Need help with oil pressure light...sensor or pump?

[CharlesK]

My 2005 Navigator which I've owned since 2007 now has 250K miles on it. About 5 years ago (at 190K miles), the engine died while going 70mph on the freeway and I was told it was the timing chain failure. I assumed there was a catastrophic failure and decided to have a "remanufactured" (Triton 5.4L 3V) engine dropped in. TBH I don't know if the engine was remanufactured or not...for all I know the mechanic could have just "rebuilt" my old engine, although I kind of doubt it. I mention this history because I know engine age and miles is relevant. I can't say for sure how "old" this rebuilt engine is...but it did run completely problem-free for the last 60K miles (190K to 250K) since the rebuild.

Also, because oil maintenance is relevant, I admit the oil change interval may have slipped up to around 10k miles once or twice during this last 60K miles on the rebuilt. Recently, I started changing the oil myself and for the last oil change, I confess I skipped replacing the oil filter because of time issues (and not being able to find my oil wrench). Life happens and I forget to go back and change it, thus I drove another 5K miles without replacing the filter.

Anyway, I you can expect, the oil pressure light started coming on after the engine had warmed up and my speed slowed to an idle (whether at a stop light or a stop sign). The oil level was fine, so I assumed it was the oil filter I hadn't changed. I changed the oil and filter to see if it would help and it didn't...the light still comes on.

My question is...do you think its the sensor or the pump? I feel like it's not the sensor...because as the engine warms up more (and/or the more I drive it)...the light seems to come on sooner and sooner as I'm slowing down...in other words, it would only turn on when I was a complete stop for a few seconds...after it's hot it will come on before I even stop. To me, it seems the sensor might be fine and doing its job, being able to distinguish between hot v. cold and RPM's. It's almost like this warning light is trying to warn me even more.

So my question is...does anyone think this is the sensor and not the oil pump? I feel like it's the pump. Although I don't think the oil was too neglected, I'm curious if the oil pickup in the drain pan might be clogged and cause the low pressure. I don't know, the mechanic (who changed the oil) suggested to replace the sensor first for $225 and see if that fixes it. But I feel like that is a waste and that it is not the sensor as mentioned above.

Thoughts? (and prayers)

~Charles

 

[Action]

Diagnose before replacing parts.

If it were me, I would want to know exactly what the oil pressure was when the light came on.
If the pressure was high enough, may be the sensor is bad.
If the pressure is too low and you spent $225 to see the light coming on, seems like money spent poorly.

One other thing, the oil pump pushes oil through the engine. The last place the oil goes is the right cylinder head to the VVT solenoid. (Variable Valve Timing) The VVT solenoids on the top of the engine are used to advance and retard valve openings and do so in part with oil pressure. Low oil pressure impacts engine performance because there is not enough pressure to operate VVT solenoid as designed.

Diagnose the oil pressure first with a manual gauge.

The oil pressure switch is located just above and to the side of the oil filter. In many modular engines there is a second port with a plug

Action

 

[CharlesK]

Thanks Action, I had a feeling you would be the one responding. Quick question on your VVT comment. If the engine is currently running fine now even at idle...and there is no roughness even when the engine is hot and the oil light comes on at a stop,...do you think that maybe the oil pressure is okay and maybe it's the sensor?

Or can it explained that maybe there is just enough oil pressure to make the VVT work still...but still low enough that engine damage is being done? In other words, even though it appears the VVT's are working fine (because there is no roughness even at hot idle)...is it possible there is still damage being done to the engine internals...but just not enough damage done (yet) to affect the VVT's?

To put it another way...is it possible that the VVT's could still be working even under low pressure?

Or, conversely, can the pressure drop low enough to create internal engine damage without affecting VVT's? I'm assuming the answer will be yes...the VVT solenoids could still be working under low pressure and at the same time damage is still being done to the engine from this low pressure. Is it safe ti assume that once the internal engine damage reaches a certain point...the VVT's will ultimately then go too.

Thanks again!

