Where is the oil pressure sending unit on a 258?

[macdude443]

Looking to connect the gauge package harness.  I know where the 3-prong switch is on the passenger side above the filter.  Also, what would the purpose of the sending unit be if the car didn't originally have an oil pressure gauge?  I believe the Oil light is wired to the oil pressure switch, as is the choke.

[vangremlin]

The oil pressure switch, or sending unit, for is located right behind the oil dipstick.  It controls the Oil idiot light in the instrument cluster.  You will need to get a different type of sending unit for the gauge.  They are readily available and relatively cheap from any parts store.  Just tell them the year and engine and specify that you need the sender for the gauge.  You can do some minor plumbing changes so that you have both the idiot light and the gauge operational.  Good luck.

[macdude443]

That's exactly what I needed to know.  I assume there is some sort of tee I can install?

[vangremlin]

Yes, that's what I did on mine.  i think I got the pieces I needed from a local NAPA store.

[BenM]

That's exactly what the factory did if you had an oil pressure gauge.


(image borrowed)

[macdude443]

Seems simple enough.  I stopped in at advanced today to pick up a pressure sensor and they had two.  One was for cars with a tach and one for cars without.  They looked about the same, but the electrical termination was slightly different.  One had a clip-looking thing and one had a standard thread with a nut.  Any idea which one to use?  My car had a tach but it never worked, so I can't remember if it was connected.  Also, I changed to an HEI and never used the "Tach" terminal, so how would that effect this sensor?  I'm a little lost.  I assume with the wrong sensor the gauge won't be accurate, if it works at all.

[BenM]

They're supposed to have the same resistance, the only difference should be the terminal, and it's probably related to the wiring harness installed for the different options packs as the rally gauges were a separate wiring harness.

Grab your voltmeter, it should read 60 ohms at 0 psi between the terminal and the case. That way you know it's the right part.

[greymarooneightytwo]

I put a mechanical oil pressure gauge in my car, there is literally a tube of oil going from a mechanical pressure sensor and then into my dash.

Works flawlessly.

[carnuck]

Unless the tube bursts and soaks your leg with boiling hot oil at 70 mph!

[greymarooneightytwo]

It's hard plastic and 60psi shouldn't provide enough to crack it...

I was actually more worried about it leaking at the gauge and getting oil on the carpet, I have enough leg hair to insulate myself from any semi-serious burns

[carnuck]

I thought I did too until I got first degree burns while cruising the highway! It popped the fitting off at the gauge because it was factory crimped too tight and heat/flexing/age broke it.

[vangremlin]

I thought I did too until I got first degree burns while cruising the highway! It popped the fitting off at the gauge because it was factory crimped too tight and heat/flexing/age broke it.

Dang Carnuck, you've taken some heavy hits when it comes to your encounters with cars!  You are one tough eagle lover!

[carnuck]

What can I say? I'm a survivor. I've been shot, stabbed, beaten, fallen from trees and a cliff, run over, had a car fall on me, 7 major accidents (including going through a windshield at 16 and rolling my Jtruck on my "driveway" and my racecar at 120 mph and run off the road on my uncle's Triumph Bonneville 750 turbo motorbike) but I'm too stubborn to give up.

Oh, and a nasty divorce too.

[vangremlin]

What can I say? I'm a survivor.

You definitely are, and you should take that as the ultimate compliment!