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Intermittent Oil Pressure Light When Car is Idling & AC is On


datdudejibril

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Hi all,

 

I have a 2013 Ford Edge that had an internal water pump break in October.  The mechanic changed the water pump, and flushed the engine several times, but the engine was still sluggish when driving after the fix.   We drove it for a month and the timing failed.  The mechanic didn't change the timing chain the first time and had to go back in the engine a month later to change it and the spark plugs..  After the second repair the car drove great however, we got an intermittent oil pressure warning light for a couple of days and it stopped until April.  (The mechanic said it may do that and we should do a couple of 1K mile oil changes to flush anything else out, which we did.)

 

In April the light started coming back on.  I took the car to the dealership but didn't tell them what happened in October and November.  They changed the oil pressure sensor which didn't solve the issue.  The "say" they checked the oil pump but I don't believe they did.  Finally, I explained what happened prior and the service rep immediately said that the bearings in the engine were failing and the engine would die sooner or later.  He said it could be 6 months or 2 years, but it will die.  But the engine sounded fine and the car drives perfectly, minus the off and on chiming.  I took the car to a Lincoln dealership and they couldn't even duplicate the issue, couldn't see any codes and also stated the car drove and sounded fine.  He stated it may be an electrical issue.  Ironically when we picked it up and went the carwash, the light came back on while the car was idling while it was being vacuumed.

I finally figured out the pattern to the intermittent alerts.  The low oil pressure doesn't alert on the highway, it only alerts when idling or during stop and go traffic.  Another thing I realized is that it is also correlated with the AC running.  We went to a "drive-through safari" that is an hour away from home. It was the first crank of the day and immediately got on the highway -- no warning.  But when we got to the safari and was waiting in line (of course with the AC on) the warning light came on and off in long intervals then shorter intervals as we sat there not moving with the AC on.  But I noticed that the short the chiming intervals became the WARMER the AC blew, to the point that I decided to roll down the windows and turn off the AC altogether because at that point there was only outside temp air coming from the vents.  And guess what?  Within a few minutes, the oil pressure warning stopped chiming altogether and stayed off.  15 min later I tried turning the AC back on and the AC blew cold and guess what?  The oil pressure warning starting coming back on and the AC increasing became warmer again.

So my conclusion is that something is overheating and when I'm on the highway the 70 mph air is keeping that part cool to the point the AC stays cool and there is no warning light. But in stop and go or idle traffic, the part is overheating, thus triggering the warning light and the AC to gradually stop cooling.  And that's why the Lincoln dealership couldn't get the light to come on. Even though they drove the car, they didn't get it hot enough and leaving it idling for the light to come on and that part to heat up.  Btw, the engine temp has always shown normal other when the water pump blew and the car was driven no more than 500 feet until the fix.  

 

What part could it be? Thanks in advance for everyone's help.  

Edited by datdudejibril
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Make sure both your cooling fans are coming on with the AC on and when the AC is off and its idling.

 

If the fans are coming on when they should and the temp gauge is normal, then it does look like the water pump failure and coolant in the oil has damaged the bearings.

 

Use a good synthetic oil and OEM oil filter and see if that improves things.

 

 

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sometimes you have to change the sensor a few times to get one that is cozy with the engine ?

 

in this case tho, you may need a calibration update of the PCM and/or IC (instrument cluster), sounds like a false alarm.  To confirm, check oil pressure at idle.  If the oil pump was damaged, that may be the actual root cause.  Have yet to see an oil pump damaged due to a WP failure that has not reached the chocolate milkshake point.

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Awesome!!  After reading your reply I jumped in the truck and drove it about five miles, then l let it sit with the AC on full blast for 15 min. 

 

1. The oil pressure warning did not come on.

2. I can confirm the driver side fan did not come on.

3. I noticed I could hear the AC compressor engaging every 30 seconds or so.

4. The engine temp gauge was normal.

 

Normally driving that length and letting is sit would have triggered the light, but its night time and about 78 degrees out and not daylight and 90 degrees.  Which leads to why the light came back on in April.  We're in Atlanta and the light started coming on regularly when my wife traveled to Pensacola FL where it was already 90 degrees out during that time. She doesn't drive at night so she would never have driven the truck during that time to notice the difference. 

