Faulty oil pressure readings from gauge

CHET SANDHU

MEMBER
2005 NISSAN XTERRA
4.0L
6 CYL
4WD
AUTOMATIC
130,000 MILES

Hi guys, Please help.

Since I got this vehicle I have been having problems with the oil pressure gauge readings.

Three months ago I got a new oil pump, timing chain kit installed and new water pump.

After about one month of this job I started to see pulsation in the oil gauge reading. Took it in and apparently the rear timing cover oil gallery gasket was leaking as the mechanic used RTV which was recommended by the dealer. This time I ordered the gaskets and got everything out back to gather.

For about two weeks everything was good and sound. Few days ago it got cold out here in Canada and the oil pressure needle went to high reading. After warm up it would come to the middle and stay there until I floored the throttle and it would go to high again. But now form the past three days the pressure is responsive to RPM. Oil pressure needle get very low when at idle.

When I got it fixed at first the needle would be right in the middle when my foot was on the gas. Now it just kind of just pulsates with he RPM kind of like when the gaskets were leaking,

I have done a lot of reading and seen that it could be the sending unit or the oil pressure sensor. I would love some input on what could be wrong. Please help! I have spent like $2,000.00 already. The gaskets I out in are CPZ performance sold gaskets.

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi and thanks for using 2CarPros.

There is a good chance it is the sending unit. The sensor is crimped together (plastic to metal) and over time, that crimp weakens. Often times, the sensor will start leaking. The leak allows pressure to partially bypass the actual sensor. Thus, you can show low readings or unsteady readings.

Keep in mind, it is normal for oil pressure to change with RPM's. The faster the engine turns, the more pressure is produced.

Check the sensor and its wiring first. I attached a picture of its location. It is on the right side of the engine (passenger side) in the upper oil pan. See picture 1 See if there are any leaks from it.

Now, there is one other thing that does not happen often, but behind the oil cooler (where the oil filter is mounted) there is a pressure relief valve. It is small and is pressed in. I have seen them fall out when the cooler is removed. Since you had engine work done with the oil pump, there is a chance it fell out. Actually, I have seen them fall out when the cooler is removed. In the second picture, locate part number 6.

You may want to check that if nothing else proves bad. You may also want to rent a mechanical oil pressure switch which will basically screw into the same location as the electric oil pressure switch. By using a mechanical gauge, you can be more confident if the pressure readings.

One last thing, make sure you are using the correct oil viscosity and a quality oil filter. I have even see inexpensive oil filters cause pressure issues.

I have had many of these engines apart. So, if you have questions, let me know.

Take care,
Joe

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Tuesday, November 27th, 2018 AT 9:26 PM

CHET SANDHU

MEMBER
3 POSTS

Thank you Joe,

I will start with the sensor and then pull the oil pan to see if the sending unit is clogged. If on of those is the issue easy fix. If not then I will look into the valve and see if that is the problem. Thank you so much for your help. I will keep you updated once I get my hands dirty over the weekend.

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Wednesday, November 28th, 2018 AT 12:11 AM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Welcome back.

Honestly, you should not have to pull the pan. You can remove the sensor. Much easier.

Let me know and good luck.

Take care,
Joe

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Wednesday, November 28th, 2018 AT 1:35 PM

CHET SANDHU

MEMBER
3 POSTS

So the truck is going to the shop tomorrow morning and lets see what happens. In the mean time I made two videos one is for the pressure issue and the second is a weird noise. Any input would be great.

I will keep you updated after tomorrow.

https://www.youtube.com/watch?v=C8JgDuu-hN4
This is the video of the weird high pitch sound. I was told it is valve cover sound? Just looking for more input. Also this sound will start when engine is warmed.

https://www.youtube.com/watch?v=m9KkvftF-h4
This is the clip of the oil pressure gauge. After two to four minutes warm up it will start fluctuating just a little above low to medium depending of rmp and throttle implication.

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Thursday, November 29th, 2018 AT 10:46 PM

JACOBANDNICKOLAS

MECHANIC
108,269 POSTS

Hi:

I cannot identify a noise from the video. As far as the oil pressure gauge, I bet there is a short to power. With the key on/engine off, the gauge was already centered. It should be at 0.

Let me know what you find.

Joe