when its hot the light comes on but the guage works and is ok. it comes on at idle and goes off when i hit the gas. is the light right or the guage

 

bump

 

Put a manual gauge on it and find out. The fact that when RPM's are low (slow oil pump) you get a light ... I'd check it pretty quick.

Did you check your oil level?

 

I would take TMS Bill's advice. I think the gauge is no more than a showy idiot light. I recently did some engine work and while in the midst of it put a new Melling high volume pump in. My oil pressure before (on the dash gauge) sat at 12 0'clock idleand the next line over running. After I replaced the pump.... same thing. If I look at the gauge cruising @ 2k rpm's...... it sits at the line between 12 o'clock and 120. If I look at the gauge @ 5.6k........same thing. One way to tell whether you have sufficient oil pressure on a motor w/ hydraulic lifters is just simply to listen to it. If you have a stock valvetrain and your pressure drops low enoughyou will hear the racket.

 

On my 95 318 it would be fine but after it warmed up and you get on it and u get back to a stop the oil light will come on and it would be on 0 until i started going again

 

A lot of damage can happen before the lifters pump them selves put of oil.

Put a good mechanical gauge on it.

Too many things can affect the readings on electrical gauges. (voltage, ground, corroded connections, lose connections, feedback from other circuts through the ground wire not to mention resistor, capacitors and transistors depending on the mfg of the gauge.

 

I'll add to this. I have a 96 5.2L. Total miles is 234,000 but the motor was rebuilt with new oil pump at 186,000. So I am sitting at 50k since new pump. My truck is doign the same thing. Start up cold and you have 40 -45 psi. After 15 minutes, it is about 30 when moving and 20 - 22 at idle (per the factory gauge). The light will flicker at idle once the engine is hot. I cannot imagine a pump going bad in just 50k miles, but I guess anything is possible. I have replaced the sending unit and it did not change. A buddy from work has a mechanical gauge that will fit where the sending unit fits. I am going to try that first.
I thought about changing the oil and putting in 20w50.
A new aftermarket pump is only $35 or $85 for the high volume.

Do you think the heavier oil will make a difference or just "mask" the problem? The truck is not the primary driver but an around town truck. Is it worth the extra $50 for a high volume pump?

 

A heavier oil will better protect the motor ... not just mask the problem. I used 20w50 for many years (run 5w50 Syntec now). Try it out ... see what happens ... and yes ... the high volume pump is worth it ... but you should be able to find one cheaper than that.

 

Changed the oil today to 20w50. Holds a little better pressure (maybe 5 pounds).
The manual shows that the gauge and light both work off the pressure sensor. Whay does the light no come on when I dissconnect the sensor???? My light almost flickers like a float sloshing in the pan.

Anyhow, going to watch this for a little bit. I can see a new pump coming in the not to distant future. And at that point, since I think the rear main seal is leaking, I might as well replace that too.

 

i have the same problem and i have replaced the rear main, oil pump and sensor and the light still comes on, which is leading me to believe that it is something in the computer, my truck started acting up when my balancer went out the light would flicker and after i fixed that and replaced the timing chain it did it only when hot....well i drove it to south florida and on the way home blew the rear main, got the truck home fixed the rear main noticed pieces were missing from bearing cap but bearings still good replaced pump for good luck and then replaced the sensor..next day driving noticed my gauge actually moves and when truck is hot flickering light is still present...and that was last week