2007 4.0 V-6, Wonky oil pressure.

cbxer55 · Jan 25, 2020

Yesterday, driving to work, all the sudden my oil pressure "gauge" dropped to zero while idling. As soon as I revved it up, boom, back to normal. Every time I hit idle, it dropped to zero. Then returned to normal once the revs hit over 1000. On the way home from work, didn't happen. I suspect the sensor is going out. I just bought the car in November, it has near 116,000 now. Runs great. Well cared for by previous owner.

cbxer55 · Jan 27, 2020

Coming home from work, problem didn't reappear. Drove it Sunday, problem happened after about 30 minutes driving. Shut off, restarted, problem went away. For sure the sensor is bad.

But, I guess I'm wasting my time here.

David Young · Jan 27, 2020

You could get a bunch of B.S. thrown at you from people who can't answer your question. The problem is most people don't have a oil pressure gauge. I have the factory oil pressure gauge and I don't pay much attention to it. If you have an aftermarket oil pressure gauge, I would probably be changing the sensor or (and) the gauge.

Maybe you found out why the last owner sold it

cbxer55 · Jan 27, 2020

The factory gauge works for what it is. And oil pumps don't act like on/off switches. Oil pressure remains good until idle, where the needle just suddenly swings to zero, yet the engine runs and runs and runs. I let it sit in my garage yesterday when I came back from a Sunday drive, oil pressure zero. Engine idled for 10 minutes without fault. Shut it off, waited a minute, restarted it, oil pressure was back to normal. 100% certain it's just the stupid sending unit. I just need to find out where it is so I can see if I want to bother changing it. LOL!!

I've got two other Fords, a 98 3.0 Ranger and a 04 Lightning. I notice the temperature gauge on all three acts like a gauge, slowly going up, moving down a hair when the heater is turned on, etc. My Ranger, when the battery needed to be replaced twice, the gauge reflected it with the needle pointing considerably lower than it normally does. The boost gauge on my Lightning works correctly. So I don't consider the oil pressure gauge to be any different.

Also, it's not the previous owners fault. I bought the car November 15th. It only started doing this last Friday.

David Young · Jan 27, 2020

I hope your right. Many years ago I had a car that did the same thing your Mustang is doing. It did it for years. I sold it and the motor was still good, when the next person sold it. Then we don't know where the car ended up at after he sold it. It was still running great.

I have read, when the crankshaft bearings get worn out the oil pressure will drop, specially at idle. With the miles you have, the motor would have been abused and ran dry on oil for a while. I'm no mechanic. Good luck and let us know if it was the sensor.

cbxer55 · Jan 27, 2020

David Young said:
I hope your right. Many years ago I had a car that did the same thing your Mustang is doing. It did it for years. I sold it and the motor was still good, when the next person sold it. Then we don't know where the car ended up at after he sold it. It was still running great.

I have read, when the crankshaft bearings get worn out the oil pressure will drop, specially at idle. With the miles you have, the motor would have been abused and ran dry on oil for a while. I'm no mechanic. Good luck and let us know if it was the sensor.

Worn crank bearings may make the oil pressure low, but not a sudden drop from full to zero, like turning off a switch. And a sudden gain back to normal off idle, like turning on a switch.

Anyhow, I don't believe 115,000 is high. My Ranger is headed to 168,000 this week. Oil pressure is great on that 3.0. I've had it 20 years.

Like I said, once I find the sensor, I'll determine if I want to bother fixing it. I just changed the oil about 500 miles ago. So if I do fix it, it'll have to wait for the next oil change. ;-)

David Young · Jan 28, 2020

Are you using Fram oil filters? I hope not . If you do I've read, you have a 'good chance' of having oil pressure problems with Fram oil filters. People have fix by going with a different brand . Just wondering...…………...

cbxer55 · Jan 28, 2020

No, I don't use Fram oil filters on all my vehicles. See below for the exception. Tell the truth, don't know what kind it is. Just had it changed at the local Valvoline place a few weeks ago. Haven't bothered to look and see the brand name, it's white.

But, I do change the oil on my Ranger all the time and do use the Fram oil filters with the grippy end. Never had an issue with them on that vehicle. Been using them on that Ranger for 20 years.

cbxer55 · Feb 1, 2020

Drove it for over an hour yesterday, around my favorite stretch of curvy road, oil pressure never wavered. Drove it to work yesterday, took the long way in, same. Drove it home, took the long way, same result. So it's an intermittent problem. They're the worst kind.

Drove it a good 100 miles today, oil pressure good, even idling. So wtf?

cbxer55 · Feb 28, 2020

Update. A month later and the problem hasn''t re-occurred. Odds Bodkins. But still, I'm happy.

rbohm · Mar 4, 2020

replace teh sensor and clean the electrical conections, and give them a coat of dielectric grease. chances are the sensor is going bad, and coupled with a bad connection its giving the PCM faulty readings.

cbxer55 · Mar 4, 2020

rbohm said:
replace teh sensor and clean the electrical conections, and give them a coat of dielectric grease. chances are the sensor is going bad, and coupled with a bad connection its giving the PCM faulty readings.

I know this and would have already. But as I said, the problem has reoccurred. It happened that one day, and that one day only. If it happens again, I'll certainly look into it. I don't know where the oil pressure sensor is located. I had a really bad coolant leak at the heater hose where it attaches to the thermostat housing, stupid plastic parts. Anyhow, I had almost a gallon of coolant all over the engine by the time I got home and discovered it had happened. So I considered the possibility that some coolant got on the connections and was effing with them. But still found it odd the low oil pressure only happened after idling for about 30 seconds. And as soon as it was off idle, the oil pressure returned. So coolant on the connection is likely not the culprit. As you say, the sensor is possibly going bad or the connection is dirty.

cbxer55 · May 10, 2020

This problem happened on January 25th and has not happened again since. Weird. I wonder about something. Had a coolant leak where the heater hose attaches to the thermostat housing. Fixed that. But the motor got pretty soaked down by it, coolant everywhere. I wonder if some coolant got into the connector and made it act wonky?

2007 4.0 V-6, Wonky oil pressure.

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