hello, my oil pressure does the notorious drop when warm, i replaced the switch, same thing still, rebuilt the engine because of other issues, replaced pick up and pump, still the same issue... when i replaced my switch, i noticed it had a different size head on it than the original, but it still does the same thing as the original did. when i purchased it there are 2 different sensors, one for a gauge, one for a light. my truck has the dummy gauge, but it works just as a light would correct? i'm wondering what the difference is between the switches, and if the gauge type is for a real working gauge, and not our dummy gauges, or if it requires the switch for the type with a light? as always, thank you in advance!

 

You need the switch that is "for a gauge, but not really".

I don't know if you are familiar with electrical terms so here's a quick lesson. A switch is said to be Normally Open (N/O) or Normally Closed (N/C). This refers to the state of the contacts when it is just sitting there NOT being actuated by anything, in your case oil pressure.

With an idiot light, the switch is N/C and will open with oil pressure present to turn off the light.

With a DUMMY GAUGE (what your truck came with) it is N/O and will close with oil pressure to drive the gauge pointer off the LOW mark on the gauge face.

With a REAL GAUGE (which you can convert yours into) you do not use a switch at all but rather a pressure transducer which is called a "sending unit" in parts store talk, even though it doesn't actually "send" anything. Rather it varies resistance to ground which causes the gauge needle to deflect one way or the other.

So if you have a gauge and haven't converted it to work like a real gauge, you need a N/O pressure switch. This is probably listed for trucks with a gauge in the parts store catalog.

 

ok, thats what i thought, thanks, looks like i'll probably swap to the sending unit and solder the board to make it a real gauge, i guess i don't understand though how it could be saying it's below the pressure required to close the switch when it warms up, it's 6psi where it closes right? i have no knocks, no rattles, everything is fresh in the engine, it just confuses the hell out of me...

 

Get a sending unit and a proper gauge, autometer, vdo, isspro, glowshift, etc. "Normal" isn't really an accurate measurement of anything, especially oil pressure

 

just ordered a sunpro mechanical gauge kit, comes with tubing, all fittings and stuff too, for cheaper than i could find a sending unit... hopefully my ACTUAL oil pressure wont scare me. lol

 

i gave up on my gauge years ago. it will actually go up when its 100 + degrees out side and i drive up town, hey thats good right. i remember reading years ago about being to convert the dash gauge to read right. you use some sending unit and do some wiring on the cluster, but for me its not worth it.

 

I don't care for running a pressurized oil line into the cab... had one blow apart on me once. Just a thought.

I suggest a 1/4 turn ball valve on the block, so that if the tube does let go at least you can drive it home. Unless you carry tools with you... then just keep a pipe plug in your tool bag and you can use that if needed.

 

hotrod, yeah, you replace your pressure switch with an older model sending unit, then solder a jumper across the resistor on the back of the dash panel, i didnt want to do that because i still wouldnt know what the actual pressure would be reading, and dixie, i know what you mean about that pressurized line in the cab! i'm thinking about just using the new gauge for a couple days to just get an actual reading on my pressure, then just plug it, or put original pressure switch back in. it just scares me wondering if somethings goin wrong in there right now after a fresh rebuild ya know? i've driven this truck 4 1/2 years like this already and never had an issue with parts staying lubricated, but i just need a verification that my internals are good!

 

i hear you. you just what the real pressure is.

 

Yeah I did the same thing. I do have the factory gauge converted over but it was acting scary so I ziptied a mechanical gauge to the cowl and drove it like that for a couple days to put my mind at ease. Turns out most aftermarket oil pressure sensors are made by the same JUNK company. One day I'm going to find a GOOD sensor for it. Yes I can get an aftermarket gauge but I don't like having unused gauges in the panel either.

 

I am trying to replace my dummy gauge oil pressure switch, every switch I find at my parts store in normally closed at no pressure, my gauge goes to normal when a ground is applied to the switch connecting wire, which I need a open circuit while not running and closed when running, does anyone know of a part number as internet searches don't give details of NO/NC, thanks

 

I’m not sure what you’re doing. Are you saying that grounding the wire only moves the needle to the middle of the gauge? It should peg the needle to the high side.

As a side note you should have started a new thread. This one is nine years old.

 

Lineman92 I looked on RockAuto and there are two options, one for a light, and one for a gauge. You need the one for the gauge.