what is this hole for and how to clean it
i may be way off but i think it is just a spot where the casting did not form perfect. i am sure there is a technical name for it but i don't know what it is. i have seen spots like that in other spots on engine blocks. most of the time i see them is a corner like that. i figure that the heat or air may affect those kind of areas when they are formed. i am no expert on the subject but i am sure a true expert will give a better explanation.
Last edited by jensenracing77; Dec 21, 2009 at 05:20 PM.
Is there any of these on the passenger side?
That is the oil drain back from the valve train. More than likely the gunk you see is hardened or baked oil. This needs to be removed or oil will be trapped in the valve train are. Just try and not let the gunk fall into the engine when you remove it.
Doctor D. comes through!
I believe it to be a rare,but potentially deadly form of Squamous Cell Rust Cancer, though this can only be confirmed with a biopsy. If proven to be such, it will require a wide excision,and careful followup to prevent recurrance. And you "mechanical" guys thought I had nothing to offer by way of helpful insights!
Merry Christmas to all, and to all a good night.Dr.D.
https://classicoldsmobile.com/forums...ease-help.html
Check out this thread with some pictures of the same hole that I modified to insure quick drain back........That one you have has some issues.
Check out this thread with some pictures of the same hole that I modified to insure quick drain back........That one you have has some issues.
OK... maybe I need new glasses but this looks like it's right under the head. The only thing behind it would be the water jacket. Aren't the drain back holes down near the bottom of the valley near the lifter bores? rtpassini can you post another photo but pull back so we can see the whole lifter valley?
John
John
I am thinking the same thing 2blu. I looked closely a couple of times. BigJerr's pictures show the drainback holes he modified which are definitely in a different place. In the first picture rt showed that hole is just below the block/head mating surface which is much higher in the block. I think that is part of the distributor in the picture that is kind of out of focus. It looks like corrosion to me. I think the Dr. was right.
THey look like the same thing to me. Only difference is BIGJERRs picture is at the front of the engine instead of the back. These drains are at every corner if memory serves. I don't know if oil drain is correct though do to the location. Possibly a PCV hole for crankcase pressure from the lifter vally.


OK... maybe I need new glasses but this looks like it's right under the head. The only thing behind it would be the water jacket. Aren't the drain back holes down near the bottom of the valley near the lifter bores? rtpassini can you post another photo but pull back so we can see the whole lifter valley?
John
John

Boy, do I feel like an idiot!

Clearly I screwed up. The hole I pointed out (that was so nicely "circled" by jensenracing77) would be under the accessory boss at the bottom of this picture. As we can now see in this photo, the oil drainback hole in the head is angled and does, in fact, empty into the valley.
DOH! Sorry for the misinformation.
It's been a while since I had one apart.As noted correctly by others above, that casting flash needs to be ground out eventually, but not with the engine together. In the meantime, you can clean the caked oil out of the drainback hole with a stiff wire or drill bit. Be sure to collect all the debris. I would suggest using a shop vac while you chip out the blockage.
I have faith Joe.
The Wiki has stuff about that and how to do the holes for better flowback. Those external oil return lines would eliminate any worries.
It's in buildups under oiling if anybody wants to look.
http://www.oldsmobilewiki.com/index.php/Main_Page
I had a 312 Y block Furd and those things got no oil to the rocker arms.
You had to run copper lines from the oil filter adapter to holes you drilled in the valve covers to get some oil up there, very common fix and they sold kits to do it at every parts store back in the day.
I ripped the boat anchor out and put in a 390 a la an old Hot Rod magazine I found at the Goodwill.

The Wiki has stuff about that and how to do the holes for better flowback. Those external oil return lines would eliminate any worries.

It's in buildups under oiling if anybody wants to look.
http://www.oldsmobilewiki.com/index.php/Main_Page
I had a 312 Y block Furd and those things got no oil to the rocker arms.
You had to run copper lines from the oil filter adapter to holes you drilled in the valve covers to get some oil up there, very common fix and they sold kits to do it at every parts store back in the day.
I ripped the boat anchor out and put in a 390 a la an old Hot Rod magazine I found at the Goodwill.
tell that to your wife!!!



ya, you are 2. Don't get hand dog down on us now. You have a 455 sitting in your basement? How many of ya did it take to haul it down there? If I pulled that with my wife, I'd be living in the storage shed.
YOU DA MAN!!!




YOU DA MAN!!!
Something to think about, I saw this at the Chev dealer in the parts section just a week ago. They now sell a custom magnet for your oil filter so it will keep any metal shavings or filings that happen with normal engine wear from being recirculated through the block. It was pricey. Do any of you do this? Put a large magnet along the side of oil filter the same way? It doesnt fall off and the results I saw at the parts counter were quite impressive...
Nice to see that there are humble guys in the forum who are willing to admit they can be wrong sometimes, makes me proud to know you all. Sniff, sniff, now I can go out and grind down my oil passages with confidence now that I know for sure were they are located. 


Boy, do I feel like an idiot!

Clearly I screwed up. The hole I pointed out (that was so nicely "circled" by jensenracing77) would be under the accessory boss at the bottom of this picture. As we can now see in this photo, the oil drainback hole in the head is angled and does, in fact, empty into the valley.
DOH! Sorry for the misinformation.
It's been a while since I had one apart.


