93 K1500 oil pressure drops once warm

[mylesa]

I have a bit of a problem with oil pressure on my 93 K1500. When I start it up the oil pressure hovers around 30 but if I drive like a mile down the road or let it idle for a while the oil pressure drops to around 1-2 at idle. What could cause this?

 

[PlayingWithTBI]

When I start it up the oil pressure hovers around 30 but if I drive like a mile down the road or let it idle for a while the oil pressure drops to around 1-2 at idle. What could cause this?

A weak Oil Pump, worn Cam, Rod, or Main Bearings, plugged oil filter, a defective Oil Pressure Sender or Gauge, etc. Just a few things that come to mind. What weight oil are you using? You may get lucky by using a heavier oil and saving your money for a rebuild...

 

[RichLo]

First I would verify that its actually that low with an oil pressure tester gauge like in the link below. If it actually is that low, run 20w50 immediately. If it runs fine without knocks or anything they you have something wrong that TBI said above. You can replace your oil pump with a high volume pump to baby your engine along but its still tired and will eventually need to be replaced or rebuilt. How many miles are on the engine?

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[Keeper]

Can you hear valve tapping?

 

[Jeepwalker]

Try to find a gauge 0-100 (vs 0-150) ...if you can, to be able to get a somewhat more accruate low range reading. Gauges are least accurate at their extreme ranges. If you have a 0-30 or 0-60, it would be even better for single-digit readings, Link Here. Make sure the air is fully bled out. I just use a grease gun hose & fittings. Hopefully it's just a bad sensor...

One of my vehicles (full hot, on a hot day, in gear with foot on brake):

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[mylesa]

First I would verify that its actually that low with an oil pressure tester gauge like in the link below. If it actually is that low, run 20w50 immediately. If it runs fine without knocks or anything they you have something wrong that TBI said above. You can replace your oil pump with a high volume pump to baby your engine along but its still tired and will eventually need to be replaced or rebuilt. How many miles are on the engine?

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The engine has about 237k on it but the valves just got redone about 10k miles ago

 

[mylesa]

Can you hear valve tapping?

No the valves just got redone not too long ago

 

[GoToGuy]

It's normal for oil pressure to drop slightly as oil and metal parts come up to operating temperature. The service manual recommended is not less than 6 psi, at normal operation temperature idle. If not further diagnosis required. Yes it could be plugged oil filter, if you had weak pump. As the oil filter has a internal bypass and the filter boss has a plugged filter bypass it's doubtful that is the cause. If your truck is equipped with a radiator eng oil cooler, there is also a bypass in filter / cooler adapter if the cooler is plugged.
If there is NO lifter continuous tappet noise a mechanical oil pressure test gauge to confirm engine oil pump pressure. A very worn out engine can have problems with oil pressure when hot at idle. Whether you bleed the air out of the gauge hose or not, is not a problem. 30 psi, air, water, oil, hydrogen is still 30 psi. Your measurement is pound per square inch, not volume. The gauge test will tell you which plan to follow.
Good luck.

 

[Levman74]

Ha! I just started searching this issue and have the exact same issue. Mine likes to dip low after warming up and makes the CEL flutter on/off but I have no tapping or unusual noises and the engine runs strong.
This used to be an old horse truck and since I got it I have yet to change the oil(only did the filter) as it is just the farm truck.

 

[RichLo]

Old farm trucks need maintenance too. Oil's cheap and easy, why did you just do the filter??