Low oil pressure warning

[alcyon]

I had a low oil pressure sensor failure last year and replaced the sensor that screws into the lower block. However, lately I noticed something odd.
In the mornings the warning comes on for 1 second ,as soon as the car starts it goes away, which is normal.
After say a 1hr drive, I stop for a few minutes, then restart the car, the warning doesn't even light up.
Is this normal because there is residual pressure in the block..or is the warning supposed to light up every time right before the engine turns over ?

 

[spasm3]

What vehicle? i would expect it to be lit before you turn the engine over, as there is no oil pressure before you crank or run the engine.

 

[alcyon]

basically its a 1986 dodge(Mitsubishi) colt.
I was wondering perhaps the sensor itself has problems or the wiring, because sometimes even when the engine is cold the warning doesn't come on when I turn they key to positions right before it starts. At this position, the handbrake, battery and low oil pressure warning should light up.

 

[Clevy]

From a cold stsrt is it possible the oil pump is allowing oil to completely drain from the pick up tube. That would explain no pressure at stsrt up for a second.
When re-starting hot the pick up tube is still full,thus no oil pressure light.

Just spitballing.

 

[javacontour]

What oil and what temperatures when you start the car?

 

[alcyon]

ambient temp is about 27 C in the mornings. Temps will get to 36C at the peak of the day, sometimes 38C.

Oil is shell helix ultra 5W-40 which has about 3000 km on it.

 

[Nick1994]

Change the sensor again and check the wiring.

My grandpas Jeep didn't have the oil light come on the dash when you turn the key for years, finally realized the wire was broken off the sensor. Works good now.

 

[TFB1]

Originally Posted By: Nick1994
Change the sensor again and check the wiring.

My grandpas Jeep didn't have the oil light come on the dash when you turn the key for years, finally realized the wire was broken off the sensor. Works good now.

Agreed, if it doesn't light anytime the engine is shut down the sensor or maybe wiring is at fault...

 

[Lubener]

Replace the sender or oil pressure switch

 

[HangFire]

The sensor is sticking. Replace it.

Welcome to the world of sub-par quality replacement parts. You may want to pony up for the OEM this time.

 

[javacontour]

I tend to agree, sensor is suspect. I don't know what they cost in your corner of the world. They are pretty inexpensive here.

 

[alcyon]

Thanks for the input guys, love the humour Hangfire...that reminds me of that early 90s B movie with Jan Micheal Vincent.
Yeah I got a new sensor, cost about 3 bucks. The OEM is impossible to get these days. However the sensor / switch is supposedly made in Japan. Will be switching it out later today, pun very much intended.