just got this oil pan, has a small chunk broken out of this hole that appears that it should be blocked off. i don't know what the purpose is for these two holes and why one (the one that has a chunk missing) should be blocked.

what to do? is this junk that i need a refund for?

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Haven't looked closely at the pan in that area, the other side of that holds the filter yes? Can you get a picture of the other side, may help?

 

yes, filter on other side. this hole was obviously cast with a bottom in it- so assuming it needs to be blocked off

 

I wouldn't block it off if you want oil to get to your filter.

 

well i am sure GM didn't design this to look like it has been broken. anybody got any help with this??

 

Yes they did. That's exactly how mine looks and the 2 other ones I have on the shelf. If you block that off you will get no oil to your filter.

 

see?

 

it was cast with a bottom in it, but it was drilled out during final machining. its typical machining and casting flaws, the entire engine is littered with them. if it bothers you that much, get in there with a dremel or something and clean it up. but do NOT block it off.

 

Not a problem. The oil flows through those two holes and also through that hump between the two bolts in the oil-cooler block off plate as it goes to and from the oil filter.

 

bww, i owe ya. it sure looks like somebody knocked out part of that aluminum!! why not just drill out the whole thing in the casting/machining process???? crazy. but i really appreciate the help!! glad to know it is normal and not busted.

 

It's all about time...the hole and casting are good enough to function correctly...seconds of time in the CNC machine, when making hundreds of thousands of oil pans, is a HUGE deal...plus, drilling further and further into a side exiting cavity like that wears the cutting tools faster and faster...which means more cutter replacements, and potentially more down time (if the operator of the CNC machine isn't able to change the tool while the machine is running), and that all translates back to lost $$$$$$$.

A lot of the time, an engine builder looking for every last bit of HP, will take a die grinder and other tools similar to what they'd use on cylinder head ports, and port everything where anything flows, oil/coolant/air/fuel...anything that the engine needs to pump, is a parasitic loss...anything that can help it pump it easier, is essentially more efficiency/horsepower.

GM most likely knows that the gain would be minuscule, so the part is good enough for a production vehicle...when you're looking for every last individual horsepower on an all out NA build though...you don't care how minuscule a gain is...a gain is still a gain.