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Oil light
#1
Hello,

      Have a 73 vert with 351 C 2V . Runs fine ... no issues.  Last night was out and noticed that at traffic light stopped in drive the oil light would flicker and come on solid or just flicker.  If I put the car in neutral which increased the rpm's the light would go out.  While driving the light would stay off.  I have a set of Bosch mechanical guages installed which show engine temp at 190 - 195 degrees.  Car has proper level of oil in it.  The OP guage shows app. 25-27 pounds at idle and and app. 50 pounds while driving.  On initial startup the pressure is at app. 75 pounds until engine warms up.  I believe the oil light is coming on do to a loose wire or maybe a bad oil sender, which is original to the car.  Any thoughts ?  Thanks
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#2
(09-07-2019, 04:38 PM)naa10104 Wrote: Hello,

      Have a 73 vert with 351 C 2V . Runs fine ... no issues.  Last night was out and noticed that at traffic light stopped in drive the oil light would flicker and come on solid or just flicker.  If I put the car in neutral which increased the rpm's the light would go out.  While driving the light would stay off.  I have a set of Bosch mechanical guages installed which show engine temp at 190 - 195 degrees.  Car has proper level of oil in it.  The OP guage shows app. 25-27 pounds at idle and and app. 50 pounds while driving.  On initial startup the pressure is at app. 75 pounds until engine warms up.  I believe the oil light is coming on do to a loose wire or maybe a bad oil sender, which is original to the car.  Any thoughts ?  Thanks

As a point of reference, my '73 H Code Vert with the original never rebuilt engine (50Kmi) idles at 45-50 psi.
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#3
25 psi is OK at idle, just not great. It's likely the oil pressure switch (sending unit). After 46 years the spring in the switch is probably tired. The idiot light comes on when the switch provides a ground, so if it's not the switch the wire to the switch is shorting out. Test it by pulling the wire off the switch and driving around. If the light comes on with it disconnected it is the wire shorting out.

You didn't say what oil you are using or how long it's been since the oil and filter were changed.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#4
(09-07-2019, 07:11 PM)Don C Wrote: 25 psi is OK at idle, just not great.  It's likely the oil pressure switch (sending unit). After 46 years the spring in the switch is probably tired. The idiot light comes on when the switch provides a ground, so if it's not the switch the wire to the switch is shorting out. Test it by pulling the wire off the switch and driving around. If the light comes on with it disconnected it is the wire shorting out.

You didn't say what oil you are using or how long it's been since the oil and filter were changed.
Hello,  thanks for the info.  My engine has 63k miles on it and has been rebuilt once before I owned it.  I change the oil once a year as I only put app. 1K miles on it.  New filter and oil, good grade 10W -30.
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#5
Because you live in a mild weather location you might consider using 15W-40 oil. It's a good grade of oil that covers a wide range of temperatures.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#6
Just fixed the exact same problem today. Oil light flickered on and off or stayed lit when idling. Went off in neutral or when I stepped on the gas. Oil level was fine. Just changed it using 20-50. Swapped the sensor and that fixed the problem.
Hope that works for you.

Mike

I'm just fixin' to get ready to start to get going.

I'm just fixin' to get ready to start to get going
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#7
(09-07-2019, 09:37 PM)mjseakan Wrote: Just fixed the exact same problem today. Oil light flickered on and off or stayed lit when idling. Went off in neutral or when I stepped on the gas. Oil level was fine. Just changed it using 20-50. Swapped the sensor and that fixed the problem.
Hope that works for you.

Mike

I'm just fixin' to get ready to start to get going.

thanks for all the advice, a few additional questions.  My main concern is do I have a bad oil pump ? one of the manuals I have says my motor should be making 45 - 75 lbs of OP when hot.  Mine is 25-27 at idle hot .... is that a problem ?  Could a thicker oil correct this ?  One of the comments was to test the OP with a reliable guage, is this to verify what my Bosch mechanical guage is telling me or would the test be more accurate ?  I am assuming that I would connect this gauge to the port where the current OP sender switch is located. I will check into the sender switch which probably needs to be replaced.  Wondering if a good starting point might be to install a new sender and change the oil to a thicker grade and see what that does to the OP and the flickering OP light.  Again thanks for the advice !!!
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#8
I prefer to do one thing at a time. If you go to a different oil and change the oil pressure switch at the same time you won't know which one fixed the idiot light problem. I would start with the switch and see if that solved the light problem and then go to the new oil and see what that does to your idle pressure.

The Bosch mechanical gauge should be good, but as has been said many times on our forum, new does not mean good. I have an SW gauge that I know is good that I use for testing.

You didn't say how many miles are on your engine. The most likely causes of dropping oil pressure are worn main bearings, worn rod bearings, worn camshaft bearings, worn lifter bores, worn oil pump, and stuck oil pump pressure relief valve. Oil pumps typically supply more pressure than needed, and the excess pressure is relieved through the pressure relief valve.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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#9
(09-08-2019, 08:32 AM)Don C Wrote: I prefer to do one thing at a time. If you go to a different oil and change the oil pressure switch at the same time you won't know which one fixed the idiot light problem. I would start with the switch and see if that solved the light problem and then go to the new oil and see what that does to your idle pressure.

The Bosch mechanical gauge should be good, but as has been said many times on our forum, new does not mean good. I have an SW gauge that I know is good that I use for testing.

You didn't say how many miles are on your engine. The most likely causes of dropping oil pressure are worn main bearings, worn rod bearings, worn camshaft bearings, worn lifter bores, worn oil pump, and stuck oil pump pressure relief valve. Oil pumps typically supply more pressure than needed, and the excess pressure is relieved through the pressure relief valve.

Hello,
 
I have owned the car for app. 5 years ... it has app. 63K on it.  My understanding is the engine was rebuilt in roughly 2013.  I can't tell you exactly what was done, but i do know some head work was completed and earlier in the 1980's or 90's a replacement block was installed. It runs well and seems strong.  I have never done a compression check on the engine ... I could do so if that is necessary.  To check the OP with a second guage does it get connected where the oil sender is located ?  Thanks
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#10
Yes, that is where I would check it. Where do you have the Bosch gauge connected, a tee at the sending unit?

That location is after the oil has passed through the engine, and gives a better idea of overall engine condition.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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