Drilled through cylinder head water jacket.

[i3adme]

So I did it, my dumbass drilled through a water jacket on my passenger side cylinder head. Was trying to drill out a broken valve cover screw, and created a water fountain in my garage. Tried plugging it up, but now it’s leaking into the oil pan.

It really didn’t feel like I went that far down, but in any case I think the head is toast. I’ve got an ‘86 302 with a mild flat tappet cam. My concern is that I’ve somehow screwed up my block. Guess I won’t know till I take the head off.

Anybody ever do this before? I feel real stupid right now.

 

[Rustytruck]

is the hole in the right place for the valve cover screw? if so just tap it and screw in a stud with a gob of epoxy on it.

 

[i3adme]

is the hole in the right place for the valve cover screw? if so just tap it and screw in a stud with a gob of epoxy on it.

It was right through the upper left valve cover screw hole. I tapped it, made a stud and covered it in jb weld. Waited 24 hours before refilling it with coolant. Didn’t appear to leak, but then I started noticing my oil thinning out. Just drained the oil and it’s about 5-10% coolant mixed in. Took off the valve cover and my stud fix is dry as bone, but milky color oil all over the valve train. Oil pan bolt hole is still dripping out what looks like coolant.

 

[Rustytruck]

when it first leaked out the hole the coolant ran down the drain back oil holes in the head. from the top down.

 

[Rustytruck]

go to the auto parts and borrow a coolant pump test kit orileys and auto zone usually rents them out for free with a returnable deposit. pump up 10 pounds and see if it holds pressure.

 

[i3adme]

go to the auto parts and borrow a coolant pump test kit orileys and auto zone usually rents them out for free with a returnable deposit. pump up 10 pounds and see if it holds pressure.

Good idea, I’ll check the parts store up the street tomorrow.

 

[Broncobowsher]

Didn't hurt the block. You were not anywhere near the block.
Sealing the threads should be all you need. Rocker arm studs go into the water jacket (for better stud cooling) and it isn't an issue.
The water in the oil is probably an artifact from the water leaking out the hole and running into the engine. It can take a few oil changes to flush all that water/oil mix out of the engine. I've had friends dunk ATVs and they would change the oil, run it 5 minutes, change it again. Repeat a half dozen times, mostly because the little engines don't drain that well.

 

[i3adme]

Didn't hurt the block. You were not anywhere near the block.
Sealing the threads should be all you need. Rocker arm studs go into the water jacket (for better stud cooling) and it isn't an issue.
The water in the oil is probably an artifact from the water leaking out the hole and running into the engine. It can take a few oil changes to flush all that water/oil mix out of the engine. I've had friends dunk ATVs and they would change the oil, run it 5 minutes, change it again. Repeat a half dozen times, mostly because the little engines don't drain that well.

Man I hope so. Literally just got this thing rolling and here I go breaking it. It’s almost like I subconsciously don’t want it to be fixed. lol

I left the oil pan plug out, to let it drip over night and it’s still going. Got the radiator pressure test kit from Oriley’s, and it exposed a leak coming from the lower radiator hose. So I’m in middle of fixing that first, before I get back to the head problem. Draining coolant at the moment and will report back on my progress.

 

[i3adme]

Wholly crap this radiator pressure tool shows all your leaks! I’m a newb and totally had no clue this thing existed. So I’ve repaired the leak in my lower radiator hose, pressure tested, and get an even slower pinhole leaks coming from my over flow tank. Maybe drops a psi every 5-10 minutes or so. I can shake the truck and get coolant drips out the oil pan plug hole, but maybe Broncobowsher’s right and I just need to flush it out with a bunch of oil changes. I guess cheaper the oil the better for this process?

 

[i3adme]

Well the truck is all buttoned up. Siphoned as much of the contaminated oil as I could. Replaced the oil filter and all the fluids are back in. Test drive went okay, and the oil on the dipstick looks fine. I’ll keep an eye on it.

Thanks Rustytruck and Broncobowsher for all the help! You guys saved me from a knee jerk panic buy of new cylinder heads.

 

[blubuckaroo]

I drilled out a broken A/C compressor bolt and got into the water jacket. I pulled the head off and had a machine shop thread in a nickel plug and weld it in. fixed for good.

 

[Rustytruck]

At least the pressure test says your system is good and saved you from a hose leak pissing you off. been on this planet 62 years if I threw money at every perceived problem I would be permanently broke. it took me 40 years to calm down to problems. and I learned to never start a project on sunday when everything closes early. and stop throwing money at problems that are not verified. always check classic Broncos first before throwing money at your Bronco. its good to solve your problems but better if you can get family to point you in the right direction when overwhelmed. Have a good day brother..