1996 3126B Oil pressure sender and switch.

[darell ottoson]

My oil pressure in my 3126B Cat has all ways been steady at 50 PSI at  normal Highway driving speed. The last 50 miles I noticed it was fluctuating between 30 to 40 PSI. I checked oil,and all was OK. I know this engine will supposedly shut down with low oil pressure to injectors. However I would like to monitor it and maybe get a warning. I think the problem is the pressure sending unit.
    I physically located that unit and notice that at the same port on engine there are two devices. I believe one is the sending unit and the other is the low pressure switch. Silver leaf electronics assured me there is nothing connected to the Cat diagnostic system.
    I also noticed that I have an oil leak on one of the devices. I would like to replace both devices and fix the leak and hopefully indicator problem.  They are in a very awkward to access area to try to get part numbers on. I would like to have new devices available to avoid duplicating the work.
    My question is has anyone else changed these devices and if so do you have  part numbers and source for these devices. One is poking directly out the side of the engine and the other pointing nearly straight off the same piping.
   I am quite certain these are not Cat devices and were installed by chassis manufacture to operate and match  the dash gauge and low pressure indicator.
Any help advice greatly appreciated

[Dave Atherton]

Darell, your not in trouble with the oil pressure low side. On your engine the low side
Is 21 psi. Question coming off your engine oil pressure port is low oil pressure shut down
switch. Dave Atherton Retired Cat Mechanic

[darell ottoson]

Thanks Dave, It looks like I have two devices piped to a 1/4 " Street tee. I think you are saying one is for my Magnum analog dash gauge and the other is a low pressure shutdown to the Caterpillar management system. My magnum dash oil pressure gauge also has a red light low pressure indicator that I have seen flicker at idle. It did not seem to interfere with engine but seems like I would need three devices or sending units?
Thanks again

[Dave Atherton]

Darell, location of your additional sensors are located above location with present add on
shut down switch. Location on sender inbetween secondary fuel filter and Heui pump on
Left side of engine looking from back to front. ( inline with bottom of filter ) next sensor
Location same side of engine along front of engine ECM about 3 inches. What You have, the
first shut down sensor on 1/4 pipe tee is the mfg add on and not Caterpillar OEM
Dave Atherton Retired Cat Mechanic

[darell ottoson]

That clears some things up. Thanks again Dave. I did find out from Mike at Beaver sales in Oregon that the two sensors on the street tee are identical and one sends to Magnum dash gauge and the other to the identical Magnum gauge mounted in the engine service bay on the curbside. I do not have the rv here  at home right now but will look where you described, In the mean time I ordered two identical senders to replace and hopefully fix my slight oil leak and erratic oil pressure on dash gauge.  Thanks again for your wealth of knowledge Dave  I and others greatly appreciate your assistance and advice.
Darell