Oil Pressure Gauge and Sending Unit Troubleshoot And Repair GM Trucks

Just a simple walk along video tutorial showing how to troubleshoot, test, diagnose and replace the factory oil sending unit for your squarebody Chevy and GMC truck.
This is for 1978-1987 trucks and GM cars using a factory oil pressure gauge.

[@American-OutdoorsNet]

Glad to hear! Thanks for tuning in.

[@pauldavies9464]

Great video explained all very easy to understand just got to fix my Rover P5B now so I can see some oil pressure the Buick engine

[@mibars]

Late square bodies (last facelift) use different style oil pressure sending unit, which combine function of a sending unit with an on-off switch for a fuel pump relay. General principle of operation is still the same. Just checked the readings of my replacement sending unit and it seems to go from 0 to 90 ohm sort of linear between 0 to 90 PSI even though gauge reads only up to 60. There are also some quirks like the resistance changes in noticeable steps and there is a visible hysteresis between pressure going up and decreasing.

[@rimfireshootingmk]

My pressure dropped to almost zero the other morning on a 65k mile GM Goodwrench motor. Got a new sensor and sender, did the tests, everything. Made me think it had to actually be the oil pump. For fun i pulled the bezel and then the oil pressure gauge. Put the oil gauge back and then started. Pressure was back. Cleaned, contact greased and polished everything. $73 in new sender and sensor too but i didn't have drop that pan.

[@nickvivid]

Thank you for this video. Helped me troubleshoot a shorted sensor wire on my G10.

[@American-OutdoorsNet]

Glad I could help and thanks for watching.

[@andygreen1769]

Great vid!

[@thisguytrucksoldtrailer6875]

Thanks, this helped a lot.

[@Keeterbob]

Ok. I just installed a new sensor. With the car running and the tan wire disconnected I get 86 ohms from ground to sender lead. At idle. I know pressure is good. Tested with mech gauge. Is 86 high for idle? Mech gauge had pressure at 26-30. It’s on an 88 Camaro with a 5.7.

[@American-OutdoorsNet]

Did you check the sending unit prior to installation? What is the dash gauge reading? Go back to the 7:50 second mark of the video.

[@Keeterbob]

4.3 ohms. But I think I found the issue. At the gauge I am getting the same ohms that I am at the sender 86-92. This leads me to question the gauge itself. It’s not getting the signal from the sensor. I unplug the signal wire and the needle pegs. Plug it in it barely comes off zero

[@willuhl2086]

😊😊😅

[@omfgursodumb]

Hey thank you for the video. I was hoping to ask a question or two. I bought an 84 c10 with the factory 305. The guy i bought it from did a lot of questionable work. Im. Currently trying to figure out my oil pressure Guage. Looking around in my manual oil pressure sending unit with a tan wire and a pressure switch. I believe i found the wires for them. Do they both hookup to the same spot next to the distributor? In the spot i had a pipe nipple capped with a valve stem core remover lol

[@American-OutdoorsNet]

There should only be one wire with a small rubber boot (if OE) that plugs into the sending unit next to the distributor. It is in the wiring loom running behind the egine.