Oil Pressure Light

[Kim Reeves]

Hello! Looking for some guidance.
Oil Pressure (Green) light has started coming on after driving 1-2 minutes. No other performance issues but...the oil temp gauge has never worked, had it calibrated by North Hollywood but recently it would spring to the max and go back down when i start the car - around the same time the oil pressure light started to come on.
I have ordered a new pressure valve and sender from Stoddard. But if anyone has advice, that would be great.
Jon
64-356SC Coupe

[George Hussey]

one quickie is to tape off the oil pressure switch lead and drive the car again. If the light still comes on, there is a wire grounding problem

[John Brooks]

The oil pressure and temp gauges have power applied to the Gauge, and seek a ground at the engine. It sounds like you have the wires swapped at the engine side. Pull the wire off the pressure switch, turn on the key You will see the red generator light, Then touch the end of the wire to the case or some bare metal. See if the gauge moves or the light comes on. You should get a green light, if the temp gauge pegs, swap the wires between the temp sensor and the pressure switch.

[Jules Dielen]

Can't really be wiring if it only happens after 2 minutes with a warmed up engine I asume. I would try some higher viscosity oil first, then swapping out the sensor and then a mechanical pressure gauge to see what is actually going on.

[John Brooks]

I think its similar to a wiring problem I ran into a couple months a go. The oil light was finding a ground in the temp sensor when the oil heated up. The pressure switch was open with pressure, but the temp sensor wire and oil light were shorted together.

“ would spring to the max and go back down when i start the car - around the same time the oil pressure light started to come on”. It’s wired backwards, the oil pressure wire is on the temp probe. swap the wires aroound

[Wes Bender]

Oil pressure being as critical as it is, I would definitely check it with a mechanical gauge. Easy to put one together that connects to the bypass oil filter line.

[Jim Liberty]

I hate "Idiot" lights. In my driver cars I install this: ............Jim.

[Kim Reeves]

Thank you all for the responses - parts are ordered and i will try the simple wiring tests first and keep you posted!

[David Nicholls]

Dear Kim

Sorry to hear about your problem.
I’ve included a photo to show you what can happen.
In this case the owner allowed the engine to run for some minutes after the Green Oil Pressure Warning Light came on.
The Tang for the Oil Pump had broken, hence no lubrication.
Damage done to the No3 Big End Bearings as shown, shrapnel everywhere in the Crankcase, No3 Conrod overheated and No 1 Main Bearing about to seize.
Repairs needed, Crankshaft line bore, Crankshaft Main and Conrod Journals ground to 1st under,.
Parts needed, new Oil Pump Gear with Tang, a Conrod, Main Bearings, Big End Bearings, gaskets.
Lots of $s and time.
The tragedy is that this was a nice engine that hadn’t been machined or damaged before.

I’m sure that you’ll get yours going again, let’s know how you fixed it.
Regards
David
PS Extra cockpit gauges are cosmetic value only, unless they are calibrated.

[Wes Bender]

Knowing Jim, those gauges are not just cosmetic, and are a damn sight better than the idiot lights.

[David Jones]

As long as you pay attention to the gauges then you can make a positive argument for their worth. On the other hand when I was busy in the cockpit of the race car an idiot light could be a good attention getter so having both would be the preferred approach but seeing oil pressure or any other parameter get closer to allowable limits will give a margin of safety over the moment the idiot light comes on. Airplanes use gauges for a very good reason.
I would hazard a guess however that most drivers today if quizzed, probably could not tell you what most of the lights and icons on their dashboards actually signify.

[Martin Benade]

Gauges are also useful even if not accurately calibrated to let you see deviations from normal readings.

[Kim Reeves]

@john Brooks - thank you!! that was it! after doing some continuity tests - that was it - and now my oil temp works as well! bonus! Thank you.

[John Brooks]

Very good description of the problem makes it easy. Plus I just fixed a similar one a couple months ago.. Was it at the motor or under the dash??

[Kim Reeves]

it was at the engine - must have been from the restoration. So technically its never worked - the oil temp has never worked till now!