773G low oil pressure engine shutdown

[sawright]

2002 773G turbo with 1350 hrs. started throwing low oil pressure codes. Went into engine shutdown. Tee'd a mechanical gauge in with the sender and it reads 60psi. So I suspect the sender. Is there any way to test the sender? From what I understand, that little part costs $175 OEM from Bobcat. Anybody know if an automotive substitute can be made to work? They are usually more like $25. Thanks! Steve

 

[OldMachinist]

You can use a ohm meter to check the sender. Screw it in to a pressure regulator, start with 0 psi and slowly increase the pressure(75 psi max) and read the ohms.

 

[sawright]

You can use a ohm meter to check the sender. Screw it in to a pressure regulator, start with 0 psi and slowly increase the pressure(75 psi max) and read the ohms.

Thanks OldMachinist !! I'll give it another check. I did verify I had 8vdc coming into the sender. With 0 psi (machine off), the sender read 11.4k ohms from A to C, 1150 ohms from A to B and 13k ohms from B to C. A is the +vdc, B is ground and C is the tap. Those are considerably higher than 3 ohms, so maybe that is saying something. I'll check under pressure and see what that says. Thanks.

 

[OldMachinist]

Thanks OldMachinist !! I'll give it another check. I did verify I had 8vdc coming into the sender. With 0 psi (machine off), the sender read 11.4k ohms from A to C, 1150 ohms from A to B and 13k ohms from B to C. A is the +vdc, B is ground and C is the tap. Those are considerably higher than 3 ohms, so maybe that is saying something. I'll check under pressure and see what that says. Thanks.

The chart is for the older Boss machines so the values may be off. I haven't been able to find any info on the newer senders. But hooking it up to pressure should show if its working.

 

[Tazza]

The chart is for the older Boss machines so the values may be off. I haven't been able to find any info on the newer senders. But hooking it up to pressure should show if its working.

Sadly the senders are rather expensive..... The standard go or no go senders are cheap, these actaully tell the computer what the pressure is, not simply within range or out of range. I have never done the exercise of looking to see if they are available after market, it would be good to know if they were though....