Oil pickup screen bypass hole?

[Tony Tee]

Took apart a oem big block pickup tube and found this hole in the middle. I never knew it was there. Are all the oem pickups made with this hole? I guess its for when the screen is totally clogged and then it pushes the screen and lets in all the garbage ? Or is this hole always open?

 

[69Bee]

The hole seals against the metal cover, and if/when the screen becomes plugged enough, the suction will pull the screen down thus allowing unfiltered oil to bypass the screen and prevent a non-oil condition.

 

[69 Sleeper Bee]

I agree with 69Bee above and got curious and just checked a new pickup I have for a new build and it's hard to tell from the picture but I got my light in there and it is solid screen with no bypass hole that I can see.

 

[69Bee]

I believe that only OEM ones have it. With today's oils, you don't see the varnish and sludge buildup like yester-years oils so that is likely why Melling omits them.

 

[Tony Tee]

I agree with 69Bee above and got curious and just checked a new pickup I have for a new build and it's hard to tell from the picture but I got my light in there and it is solid screen with no bypass hole that I can see.
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Thats good to know. I prefer not having that bypass hole. Thanks!

 

[pnora]

Took apart a oem big block pickup tube and found this hole in the middle. I never knew it was there. Are all the oem pickups made with this hole? I guess its for when the screen is totally clogged and then it pushes the screen and lets in all the garbage ? Or is this hole always open?View attachment 1958555View attachment 1958556

That bypass trap door was the demise of many oil pumps and broken distributor drive shafts. It would let chunks of valve seals through and jamb the oil pump and then snap the shaft. Car kept running with no oil pressure. Killed many motors.

 

[Tony Tee]

It almost killed my 440 back in the 80's when the camshaft plastic coated timing chain sprocket fell apart and the plastic got embedded in the main and rod bearings. Now i know how it got passed the dang pickup screen.