ford oil pressure switch

[TwoTone IDI]

does the ford oil pressure switch automatically sweep to the "normal" range during key on and during cranking?

officially fired my rebuild for the first time tonight... SUPER exciting... but while running, to my dismay, the oil pressure "gauge" was hung up on ZERO, nothing, nada.

when i key to "run" and crank its right there in the "normal" range.

there's no reason to suspect a real 0 oil pressure situation... i cranked for quite a while with the plugs out to make sure oil was circulating.

 

[franklin2]

You will never know what you have without running to the store and buying a real oil pressure gauge. If your factory system is working, and your gauge is reading zero, then you have less than 5 lbs oil pressure. If it's reading in the middle of normal, then you have more than 5lbs oil pressure. That's the best info the factory setup is ever going to give you.

If you want to test the wiring and the guage, take the wire off the oil sending unit and ground it to the block. The guage should swing to zero. Take the wire off the ground and let it hang in the air, and the guage should swing to the middle.

 

[TwoTone IDI]

yeah i sort of knew that much. im going to go get an electric gauge tomorrow. i have a mechanical gauge but i dont want hot oil spraying into the cab if the line ever turns loose.

i just wondered if anybody knew whether or not it had a "test" status where it would sweep in certain key positions

it just doesnt make sense that in "run" without the engine on it would show pressure (at least >5 lbs), on start it would show pressure, and then "run" with the engine running it shows 0... unless there is a test process being performed before the engine is running.

 

[gatorman21218]

Yeah go get yourself a good mechanical gauge. I got one from napa and i am quite happy with it. The factory gauge isnt going to budge if pressure is between 5 and 70 psi (an Idiot gauge basically). My S-W gauge reads 20 psi at idle(warm) 40 psi idle(cold) 40-50psi(engine under load).

Tell you what Ill help you with the gauge and you can help me with my slave cylinder

 

[TwoTone IDI]

deal...

i also need to verify my oil level, haynes said to add 15 quarts... which i now know is off by 50%

 

[argve]

it doesn't have a test sequence on start up. the oil pressure switch is nothing more than a switch that makes at 7psi and stays that way until the pressure drops below that. The dash gauge is set up with a biasing resistor so that the needle will move to the center of the needle sweep when the switch makes.


Just so I understand ....

it shows oil pressure with the engine off but the key in the ON position - but then once the engine is running with the key in the ON position it shows no oil pressure.

Sounds like something isn't wired right or the oil pressure switch isn't working correctly...

 

[TwoTone IDI]

that is correct argve. the "ENGINE" light was also illuminated, probably a result of that switch not being made.

the switch is brand new.

ive done some digging and found out the basics on the switch, more or less what you told me above. i guess its ground is VERY important, to the extent that they said to use dope instead of teflon tape on the nipple. thats another thing to check.

 

[OLDBULL8]

deal...

i also need to verify my oil level, haynes said to add 15 quarts... which i now know is off by 50%

With an oil change, add 12 Qts. oil, with a regular size filter, then run it and add oil to bring it up to stick level, with a large filter (the PSD one) it will take about 14 Qts. total. I always leave mine down a quarter inch below mark unless it is up to running temp, oil will expand that much when cold.

 

[argve]

I can remember back from the 2nd IDI Weekend when the mechanic from Stone Wader Ford came out to talk about the diesels and he mentioned that because of the volume of oil in the pan that it is recommend to check the oil when the oil is up to temp because it expands as it's heated. I never really though much about it because of it's such a small volume of oil - typically I deal with industrial equipment that holds 100 of gallons of oil and we account for that expansion - but I know from doing a test on the E years ago that it does move around on the stick some not a lot but does rise as she gets warmer. Nothing like the couple of inches on some the equipment I have worked on over the years.

 

[gatorman21218]

Really? I only add 12 qts even with a PSD filter. Oh and the mark on the dipstick gives you 2 qts leeway.

Two tone if you ever want to look at the factory service manual (mines a 91 but most things are the same) I have one here in ashland.

 

[RLDSL]

that is correct argve. the "ENGINE" light was also illuminated, probably a result of that switch not being made.

the switch is brand new.

ive done some digging and found out the basics on the switch, more or less what you told me above. i guess its ground is VERY important, to the extent that they said to use dope instead of teflon tape on the nipple. thats another thing to check.

Sealer will work better than teflon tape, but think about it, if there is liquid running through the system, the switch will ground through the liquid that is giving conductivity throughout the block and connecting to the end of the switch, so any separation of metal at the threads due to thread sealant shouldn't make any difference so long as the oil is circulating. Same goes for coolant temp sensors that are constantly submerged.

 

[smolkin]

the switch will ground through the liquid that is giving conductivity throughout the block and connecting to the end of the switch

when I put in my wvo temp sensor (mounted in a metal tee on a rubber fuel line) I got no signal until I made an external ground wire off the body of the sensor...so not all fluids will conduct the same, motor oil may be similar. OP, maybe rig up a ground wire and see if it helps?

 

[RLDSL]

when I put in my wvo temp sensor (mounted in a metal tee on a rubber fuel line) I got no signal until I made an external ground wire off the body of the sensor...so not all fluids will conduct the same, motor oil may be similar. OP, maybe rig up a ground wire and see if it helps?

Mounted in a rubber line is pushing it a bit, When the fitting is in metal in the block, the fluids don't have far for a voltage to pass from the end of the switch to the nearby metal that is all around, but if it has to pass through a length of rubber line, that's pushing things a bit. The moving fluid gives a little bit of resistance, a long column of moving fluid would multiply that by a bunch.

 

[OLDBULL8]

Teflon tape is not mean't to be a sealant, it's only for a thread lubricant, which is good when an electrical contact must be made. The only thing bad about it is, if used in a hydraulic system and the sensor is removed then replaced some of the tape may enter the system, if it get in any valve it can hang it up and make it inoperable.

 

[Agnem]

A real oil presure gauge is a must, but I also recommend doing away with the resistor and switch on 87 and later trucks. Solder a wire across the resistor to bypass it, and install a sender from a 83-86' IDI. Then you have a guage that at least moves, and while it does not convey usefull info about presure, it does convey SOME info about habitual normality.