Oil pressure low

[Angelo217]

I think that's what happened to my Express van. Had the 4.8 with the 862 heads--which are known to be prone to cracks. When i sold my van the oil pressure was basically at 0.View attachment 443066View attachment 443067
Your oil pan might have similar sludge too.

My oil pan was very clean. Literally had to do virtually 0 cleaning when I dropped it. Was the original gasket btw. Hasn’t been dropped/ cleaned for 230k miles.

 

[Angelo217]

My 2004 with high mileage was doing the same thing on the original 5.3 engine. What I found out over time, is it had what started out as a very small coolant leak from a Castech head and when the oil was changed, it would return to better oil pressure. Over time, and as miles added up the oil was being compromised and polluted with just a little bit of water/coolant. As time went on, and the leak got worse, the time period of good/standard oil pressure became shorter and shorter since the oil was being compromised quicker.

When the engine is cold, pop your oil cap off and look on the underside/inside the cap. Do you have what looks like droplets? Sometimes you can even see evidence of coolant pollution in the fill tube that the cap screws into. That is what I observed and found out on my Tahoe, YMMV.

I have an old thread here from years ago asking the same thing as the original poster in this thread.

I’ll check this for sure. I’m fixing to throw in my new oil pressure sender sensor. Along with intake manifold gasket, because for some odd reason my sensor is a different size from the factory sensor. 1” 1-16 or whatever it is

 

[Angelo217]

It is also possible that the pressure spring in the pump is getting weak.

Would this cause a drop in pressure after it warms up?

 

[Angelo217]

If you overfill the oil after the motor is warmed up at idle and the pressure goes up by 5/10lb you can verify if the O ring on the oil pump is bleeding air into the system or … replace the O ring, it’s bad.

Be sure to drain extra oil out b4 u drive it. You could also swap out the oil pump and replace with a HD version.

I’ve already replaced my o ring. Red to red. Mahle, red was in there replaced with a red o ring. My o ring really wasn’t in the worst shape, was just flattened. No cracks or major deformities. And oil pressure is maybe slightly better on average after changing that out 5k miles ago.

 

[Fless]

I’ll check this for sure. I’m fixing to throw in my new oil pressure sender sensor. Along with intake manifold gasket, because for some odd reason my sensor is a different size from the factory sensor. 1” 1-16 or whatever it is

There's a special socket for the sender. Although a standard socket may work, it could damage the electrical connection on the sender when it's tightened down, and may experience interference with the intake manifold.

 

[Angelo217]

My 2004 with high mileage was doing the same thing on the original 5.3 engine. What I found out over time, is it had what started out as a very small coolant leak from a Castech head and when the oil was changed, it would return to better oil pressure. Over time, and as miles added up the oil was being compromised and polluted with just a little bit of water/coolant. As time went on, and the leak got worse, the time period of good/standard oil pressure became shorter and shorter since the oil was being compromised quicker.

When the engine is cold, pop your oil cap off and look on the underside/inside the cap. Do you have what looks like droplets? Sometimes you can even see evidence of coolant pollution in the fill tube that the cap screws into. That is what I observed and found out on my Tahoe, YMMV.

I have an old thread here from years ago asking the same thing as the original poster in this thread.

I will take a look when it’s cold again. Haven’t lost any bit of coolant over 6-7k miles or so but I will look thanks man

 

[Angelo217]

There's a special socket for the sender. Although a standard socket may work, it could damage the electrical connection on the sender when it's tightened down.

Yea I have the special socket for it at my shop. It works on the new OEM delco one I just bought, but won’t grab on the existing sender that’s in my motor right now for some reason… thinking the previous owner already tried this LOL. We’ll see what I got myself into. Worse comes to worse I’ll rebuild this one or get myself another 5.3. But I’ll try and bring this one back around.

 

[Angelo217]

Appreciate yall for the help. Also another mention about my rear main it’s absolutely just puking at this point. And im honestly really pointing my finger towards that. When I park oil is just all over my bell housing, watching the drops of oil fall down every 2 seconds after parking.

 

[Mudsport96]

Would this cause a drop in pressure after it warms up?

It COULD, as the oil is thinner and would flow passed the relief valve faster. In case I missed it, how does the pressure look when you drop the hammer to pass someone on the highway?