Low oil pressure....sometimes

[tjoyce81]

The most likely cause of a low oil pressure issue in a 5.3 is a blocked oil pressure unit screen or an oil pump o-ring failure. HOWEVER - there is an often overlooked and very common issue that puts many of these engines in the junkyard FOR NO REASON. It is a weak or failing oil pressure relief valve inside of the oil pan. If ALL of the above does not fix the oil pressure issue - it IS the relief valve inside of the oil pan. The spring wears out in these valves, which causes oil to simply dump into the pan - and not feed the upper part of the lifter feed circuit. The oil pressure sending unit is located in this circuit - which is the reason you get a low oil pressure indication - when in fact oil pressure is good. The fix is to either replace this valve, or to simply install a plug so the oil does not dump into the pan.... When you block this off - oil pressure will be better than before....

 

[Reebok59]

I finally got around to dropping my oil pan to change out the o-ring in the oil pump pick up tube. As reported earlier in this thread, I was experiencing low oil pressure (~10 psi idling in gear and ~20 psi in nutural) when the engine was cold and once it got up to operating temperature, no problems (35+ psi). I had to put it in nutural at red lights to keep the oil pressure up around 20 psi until it hit operating temperature. The issue was very repeatable which convinced me it was an o-ring issue and not a pressure sensor or plugged filter screen issue. It was suspected that when the oil was thicker, the o-ring would leak and suck air. Once the oil heated up and got thinner, the o-ring would not leak as bad.

Well, I am very happy to report that it was definitely the o-ring! I found the o-ring to be flattened on the O.D. and it had many small cracks like dry rot. Upon inspection of what looked like a larger crack or gouge, it cracked all the way through. Now my oil pressure is ~40 psi cold and very small drop idling in gear. No more putting in nutural at red lights! :=)

If wondering, it has 180K on it. And I could have kicked the dealers ass for not replacing the o-ring at 115K when the oil pan gasket was replaced!

 

[mackmcmillan]

I finally got around to dropping my oil pan to change out the o-ring in the oil pump pick up tube. As reported earlier in this thread, I was experiencing low oil pressure (~10 psi idling in gear and ~20 psi in nutural) when the engine was cold and once it got up to operating temperature, no problems (35+ psi). I had to put it in nutural at red lights to keep the oil pressure up around 20 psi until it hit operating temperature. The issue was very repeatable which convinced me it was an o-ring issue and not a pressure sensor or plugged filter screen issue. It was suspected that when the oil was thicker, the o-ring would leak and suck air. Once the oil heated up and got thinner, the o-ring would not leak as bad.

Well, I am very happy to report that it was definitely the o-ring! I found the o-ring to be flattened on the O.D. and it had many small cracks like dry rot. Upon inspection of what looked like a larger crack or gouge, it cracked all the way through. Now my oil pressure is ~40 psi cold and very small drop idling in gear. No more putting in nutural at red lights! :=)

If wondering, it has 180K on it. And I could have kicked the dealers ass for not replacing the o-ring at 115K when the oil pan gasket was replaced!View attachment 242735

Awesome work! Did you happen to do the Corvette servo upgrade then or prior?

 

[Rocket Man]

I finally got around to dropping my oil pan to change out the o-ring in the oil pump pick up tube. As reported earlier in this thread, I was experiencing low oil pressure (~10 psi idling in gear and ~20 psi in nutural) when the engine was cold and once it got up to operating temperature, no problems (35+ psi). I had to put it in nutural at red lights to keep the oil pressure up around 20 psi until it hit operating temperature. The issue was very repeatable which convinced me it was an o-ring issue and not a pressure sensor or plugged filter screen issue. It was suspected that when the oil was thicker, the o-ring would leak and suck air. Once the oil heated up and got thinner, the o-ring would not leak as bad.

Well, I am very happy to report that it was definitely the o-ring! I found the o-ring to be flattened on the O.D. and it had many small cracks like dry rot. Upon inspection of what looked like a larger crack or gouge, it cracked all the way through. Now my oil pressure is ~40 psi cold and very small drop idling in gear. No more putting in nutural at red lights! :=)

If wondering, it has 180K on it. And I could have kicked the dealers ass for not replacing the o-ring at 115K when the oil pan gasket was replaced!View attachment 242735

Nice!

 

[Reebok59]

Awesome work! Did you happen to do the Corvette servo upgrade then or prior?

No. No transmission work yet. Now that it's at 180K, that service comes next. I wanted to do the oil pan gasket and o-ring myself first. Now on to the transmission shop for servicing. It been serviced every 30K. May do the servo upgrade, need to research more first.