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Oil light is on

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2wrench

2wrench

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My oil light comes on when I start the car, but the oil
pressure is still pretty good; 50lbs., but I have seen it
heretofore go to 75lbs. Seems I've seen it come on before
and then go off if rpm's are raised a bit.

I suppose I should be concerned, eh?
 
There is a relationship (electrically speaking) between the oil pressure switch and the PDWA. Make sure you have the terminals on the oil pressure switch connected to the proper wires and you have a good connection there and at the PDWA.
If that's as good as it's supposed to be then, yes, I guess the next step would be to suspect the switch itself.
 
Here's the schematic for the three prong.
 

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Thanks, Paul. I transferred the wires per this schematic. Seemed to help
at first; then, back to the same old stuff.

Actually, seems okay at first, then not so hot after warm-up.

Another possibility: Oil pressure relief valve. What do you think?
Machine shop said when I picked up my car engine parts re the oil
pressure relief valve: "I set it (relief valve,) and don't touch it. Just
install it."

Wonder if the setting ain't so hot and once it warms up, the valve starts
to blow off some of the pressure?
 
You said the gauge shows 50 psi; while the switch should operate at under 10 psi. Gotta be either the switch, or some other wiring problem.

I've seen switches act that. Light goes off when you first start the engine, then later comes back on and will go off again if you rev it up. Generally means the switch is leaking oil internally, through the diaphragm but not through the plastic housing. Which presents at least the possibility that the plastic housing will fail suddenly and start dumping oil on the ground.

I'd replace it sooner rather than later.
 
Get a new switch, now that the wires are correct.

What setting is he (your machinist) talking about for the pressure relief valve? You just install it. There is no adjustment that I'm aware of.
 
Hmmm. Paul, I really don't know. Just parroting back what I heard him
say. Probably best to just replace it. I mean, these parts have only lasted,
what, 34 years?

Think I'll just replace and see what happens. These parts are probably not
that expensive.
 
There is a kit from TRF and probably the others, that is the big bolt, the spring and a washer. I put a new one in my engine when I had it rebuilt. Cheap insurance, IMHO.
 
Worth noting, perhaps, that if you don't plan to use the anti-runon solenoid; you can use the less expensive single terminal oil pressure switch. About $5 instead of $20 for the 3-prong. Just tape off the white/brown wire and leave the black disconnected (the single terminal switch grounds through the mounting).
 
TR3driver said:
Worth noting, perhaps, that if you don't plan to use the anti-runon solenoid; you can use the less expensive single terminal oil pressure switch. About $5 instead of $20 for the 3-prong. Just tape off the white/brown wire and leave the black disconnected (the single terminal switch grounds through the mounting).
Click to expand...

Randall, while on the subject, I did hook up my anti-runon solenoid that had been
disconnected by the previous owner. Tell me more about this part. What is its function?
You make it sound rather optional. Why have it?
 
It's purpose is to make sure the engine stops running when you turn off the key. You can accomplish the same thing by letting out the clutch with your foot on the brake.

I'm not saying you <span style="font-weight: bold">should </span>remove or disconnect it, but many people chose to do so.
 
Connect the anti run on and shut the car down the way it was designed to be shut down. If you have the engine set up properly, you won't need to stall it to stop it from running. You've come this far doing things correctly, keep it going.
 
2wrench, the ARV is a solenoid (electromagmetic) valve. It only opens when you turn the ignition key to off. Then the valve gate opens allowing the vacuum present in the intake manifold at the brake servo banjo fitting to be transfered thru the ARV, the Carbon Canister and finally the float chamber vents on the upper front left side of your carbs. This vacuum prevents gas from being drawn up the jets as the engine is shutting down and prevents Run-on.
The valve returns to the closed position when the oil pressure drops and the circuit is broken by the oil pressure switch.
If you'd like to read an "official explanation" you'll find it in the Haynes Manual, Chapter 13/ Supplement. Look under the description of the "Evaporative emission control system" paragraphs 10 thru 12.
 
And it doesn't matter which of the two wires goes where on the switch.
 
I'll disagree ... if you swap any two wires on the switch, either the ARS or the oil pressure light will not work properly.
 
2wrench Randall said:
<span style="color: #000099">Dennis, my car does not have an anti-runon device. My car used to runon
when I turned off the key and DPO Pedro told me the same thing.
"Stall the car in gear." I always felt that concept was lame.

I found that with proper timing, properly adjusted carbs and high test
gasoline- my car engine stops instantly when I shut it down.

Just my two cents worth.

d</span>
Click to expand...
 
The switch is cheap and easy to replace. I once had one go bad and the center parts actually blew out of the metal casing. Transformed the engine to a solid mass of metal. The good thing was it was not a Triumph, the bad thing was that it was a really nice '65 Corvair.
Shirley called and said she did not know what was wrong but that she was passing a car and could not figure why the car kept loosing power.

For the run-on try lowering the idle some. Especially if you notice that the run-on does not always happen if you blip the throttle before turning off the ignition. It might be running just fast enough to be just out of the idle stage of the carbs.
 
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