Is this hole behind my oil pump gear normal?
 

So, I’m looking at my block trying to understand and plan for the 95% mod and I noticed an interesting hole behind the oil pump drive gear. From what I can see, it just dumps straight back into the crankcase. I did some googling to try to see if other blocks had this hole and the one picture I saw showed one in that spot, but it was much different, like a drilled hole instead of the hole in my block which looks like it’s a chunk missing. If it matters, this is a 49-53 8CM. Thanks in advance. https://uploads.tapatalk-cdn.com/202...32da5b00f1.jpg

Re: Is this hole behind my oil pump gear normal?
 

Although a little different shape, the two I looked at are the same.
Gives a place for residual oil in the valve chamber to drain back to the pan while providing a little lubrication to the gears.

Re: Is this hole behind my oil pump gear normal?
 

Thank you. Would be interested to know why that's there if anybody can tell me. I haven't gotten the books I ordered yet, maybe they will say.

Re: Is this hole behind my oil pump gear normal?
 

Read post #2 again.

Re: Is this hole behind my oil pump gear normal?
 

Ah, I think he edited to add that since I replied, or I am blind. Thanks.

Re: Is this hole behind my oil pump gear normal?
 

50MercMetalHead


This will be an "EDIT Test". DD


"THIS is edited"! Note "EDIT and time mark below in italics!

He DID NOT Edit!


.

Re: Is this hole behind my oil pump gear normal?
 

I just went downstairs and checked my block .
It’s a 49 Merc,,,,,and has the exact same shaped hole there as yours .
Yours is perfectly normal,,,,don’t worry .
I took some pics but it is bolted to an engine stand,,,so the pics are not perfect .
And it’s a bear to post pics here .

Tommy

Re: Is this hole behind my oil pump gear normal?
 

Thanks for checking. Appreciate it.

As for my confusion on the possible edit, I noticed it didn’t say it was edited, but I quoted that reply, and looking at my quote it didn’t have the second part, I also don’t remember seeing it before I replied the first time so that’s why I thought it was edited in. Maybe a glitch on my end cause I’ve got some wacky middle-of-nowhere internet. Doesn’t matter in the slightest though, I got the info I was after and I am thankful.

Re: Is this hole behind my oil pump gear normal?
 

That "hole" prevents pressure potential in the gear case which could lead to serious leakage at the gasket face. If you pressure feed your oiling system and observe the outflow into the lifter galley you will see what that hole is all about.

The fit of the oil pump in the block is not perfect. Some worse than others. Also the pressurized oil escapes through the upper pump bushing of which much goes into the gear case.