 

[CharlesK]

Also, I just off the phone with another mechanic who actually (finally) suggested testing the pressure first to see what was going on. But he also said he has rarely ever seen an oil pump fail...almost never he said. I didn't ask him to elaborate on import engines vs. american (Triton 5.4 3V)...but he said it's usually the sensor or just the engine going bad in general. I told him about mine being rebuilt 60K miles ago...but I guess that might not mean anything...

______________________________

 

[CharlesK]

Just so I don't assume. This oil sensor solenoid is purely a gauge to signal the warning light...and it doesn't do anything in terms of regulating oil pressure. Like if it goes bad it doesn't make the pressure go up or down or cause wild fluctuations, right? If it was only the sensor that was bad... could I just put a piece of black tape on the dash to cover the light? Hypothetically of course...

 

[CharlesK]

Diagnose before replacing parts.

If it were me, I would want to know exactly what the oil pressure was when the light came on.
If the pressure was high enough, may be the sensor is bad.
If the pressure is too low and you spent $225 to see the light coming on, seems like money spent poorly.

One other thing, the oil pump pushes oil through the engine. The last place the oil goes is the right cylinder head to the VVT solenoid. (Variable Valve Timing) The VVT solenoids on the top of the engine are used to advance and retard valve openings and do so in part with oil pressure. Low oil pressure impacts engine performance because there is not enough pressure to operate VVT solenoid as designed.

Diagnose the oil pressure first with a manual gauge.

The oil pressure switch is located just above and to the side of the oil filter. In many modular engines there is a second port with a plug

Action

I see you have a 2006 Navi...is the oil sensor switch the one I see behind the oil filter...facing straight back towards the rear of the car? I should have taken a picture. It's about a 130-degree angle from the oil filter since the filter is at an angle pointing towards the driver's side downward a little (weird angle...at least on mine). Because it looks really easy to get to...like it could be taken off with a regular wrench.

 

[CharlesK]

Diagnose before replacing parts.

If it were me, I would want to know exactly what the oil pressure was when the light came on.
If the pressure was high enough, may be the sensor is bad.
If the pressure is too low and you spent $225 to see the light coming on, seems like money spent poorly.

One other thing, the oil pump pushes oil through the engine. The last place the oil goes is the right cylinder head to the VVT solenoid. (Variable Valve Timing) The VVT solenoids on the top of the engine are used to advance and retard valve openings and do so in part with oil pressure. Low oil pressure impacts engine performance because there is not enough pressure to operate VVT solenoid as designed.

Diagnose the oil pressure first with a manual gauge.

The oil pressure switch is located just above and to the side of the oil filter. In many modular engines there is a second port with a plug

Action

Is this the new part? because if so I'm pretty sure this is what I saw.

 

[Action]

Is this the new part? View attachment 20109because if so I'm pretty sure this is what I saw.

That is the new oil pressure switch for your modular engine. Should be very close to the oil filter.
Or oil filter mounting.

Action

______________________________

 

[Action]

This is a picture of a OE oil filter adapter with the pressure sensor.
Taken from an eBay listing that states it fits 2003 to 2008 Navigator with 5.4l engine.

The orientation of the picture may not be the same as on the engine.
(You would not want to wait for me to snap a pic of mine)

And there is an oil level sensor in the oil pan.

Action

 

[CharlesK]

This is a picture of a OE oil filter adapter with the pressure sensor.
Taken from an eBay listing that states it fits 2003 to 2008 Navigator with 5.4l engine.

The orientation of the picture may not be the same as on the engine.
(You would not want to wait for me to snap a pic of mine)

And there is an oil level sensor in the oil pan.

Action
View attachment 20115

Thanks, I feel like I can replace that myself. I have an appt. with a mechanic tomorrow to check the oil pressure with a pressure gauge and give me more data. He told me it was mostly likely not the sensor (based on my story of how the light comes on more quickly and stays on longer if I keep driving it...and not the oil pump (because he has almost never seen that)...and instead said it is usually the bearings going bad and losing tolerances. I guess I will know more tomorrow...

 

[Action]

I would want to know the pressures. Cold and hot. Idle speed and off idle speed.
On the adapter for my 06 5.4l there is an additional threaded tap.

Action