Oil presure AGAIN

Last winter I had my 4.7 apart like all winter to replace head gaskets. Cleaned and re surfaced heads, cleared a ton of sludge, clean as a whistle.

Put it back together, oil pressure would drop from time to time to zero.

Sold it that way, guy pulls the pan off and cleans sludge, cleans the screen, pulled the front back off and replaced the oil pump.

Oil has been changed 4 times in the last 200 miles LOL and is crystal clear.

I got the truck back and have been driving it daily no problems.

Yesterday I took it about 30 miles at 70MPH on the highway. When I slowed down for the exit... DING DING check gauges. Sure enough, oil pressure. Came right back as quickly as it left and has not done it again.

I'm thinking restricted passages in the block and it all pooled in the valve covers, braking took remaining oil in pan slung it to the front avoiding the pickup tube till it could drain back down.

First theory. Would like to hear others based on experience with this thing known as a 4.7. Arrrgh.

I did not see that you changed it but did you put a new oil pressure sending unit in?

Yes second guy did. In doing so he also removed the splitter and fitting I had on there for a manual oil gauge which I plan on putting back on this week.

So yes it was replaced.

any luck? I now am experiencing the "check gauges" and oil pressure dancing at idle. Check gauges dings on usually when slowing down or turning then will disappear.

No I have not torn into mine again yet, still mad at it.

I'm like 70% convinced the guy lied about replacing the oil pump.

Replacing the oil pump and cleaning the screen/pickup tube should cure the pressure drop problem.

I myself have decided to just get another motor and rebuild it over the winter. Easier sounding than it is because only a few motors have the 16 tooth reluctor ring I need. So far I can't find one that doesn't have a hole in the side from someone ignoring the pressure drops.

My issue seemed to be solved by adding oil. Was low causing the gauge to act up exactly like everyone else posts and the check gauges light coming on randomly especially when turning or braking. Filled up on oil and was on the road for 5 hrs total yesterday with it never coming back once. I have to figure out why I all of a sudden have oil loss hopefully a curable leak and not burning it.

PdPuNOme said:

My issue seemed to be solved by adding oil. Was low causing the gauge to act up exactly like everyone else posts and the check gauges light coming on randomly especially when turning or braking. Filled up on oil and was on the road for 5 hrs total yesterday with it never coming back once. I have to figure out why I all of a sudden have oil loss hopefully a curable leak and not burning it.

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How much oil did you have to add?

Also i would suggest running a can of marvel mystery oil in the oil (or regular ATF transmission fluid) as the final quart. Run it for a few hundred miles then change the oil to full synthetic to help keep sludge down in that engine.

I run high milage full synthetic. I added a quart. Engine runs strong getting 17mpgs and today 15.5 towing so this is a out of nowhere issue for me. Oil was last changed less than 2500 miles ago. This engine has roughly 80k on it original engine lasted till 175k.