What causes no oil pressure at idle?

[gt1009]

I've been having some issues with my truck's ignition lately, and now there has been a bigger issue where my oil pressure drops down to zero at idle. It acts normal most of the time sitting at about 10 psi at idle, which seems a bit low. but this weekend I took it on about a 50 mile trip, and after a few miles at highway speeds the check engine light came on. I didn't think much of it, but when I came to a stoplight the oil pressure went to zero, then the needle started waving back and forth. If I gave it a tiny bit of gas it would jump back up to about 10 psi. I'm wondering if my oil pump is weak, or if I'm having problems with my distributor, which would tell me why the truck seems to miss a cylinder under hard acceleration too. I checked the oil and it's full, so I'm wondering if I just have a faulty gauge or a bigger problem. Anything else I should check?

 

[British Slave]

Sending unit may be funky, but it sounds like it is OK. It is easy to check. Could be gauge but it too sounds normal. Other problems could be oil pump, excessive clearance in the cambearings, main bearings, etc. Put a gauge on the engine and find out what you have.

 

[imiceman44]

If you didn't have the engine light come on, I would have thought maybe the sender or the guage is faulty, but the engine light for low oil is a different sensor so it shows that you DO have a problem, my guess is worn bearings or pump.

I've been having some issues with my truck's ignition lately, and now there has been a bigger issue where my oil pressure drops down to zero at idle. It acts normal most of the time sitting at about 10 psi at idle, which seems a bit low. but this weekend I took it on about a 50 mile trip, and after a few miles at highway speeds the check engine light came on. I didn't think much of it, but when I came to a stoplight the oil pressure went to zero, then the needle started waving back and forth. If I gave it a tiny bit of gas it would jump back up to about 10 psi. I'm wondering if my oil pump is weak, or if I'm having problems with my distributor, which would tell me why the truck seems to miss a cylinder under hard acceleration too. I checked the oil and it's full, so I'm wondering if I just have a faulty gauge or a bigger problem. Anything else I should check?

 

[diesel4me]

Could be the pump is getting weak,the bearings have excessive clearances (usually you'll hear a woodpecker type clatter upon a cold start when a bearing is loose,until the oil pressure reaches it and fills in the gap)--or it could be cam bearings that have excess clearance bleeding off the pressure.............................................................................................Something I've seen many later model car engines do similar to your symptoms,is to start off cold with normal "good" oil pressure--then it gradually drops as the engine gets warmer,until at idle hot,it may not have enough oil pressure to keep the oil light from flickering,or staying lit....the culprit was a clogged up oil pump screen!--sometimes oil can lose its viscosity when hot too,some brands tend to do it more than others do........................................................................................................................................................................................................I always thought that a clogged screen, that was sludged up, would starve for oil when cold more so than hot,and allow more oil to pass thru once it warms up and thins out more,but evidently not--the sludge settles overnight to the bottom of the oilpan,then gets sucked up after the oil warms up and circulates...seen this on many mopar 2.7 V6's...replacing the oil pump and screen "fixed" a few of the cars ,others were run too long with too low oil pressure,and didn't fare so well................I haven't seen too many chevy's with sludge troubles other than a few that didn't get regular oil changes--as in NONE for many thousands of miles...but it can happen to any engine..