Oil Pressure Gauge doesn't work when cold.
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Oil Pressure Gauge doesn't work when cold.
I have a 2000 Excursion Limited with a V10. When the engine is cold, the oil pressure gauge reads below the bottom of the scale and the oil pressure idiot light is on.
The engine has normal oil pressure at that time, it just doesn't register. Once I start driving and go over a few bumps, the light goes out and the gauge jumps to the normal range and remains there until the truck sits and gets cold again.
Does anyone have a schematic to tell me which harness connectors I should clean and check? I assume it is not the sensor since it is cured by road bumps, not engine vibration.
Doug
The engine has normal oil pressure at that time, it just doesn't register. Once I start driving and go over a few bumps, the light goes out and the gauge jumps to the normal range and remains there until the truck sits and gets cold again.
Does anyone have a schematic to tell me which harness connectors I should clean and check? I assume it is not the sensor since it is cured by road bumps, not engine vibration.
Doug
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I would start by changing out the sending unit. I had a Dodge bus which does the same thing periodically. In its case, the sending unit has a copper ribbon "s" spring that comes off the top of the sensor diaphragm but just rubs against the contact button on the top of the sensor. (I took one apart to see what went wrong with it). It had gotten some moisture underneath the cover and had corroded at the contact point inside of the sensor. I'm not sure how the Ford sensors are made, but they're rather inexpensive and might be worth a try before digging into your electrical harness.
BJ Lexington, KY
BJ Lexington, KY
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Originally Posted by Monsta
Just curious Doug 
but how do you know that?
but how do you know that?Plus it instantly jumps up to normal, no gradual increase like on a normal startup.
But without connecting a pressure gauge, I guess I can't be sure.
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I guess you could measure the sending unit with an ohmeter first thing before and after startup. Then, down the road when it starts working, pull over and check it with an ohmeter again.
So, you'll have a value with the engine off.
You'll have a before and after reading with the engine on. If the sending unit is good, then these two readings should be the same right?
That would mean a loose connector.
If the before and after readings are different, then the before reading will probably equal the engine off reading and point to a bad sending unit.
Of course, this all sounds good on paper....so to speak
So, you'll have a value with the engine off.
You'll have a before and after reading with the engine on. If the sending unit is good, then these two readings should be the same right?
That would mean a loose connector.
If the before and after readings are different, then the before reading will probably equal the engine off reading and point to a bad sending unit.
Of course, this all sounds good on paper....so to speak
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Originally Posted by jesterdog
I guess you could measure the sending unit with an ohmeter first thing before and after startup. Then, down the road when it starts working, pull over and check it with an ohmeter again.
So, you'll have a value with the engine off.
You'll have a before and after reading with the engine on. If the sending unit is good, then these two readings should be the same right?
That would mean a loose connector.
If the before and after readings are different, then the before reading will probably equal the engine off reading and point to a bad sending unit.
Of course, this all sounds good on paper....so to speak
So, you'll have a value with the engine off.
You'll have a before and after reading with the engine on. If the sending unit is good, then these two readings should be the same right?
That would mean a loose connector.
If the before and after readings are different, then the before reading will probably equal the engine off reading and point to a bad sending unit.
Of course, this all sounds good on paper....so to speak
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I had an oil pressure sending unit go out on my 5.4 on my Expedition only it would start with pressure then no pressure then pressure the no. this went on for my 2 mile trip into town. took it the garage becaues i could get to the sending unit and had them change it out. Total cost about 65. If you search the Expedition pages there are several stories on this
2000 Excursion 6.8 V10 2x4
2000 Expedition 5.4 4x4
2000 Excursion 6.8 V10 2x4
2000 Expedition 5.4 4x4
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