So does all of this mean that the non-working driverside fan is causing an AC component to overheat which then is triggering the oil pressor sensor?  Because, I verified today that when the engine is hot and the AC is not running, the oil pressor light is not triggered. 

Btw, I only use synthetic, not sure about the OEM oil filter. 

 

 

1 hour ago, 1004ron said:

Make sure both your cooling fans are coming on with the AC on and when the AC is off and its idling.

 

If the fans are coming on when they should and the temp gauge is normal, then it does look like the water pump failure and coolant in the oil has damaged the bearings.

 

Use a good synthetic oil and OEM oil filter and see if that improves things.

 

 

 

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I read this in other thread as well. But after the confirming running the AC is directly affecting the oil pressure warning complicated things.  Water did get in the oil.  But after confirming the driver fan is not working, could the oil pump be overheating?  Is the oil pump and AC compressor on the same belt? 

 

1 hour ago, WWWPerfA_ZN0W said:

sometimes you have to change the sensor a few times to get one that is cozy with the engine ?

  

in this case tho, you may need a calibration update of the PCM and/or IC (instrument cluster), sounds like a false alarm.  To confirm, check oil pressure at idle.  If the oil pump was damaged, that may be the actual root cause.  Have yet to see an oil pump damaged due to a WP failure that has not reached the chocolate milkshake point.

 

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22 hours ago, 1004ron said:

 

Don't understand what you mean by that - see thread title  :  "Intermiten Oil Pressure Light"

 

I meant "Intermittent".  But when I tested after your initial reply the warning light did not come on. I believe because it was at night and the outside temp wasn't as hot, even though I drove for 5 miles and left the truck running for 15 mins. 

 

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4 minutes ago, datdudejibril said:

 

I meant "Intermittent".  But when I tested after your initial reply the warning light did not come on. I believe because it was at night and the outside temp wasn't as hot, even though I drove for 5 miles and left the truck running for 15 mins. 

 

I wasn't getting at the typo, just the comment that he low pressure warning light didn't come on, but the title indicates that it did, and even if it only comes on when the ambient temperature is high, that's still a problem.

 

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7 hours ago, 1004ron said:

I wasn't getting at the typo, just the comment that he low pressure warning light didn't come on, but the title indicates that it did, and even if it only comes on when the ambient temperature is high, that's still a problem.

 

 

It chimes and then stops (meaning the alert disappears altogether) then chimes again.  But while at the drive-through safari, as the AC blew, the warmer the ac became and the more frequent the chimes occurred.  When I turned the AC off, the chiming stopped completely.   Then when I turned it back on, the AC blew cold again, but the chiming started again, and the same cycle happened over again.  AC air became warmer and chiming became more frequent.   When I tested last night after your message the chiming didn't come on at all even though I had the AC on, drove 5 miles and left theft the truck running for about 15 mins.  Also, the driver fan was definitely not running at all.    Based on your initial suggestion of the fan, I'm now taking it back to the dealer with this additional info.  

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On 8/22/2020 at 11:53 PM, datdudejibril said:

2. I can confirm the driver side fan did not come on.

First and foremost, either the driver side fan is failed or the fan controller. This will cause the engine to overheat when idling and going slow (at highway speeds the air flow through the heat exchanger is sufficient).

An overheating engine will run rough. 

 

This happened to me couple of years ago. Had the local Ford garage change the fan assembly (both fans and controller are mounted to a frame as an assembly). If you do it yourself, don't think of using anything other than Motorcraft assembly (aftermarket assys have been poor at best).

 

Should solve several problems. I'd also recommend turning off the AC when idling and at slow speeds until its repaired. This is really hard on an engine so don't put it off too much longer.

 

Als recommend doing an oil change afterwards. Oil may have cooked if it got too hot. Synthetic has limits too.

Edited by enigma-2
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