tractors and combines

That's where the 4P-5820 Part Number came from..........
Still not totally convinced it's a Cat sensor.

 

[crane operator]

Grove man confirms it is a grove part, not Cat. Service guy (Grove) says its not tied into ecm/ no fuel. Looks like I'm going to have to have the Cat man come out with his computer and play the "rabbit season- duck season" game on whether its a grove issue it won't run, or a cat issue.

I'm betting we've pulled a wire or pushed it out of place on the big ecm plug. We had it unplugged and left everything else on the engine, we did have a few grounds unhooked and other wires, fun fun. Thanks everyone.

 

[56wrench]

to me, it looks like a generic speed sensor used by several tractor/combine/equipment manufacturers. it looks the same as my old White Farm Equipment tractors and New Holland combine. i have bought replacements from a business that repairs ag/industrial electronic tachs, gauge clusters, etc

 

[Nige]

If you want to start ringing wires out then you can have an electrical schematic for the engine if it helps. Just ask.

 

[Truck Shop]

That Tach sender is just a standard unit found in trucks going back 35 years, it's just a two wire there is also a three wire type. Any truck parts outlet should have it.

https://mpparts.com/part/7125500-ma...ntent=mpparts products#lightbox-gallery--04-1

 

[crane operator]

It LIVES!

Local dirt contractors mechanic came by early this week, and hooked his computer to it. No communication, , he says his won't read anything older than 2015 That totally leaves out my equipment repertoire.


My good man Jim stuck with it, and found the hot wires on the starter solenoid were loose. The starter had stayed in the crane just pulled off to the side and hanging in the frame while the motor was out, but evidently swung enough to loosen the wires, we never unwired it.

It was getting enough 12v to crank, but was evidently losing something vital and wouldn't give it fuel. Thanks for the help everyone.