Oil pressure idiot light stays on

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'74 Sport

'74 Sport

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All throughout the break-in period and tuning on an indoor dyno, the 360 we built for my son's car maintained a solid 60-70 lbs oil pressure. Engine is now in the car and running great; however, the dash light stays constantly on. Any ideas why this is happening? I suppose I could tie-in a pressure gauge and see for sure what it is, but I am wary of a small tube bringing hot oil into the cabin area. Anyone using an electric gauge they would recommend?
 
Autometer is one. Have you tried unhooking the wire? Does the light go out? Bad sender? WRONG sender? "Light" sender is small, "gauge" sender is a large can

Last I knew, NAPA sold universal COPPER guage line kits. Oil pressure was done this way for many, many, many, ........many..........years
 
Ya. I'd guess that you had a pressure gauge sending unit on it when you read the 60-70 pounds pressure on the dyno. You'll want to use your old one instead.
 
Not a thing wrong with nylon oil line. It's been run for decades with no issues. Keep it away from sharp edges and heat.....duhhhhh.

I recommend against copper line. It does not have any give as the engine moves and has been known to break. JMO, as I have seen it.

A plumbed in pressure gauge is best.
 
You can Tee a gauge into the back of the block, under the dizzy. I know its tight but doable. I also know you cant check it from the drivers seat. But I almost never look at the gauge anyway.By the time it tells me anything, its gonna be too late. They are good for trending over time tho.But so would an underhood one be.
 
RustyRatRod said:
Not a thing wrong with nylon oil line. It's been run for decades with no issues. Keep it away from sharp edges and heat.....duhhhhh.

I recommend against copper line. It does not have any give as the engine moves and has been known to break. JMO, as I have seen it.

A plumbed in pressure gauge is best.
Click to expand...


Yes, copper lines work harden and eventually break/fracture with vibration, I would not recommend using a copper line for oil pressure...

I use the nylon tubing, and keep a spare replacement tubing kit in the glove box JIC.
 
I use a cheap Chinese one I got off ebay
(im planning on redoing the dash with all gooder gauges at some point anyway)
I think I paid something like 26 bucks for it


seems to do allright, and it is all electronic so no tubes of hot oil going into the cabin
 
My F250 had a manual gauge plumed in with the factory gauge when I got it. I drove it long enough to see that it had 60 PSI hot running down the road and 30 plus idling and the factory gauge seemed to correspond, so I disconnected the manual gauge. I have not gotten around to removing it yet, but the factory one works great. No need to supplement if everything is fine.

If you would like this gauge, I will go ahead and remove it gauge, line, fitting and all and send it to you. You will need to adapt it into your existing sending unit but that is easy with the correct brass fittings found at any good hardware store.

PM me your address and I will send it. It will give me a reason to get off my butt and go ahead and remove it. lol
 
It won't go off? It must sense an idiot :D...lol (jk)

I use nylon all the time. You can buy small grommets to pass it through the sheetmetal, and unless you melt it or cut it, I've never had one fail or burst on it's own. That's running them since 1986. Copper will work, but you will also notice a ton of movement in the needle as the tubing tends to remove the myriad of pulses that the oiling system normally experiences. I've never seen copper break either, but it never came in the gage pkg so I used what was provided.
 
i would buy a new oil pressure switch that was intended for a Light. Bet it fixes the problem.
 
You're all winners!!
Looks like the problem might be that when the engine was pulled from my folks' old Dodge Maxivan and sent off to be rebuilt, a new sender (large can style) was installed for a gauge, not a dash light. We'll know soon enough when it gets replaced this weekend. :eek:ops:

As for the pressure gauge, it really isn't the fact that plastic tubing is being used. It's just that when I installed a similar gauge on the car's original slant six, it wasn't long before oil began slowly seeping behind the gauge's glass on the dial. Fortunately, it was only there for the initial setup of the newly rebuilt engine and got removed fairly soon. Thinking back on it, I would have to admit it was probably a fairly cheap one acquired at a local parts store.

Thanks for all the input.
 
AJ/FormS said:
You can Tee a gauge into the back of the block, under the dizzy. I know its tight but doable. I also know you cant check it from the drivers seat. But I almost never look at the gauge anyway.By the time it tells me anything, its gonna be too late. They are good for trending over time tho.But so would an underhood one be.
Click to expand...

I had a Ford Falcon that I wired in a seat belt buzzer out of a wrecking yard car to the idiot light sensor and also had a gauge.
That way you knew instantly if there was pressure loss and shut it down before anything bad happened. :)
Never needed to, but fair warning was there in case.
 
Copper's work hardening trait is easily dealt with. Put a few loops or coils in the tube. The larger, the better. This spreads the 'work' out over a long distance and radically decreases the hardening at any given point. GM did this for decades on their mechanical oil pressure gauges in their pick-ups. Never heard of one of those failing, ever. I have seen and heard of the plastic lines failing. No thanks.

If you really want robust, break out the wallet for some -2 AN/JIC hose & fittings.
 
I've never had a problem with plastic lines. It's all about the routing and install. I've had the same line in my Jeep for 10 yrs now. It's been a daily driver, rock crawler and mud swimmer. I may just be lucky.......but that would be a first......Murphy and I share the same law...
 
Make sure that there are no idiots near when you run the engine, that could make the light go on....

An idiot light will tell you if there is an idiot around...
 
What if they invent a better idiot? Does the light still work?
 
i run a oil pressure gauge because i like knowing what it is doing and if there is a problem i know right away. i also been running the oil line from motor to pressure gauge for many years with never an issue one time

when i first changed out my motor my buddy pinched the sender wire and grounded it out and the light stayed on all the time and then the light went out the second i found the problem and un pinched it
 
idiot light..hmmm.
when your gauge indicates lo oil pressure you may miss it.
..I guarantee you won't miss the red light!

4 out 3 people have problems with fractions.
 
I kind of like the idea of the seat belt buzzer wired in for instant notification. You surely won't miss that.
 
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