Oil pressure

chevrolet
3500

#1

When I first start the truck the oil pressure is normal. But after plowing snow for awhile when the engine gets warmed up the pressure drops down to nothing. When the engine is idleing it is at o pressure. When I step on the gas the needle goes up. Could it be a faulty oil pump?



Thank- you


#2

You need 10psi for every 1000 RPM…What weight oil are you using? How many miles on the engine??


#3

I’m using 10W/30 oil. Not sure about the miles - but well over 100,000. It doesn’t burn that much oil in between oil changes though.


#4

Have the pressure checked with a mechanical gauge when the engine is warmed up. If it’s reading different than your dash gauge, try replacing the sensor. On an engine this old the problem is likely worn engine bearings and not the oil pump. So basically you will eventually need to rebuild the engine if the problem worsens–eg. you no longer get a decent amount of oil pressure at any speed. The engine will probably suffer the most while idling—there may not be enough pressure any more at low RPMs to force oil into the top half of the engine. (the valve train)


#5

What is your cash situtation, how much do you rely on this truck? If you use it only 2 or 3 thousand miles a year, then go to a heavy weight oil. If you use it daily, you may be able to get by with dropping the pan, and putting in new bearings, as this is a classic sign of bearing wear. Use plastic gauge to test the new bearing fit, and check the journals for scoring. If the journals are badly scored you will need to have the crank turned, and once you go that far, you might as well put in a re-built engine. As an additional test of engine wear, what condition are your plugs in? Oil fouling of plugs indicates bad valve seals and or bad rings. How much oil does it burn? another indication of wear is high oil consumption. good luck with your truck woodwork.


#6

Yes it could be a worn oil pump and if you don’t fix it your engine will lock up.

It could also be a large about of fuel diluting the oil. It could also be a plugged oil filter. Change the oil and filter and if the pressure does not go up right away, check it with an oil pressure gauge to confirm the dash reading. If it’s still low, you may need an oil pump. Or your engine could simply be so worn that you need a heavier oil, like a 20W50.