I think I maybe got lucky for a while... Even if not, I have three spare B18 heads if I did really screw this up...

So... last time I was stopping vacuum leaks and replacing gaskets, I managed to break my forward manifold stud. Having limited time and no decent screw extractors, I left as was for the week and got back to it this weekend when exhaust leakage was really becoming a problem.

The stud was snapped off at the surface and required that I drill a pilot hole to get an extractor in there.

Nothing went well... The distance from the head to the inner fender is such that I could not get my drill in there at a proper distance. And then the damn thing skated off center. Then the screw extractor made things much worse.

Since this has worked for me several times before, I decided to re-tap the hole for a 5/16" stud. That went sorta okay...


The main issue here is that when I was enlarging the drill hole the drill went in at something other than perpendicular and suddenly bored into an open area. Nothing came pouring out (like coolant or oil) so I'm pretty sure I did not pierce the super important parts of the head...

I used a probe to measure the depth of my new hole and compared it to one of my spare B18 heads. It seems that at maximum, the drill bit could have gone as far in as the far edge of the headbolt tunnel. From the direction, my best guess is that the drill went into the headbolt tunnel, but skipped more towards the #1 exhaust tunnel side of the headbolt tunnel.

I removed the thermostat to look for signs of piercing the coolant reservoirs and water-jacket, and was greeted by a lot fo coolant bubbling up. I reasoned that if there is that much coolant under the thermostat, then it woudl have come pouring out if my stud hole had pierced he jacket. So...

After I finished the shallow tap for the new stud, I buttoned everything back up and test drove it. Everything seems fine. No leaking fluids, no overheating, no weird engine noises.

I think I got off lucky, but I'm thinking that when time allows (or necessity requires), I should probably pull the head and at the least replace that headbolt. If I really screwed it up, I can always swap on the head from the car's original motor (which needs to be re-assembled) or I can just drop on the 67 B18 head from my Wagon's original motor.

At such a time I could remove this head for a more thorough inspection, and maybe a helicoil to restore the proper angle to the #1 stud.

Fun stuff. Please let me know if you have any theories on my catastrophe.
If there was a *far* easier way of getting that stud out, also please let me know. I do not ever want to repeat this experience!

Make sure that you chuck all the studs & replace them with grade 8 bolts. Provided you lube the bolt when you install it, they will spin out with ease if you break them.

RJ,

Not that you asked for advice on getting the stud out...but having a drill skate was the start of the problem. I've recently purchased a used set of dental drills that I use in my Dremel for starting pilot holes in this exact situation. I bought them as I had to drill and tap about 70 1/2 deep 4-40 holes into 6061-T6 aluminum for a project I was designing at work. About half way through I broke a tap in the hole...the part is worth several thousand dollars and the holes must be exactly placed. The dental drills drilled out the tap! I've since used them on broken studs to start holes after centre punching - works great.

Craig

Much the same thing happened to me, about a dozen years ago. I had put together a replacement B20 for my 75 245, using the original head (with hardened seats) and a good 6 bolt bottom end from a 72, with new rods and mains, cam bearings too if I remember correctly. New cam and lifters. The pistons looked very good, so I put them back in, with new rings. Valves lapped in, new seals etc. Got the motor all put together, put it in the car, and was reinstalling all the accessories. For some reason, I did everything on the left side first, then moved over to the right. Manifolds on, tightening things down. It was late in the afternoon, and I was expecting to drive the car home (from my friend's shop) that evening. All went well until SNAP!!! the last stud broke on the final round of tightening. It was the one at the bottom, all the way at the back, that also holds the water pipe. No easy-outs on hand, and I don't trust them anyway (you're REALLY screwed if you break one of those off in the hole) As this was at the rear, and a 240 has a strut front end, there was no way to get a drill in there, so there was nothing for it but to pull the head back off and drill it out on the bench. I think I ended up using the drill press, which went well---I was able to get the hole perfectly centered and it went in dead straight. The first round was with a 1/8" bit, and I gradually increased the size in steps until I was at the root diameter of the threads. This left a perfect spiral of what had been the stud, that was easily removed with a dental pick, leaving the threads in the head in perfect condition. Very satisfying. Less satisfying was putting it all back together, having to wait until the next day and spend another $40 for another head gasket set (they didn't have just a head gasket at the parts store) replace ALL the manifold studs (just to be sure...) adjust the valves yet again, and so on.

In your case, I can't think of any way out other than what you did, or what I did. I agree with your theory that if you had drilled into the water jacket, it would have been obvious, with the coolant still in the engine. If I remember correctly, the oil feed to the rocker shaft is in the second pedestal, so you weren't anywhere near pressurized oil. Possibly replacing the head bolt in question seems like a good idea, as you might have nicked it with the drill. I think I would chance doing this with the engine stone cold, just pull that one out and replace it, then retorque them all to a slightly higher figure than when you originally assembled the engine. (don't go way past the factory spec, just a couple more ft.-lbs. all around)

Ah good to know I'm not alone in this.

You know, I think I was tightening that particular bolt last, which is why I said "screw it" and left it as was for a week.

Things seems okay for an extended run today (aside from my other issues) so I may really be ok here.

lucky, I guess.

I'll pan to remove the whole head next time this happens. Good thing I have spare heads and a spare head gasket on hand. Autoparts stores around here tell me things like "discontinued" when I ask about gaskets.

"Autoparts stores around here tell me things like "discontinued" when I ask about gaskets."

I would only caution... don't overlook the obvious. I picked up a B20e head gasket this week for the race car at Autozone. Just $26, and a brand name piece to boot (Felpro). Obviously had to be ordered, but it took all of about 36 hours for it to come in. Haven't peeked, but if they have B20 gaskets, they might have B18 gaskets as well.

Gary L
--
1971 142E ITB racer, 1973 1800ES, 2002 S60 T5

I was at carquest, but I generally only buy fluids and tools at autozone they do not have 120 U-joints, and they cannot find a 140-style airbox filter, even if the computer says they should have it.

Many years back, I got many of my 140 parts there (calipers etc), but my mechanic at the time recommended buying my parts from NAPA. My local autozone mainly sells to the Bosnians and the local Ricers and while they all think my vintage volvo is cool, they can rarely help me out with specific parts. There is no Napa near here, so I usually just buy online - the prices are always better anyway.

I think you'll be OK...
I might have coated the new stud with some kind of sealant, but it doesn't sound like that's necessary.

Did you put a new gasket on there though? I expect after a week of exhaust leak, that old one is compromised.. maybe have to replace that soon.... maybe not.

--
-Matt I ♥ my ♂

I used some loctite red on the studs, it seems to hold up okay despite all the heat.

My gasket was not really toasted, so I reused it after a careful inspection. Weirdly, the main leak was down at the downpipe/manifold connection... One nut was missing entirely and the other two had worked loose. Kinda odd as they are the bi-metal types.

I've been checking the head and that bolt in particular every time I run the car and so far no leaks or weird behavior. So I'd tentative agree, that if you look up luck in the dictionary, you might see my picture...

Then again, my clutch master failed at precisely the same time (last night) and I spent the last couple hours pulling and rebuilding it. No obvious connection to the manifold, just a coincidence I guess.