Oil pressure fluctuating and then shows zero no pressure

Tiny
ZIA BALOCH
  • MEMBER
  • 2005 CHEVROLET TRAILBLAZER
  • 4.2L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 255,000 MILES
When I start my suv the oil pressure looks good, after some time near about two to three minutes later the oil pressure start fluctuating and then goes to zero.
When I switch off the car and start again it happens the same as I mentioned above.

Oil pressure and warning light both comes together, engine sound and behavior is found okay, no any abnormal sound.
can anyone help me regarding this issue?
Do you
have the same problem?
Yes
No
Monday, December 5th, 2016 AT 9:55 PM

7 Replies

Tiny
SATURNTECH9
  • EXPERT
You could just have a bad oil sending unit or a oil pressure issue. You could try just replacing the oil pressure sending unit. See if that clears up the oil pressure readings. Or measure the oil pressure itself with a oil pressure gauge test set.
Was this
answer
helpful?
Yes
No
+1
Monday, December 5th, 2016 AT 10:02 PM
Tiny
CARADIODOC
  • EXPERT
There are two things to look at. First of all, by far the most likely suspect is the oil pressure sending unit. Your mechanic can replace it with a temporary mechanical pressure gauge to verify the actual oil pressure is remaining okay. If it is, replace the sending unit, (sensor).

If the oil pressure really is dropping, at the mileage you listed, worn engine bearings can be expected, but your description does not really fit. Worn bearings will usually cause low oil pressure all the time, and once the oil warms up and becomes thinner, the pressure drops even more. That wont change when a hot engine is restarted. A better suspect in this case for low pressure is debris clogging the oil pickup screen. That debris can partially float away when the engine is stopped, so the pressure will be good again for a minute or two when the engine is restarted.
Was this
answer
helpful?
Yes
No
+1
Monday, December 5th, 2016 AT 10:06 PM
Tiny
ZIA BALOCH
  • MEMBER
Thanks for the guiding.
I am using 5W30 oil which is 10000 Km mileage, but I change the oil 3000 Km, after six or seven times changing oil in 3000 Km mileage I increased the frequency now I changing oil at 6000 Km mileage. When this happened I change the oil at 5000 Km mileage.
It is also recommended oil writen in fuel oil make up cap, manuals also.
I am adding little bit more, that I was on vacation for twenty two days and car handover to my friend he just start car for every day for two to three minutes in morning to avoiding the battery discharging. After returning from vacation it is happening again.

I will check the sensor test first, let s see what will be the result either its sensor fault of actual fuel oil pump issue.

Is there an any easy way to rectify the exact issue? Without removing oil sensor or going to contact with mechanic.
Was this
answer
helpful?
Yes
No
Monday, December 5th, 2016 AT 11:05 PM
Tiny
SATURNTECH9
  • EXPERT
No there would not be even if there was and it was just a bad sensor you would still have to remove and replace it to fix the problem.
Was this
answer
helpful?
Yes
No
Tuesday, December 6th, 2016 AT 7:51 AM
Tiny
ZIA BALOCH
  • MEMBER
Thanks all guys I fixed the problem which is oil sender unit. Now my car engine sound is back to normal.
Thanks again
Was this
answer
helpful?
Yes
No
Thursday, December 15th, 2016 AT 2:55 AM
Tiny
SATURNTECH9
  • EXPERT
That doesn't look like any oil pressure sending unit I have ever seen.
Was this
answer
helpful?
Yes
No
+1
Thursday, December 15th, 2016 AT 12:53 PM
Tiny
CARADIODOC
  • EXPERT
To me that looks like a switching device that stops or redirects oil flow, such as for variable camshaft timing. It sure doesn't look like a pressure switch or sensor.
Was this
answer
helpful?
Yes
No
Friday, December 16th, 2016 AT 1:16 PM

Please login or register to post a reply.

Recommended Guides