I have a 1979 ford f100 2WD 300 I6 .

My question is I seen this wire hanging off on the right side of the engine wher the spark plugs are and decided to plug it into this round bulbs shaped part on the side of the engine .i am sure that's wher it goes .and when I pluged it in it causes the oil light to come on.when I plug it up it comes on.when I unpluge it the light goes off.i checked the oil and the oil is fine the truck runs great.i just installed a new battery and she runs smooth now and starts great now too.i know the guy who sold me the truck must have unplugged it.or I might not have bought it.can anyone tell me what part this thing is?would it be the oil lever guage that is just stuck or malfunction ?

 

Hey it sounds like you have just connected your oil pressure idiot light.
You have a red light on the dash if you do not have an oil pressure gauge.
Either oil pressure is low or the wire is grounding out on something and turning the light on.
Another possibility is there a sending unit it's self is defective and needs replaced .
What was the last time you change your oil? Some cheap oil filters like Fram are famous for internally collapsing. I recommend a Ford filter or Purolator.

 

I just had the oil changed last month .when I hooked the wire up I checked the oil stick and it was fine. Thanks for the idea of the wire grounding out.i have never had so many wiring problems as I have had with this truck.my lights are all messed up.i am going to have to put it into the shop to get the wiring figured out.my dash lights are out.running lights ,revers lights are stuck on.its a mess as far as the truck running and driving it drives and runs great smooth.i installed new shocks and it's been great it's just the electrical .

 

Fresh oil and enough oil don't necessarily mean you have good oil pressure. That's based a lot on the oil pump and it's the capacity it can put out. A dying pump or a clogged pickup screen can cause low oil pressure, no matter how good the oil is.

Granted, the sensor simply could be bad. I had one that would sometimes put the needle on my oil pressure gauge below the N on NORMAL and then other times it would be above the L, it just depended upon the sensor's current mood at the given point in time. Swapped it out with a new one, and now it's always on the O when I'm driving. Nothing wrong with my pressure, or gauge. Just a bad sending unit. Point being, those sensors can just die and stop working right. And they're not expensive, maybe $10. They just screw in and out of the block.

If it were me, I'd replace it. It's too bad you have the "idiot" light, and not an actual gauge, but either way it's important to know something is wrong, especially with your oil pressure. Loss of oil pressure can mean the loss of the whole engine.

 

What is the name of the part thanks?

 

It's an Oil Pressure Sensor/Sender/Switch

That look like it?



Oil Pressure Switch - 1979 Ford F-100 | O'Reilly Auto Parts


If it looks like this:



Oil Pressure Sender - 1979 Ford F-100 | O'Reilly Auto Parts

Then someone put the wrong one on there (which might be why it isn't working). The "bulb" shaped one is for the gauge, not the light.

 

I think it's the second one in the picture.

 

If it is the second one, my guess is that the original failed, the oil light came on, and they went and bought a new one. They got the wrong one (the one for a gauge) which caused the light to still be on. So, they just unplugged it and left it.

 

Sounds logical, AB!