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+T Oil Return Tragedy

iHateVolvoPeople

Active member
Joined
Feb 1, 2014
Location
Midwest
This started off as a very simple engine reseal plus a +T conversion. I initially was going to return to the pan like I always do, but figured since the engine was already out, I'd get a cleaner look returning to the oil return boss.

Fast forward to yesterday, I center punched the boss, then I started with a small bit, greased it up and drilled slowly. All was going well and I was roughly 90% of the way through and then SNAP. I broke the bit. So I drilled a slightly larger hole next to the broken bit, and was able to make it through the block entirely. Then the next bit size up, broke another.

So now were stuck with a half drilled hole and 2 broken bits. Had 2 machine shops tell me there was 'nothing they could do' and recommended a new block. If that's the case I'll just abandon the block return and go to the pan.

I'm unable to even see the broken bits anymore, but I know they are there because I've dulled 6+ bits trying to get through.

Anyone ever dealt with such a **** show?

First broken bit
141tqcdl.jpg


Then I drilled a hole next to the bit and broke the 2nd bit.
CWGaZ1nl.jpg


Here's where we currently stand
dGvrQe4l.jpg


So at this point it looks like my best bet is to abandon this block return and do one in the pan. In the future, I'll drill even slower and with better drill bits. I was using new milwaukee titanium bits.
 
Pilot hole is too small, lower the motor speed, don't push so hard, use different drills, use Tap Magic cutting fluid, keep it straight.

Don't try to drill through broken drill bits with other drill bits.
 
Pilot hole is too small, lower the motor speed, don't push so hard, use different drills, use Tap Magic cutting fluid, keep it straight.

Don't try to drill through broken drill bits with other drill bits.

I've never done this before and clearly should've done more research. Oh well, live and learn. I'll be returning it to the pan I guess, otherwise it's just going to become even more of a money pit than it already has been.
 
I've never done this before and clearly should've done more research. Oh well, live and learn. I'll be returning it to the pan I guess, otherwise it's just going to become even more of a money pit than it already has been.

cast iron can be really "grabby", so you'll have more margin for error with a bigger bit. Slower helps and imo the cutting fluid makes a big difference.
 
A stepped bit will not work for this. They are more for 1/8 or thinner material. You can drill through those bits if you want to spend the money for a good carbide drill bit. However you have to be careful with them because they are brittle and will break easily. Some sort of lubricant is a good idea when drilling any kind of metal. Cast iron is a bit more forgiving then most in that respect tho.
 
you need to hold the drill straight.
arrange a surface nearby you can rest and guide the drill on, or sneak the engine stand under the drill press.
Size the drill appropriately, a pilot hole in cast iron that deep should be 1/4 inch or even bigger. hand drilling a hole 10x deeper than diam of bit is recipe for disaster.


I remember you telling me you were a lot smarter than I thought. nope
 
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you need to hold the drill straight.
arrange a surface nearby you can rest and guide the drill on, or sneak the engine stand under the drill press.
Size the drill appropriately, a pilot hole in cast iron that deep should be 1/4 inch or even bigger. hand drilling a hole 10x deeper than diam of bit is recipe for disaster.


I remember you telling me you were a lot smarter than I thought. nope
:urgod:
Honestly same.
But what now?

Jb weld the hole and just drill through pan?
Yessir. More fail pics coming soon
 
We all do basic mistakes. Just do the needful and move on with that bit of wisdom stashed away.

Did that pulley end up working out?
 
We all do basic mistakes. Just do the needful and move on with that bit of wisdom stashed away.

Did that pulley end up working out?

Haven’t used it but it looks to be in good shape:nod:

There are certain jobs I willingly admit I should leave to pros. Clearly a simple hole in cast iron is one of them. Doesn’t matter either way, the oilpan return turned out decent enough. I put a horrible bead of JB weld around the perimeter anyway for cheap insurance.

Trust me, this hole is far from the ugliest part of this car.
 
I just drilled my a few weeks ago. I will say this was the hardest cast iron I’ve ever drilled. I elected not to tap mine I Bj welded a fitting in it. Anyway I went and spent money on the best bits I could find locally. If the motor is out I’d do the pan. If it’s not out I would go buy some good bits. I spent a small chunk on bit. I looked at it like this. What’s it worth to not to pull the motor out. So I figured 50 bucks saved me a lot of work.
 
QLxX8Vfl.jpg


Then a halfass first coat of JB weld around it (even though it would've been fine without anything)
ElfcGufl.jpg


Gonna add another coat once the first one dries.

Same story with this:rofl:
WPtvI1Ml.jpg
 
the quarter lol

Tbh idk if it’ll hold, but my broke off drillbit sealed the original hole anyway so I could’ve left it as is.

This really sucks because it’s so ugly and everything else was going so well with the engine.

13mm rods, all Volvo OE seals, machined head, valve job, etc etc. just gonna have an ugly block I guess.

The good news is that my friend is the original owner and wants it back, and he’ll likely blow it up in under a week so we’ll never have to see it again.
 
I have done similar things drilling out broken accessory bolts out of the block (actually snapped hardened extractor). I ended up grinding out the broken using a decent carbide deburring bit on a rotary tool and then going back to drill. fwiw
 
I have done similar things drilling out broken accessory bolts out of the block (actually snapped hardened extractor). I ended up grinding out the broken using a decent carbide deburring bit on a rotary tool and then going back to drill. fwiw

Wow that?s actually a really good idea, never even thought of that. Those burrs are aggressive and likely would?ve made it through.
 
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