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V6 150hp Test run after rebuild

I never made it to the lake! I went to replace the temperature sending unit and one of the bolts broke off in the block! Four of the twelve bolts ended up breaking off. I worked for several days trying to get the broken studs out, but I have been unsuccessful. I had to walk away and clear my mind of the frustration. I have managed to drill through all four bolts, not quite centered, but through them nonetheless. They still won't budge. My thought is to try and drill/grind/ out the bolts without damaging the threads. I just haven't acted upon that thought. I am just so disappointed in myself at the moment. I went from having a good running motor, to having a hunk of metal bolted on the transom. .... ... . .. . . .
 
Did you have those bolts out ( head bolts ) when the engine was apart ???----------Time to visit a machine shop to salvage the beautiful machine.---They can get the bolts out without damaging the block.
 
No, I never had the head bolts out. I figured that there was nothing broke in there, so why mess with it. Well, once I got it running it was obvious that the temp sender was not working, thus the adventure began. In order to take it to a machine shop, I'll have to remove the powerhead from the lower unit again, Just not looking forward to that. I assume that I won't be able to reuse all the new gaskets I just installed. Oh the wife is going to be tickled with me.

The funny thing is that the 30 year old factory head bolts are not hardened. There is about a half inch of the bolt exposed to the cooling water and every bolt has a narrow waist just above the threads. I bought grade 8 bolts to put back in once I get the old ones removed.
 
V6 150hp Test run after rebuild - Broken head bolts - Suggestions.....

Hello again,

I just got back to my boat project. The last thing I remember doing was trying to drill out those pesky bolts. Well, as you can see I was able to drill them out, but the bit went crooked on me. I did not hit the threads yet, but I am close. I have called my local machinist and he said he would take a look at it.

I tried the round and square EZ-outs, but they didn't help at all.

Does it look repairable? Have I totally messed this block up? It is a 1978 model, but everything else was going great. ..........

I'm afraid the other head should be removed as well (Just to be on the safe side) and that will leave more broken bolts.......

I'm just not sure what to do. I'm pretty sure I screwed up and I am ready for all of the "you idiot, what did you do that for" replies.....

Is there enough metal left to re-thread these holes ??

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I am curious how the motor was " rebuilt " without removing the cylinder heads ??---------At any rate make yourself some sort of " dummy cylinder head " out of steel ( 1-1/2" thick ) so that you can use it as a drill guide.
 
Greetings racerone,

I appologize if I misused the word "rebuilt". I joined the lower unit off a 80's engine to the upper unit of the 78 engine. It was a lot of work for me, so I considered it a rebuild. I can understand where I may have incorrectly used the term. This is my fisrt outboard as well as my first outboard repair :) and I do appreciate your response.

So once I make the dummy head with the required guide holes, do I drill out the existing threads and tap new ones?
 
OK. I found a piece of 1.25 inch steel plate. I'm going to layout the holes and have the machinist drill it on his drill press. I have been looking at Heli-coils to create new threads. Will these new threads allow me to torque the new bolts down or should I just drill the holes to the next available size? Then just tap the holes and insert new bolts into the aluminum block.

I just don't want to drill the holes too big.
 
Awesome News ! I met with the machinist this morning. He said "I've seen worse". He is going to build my jig using hardened drill bushings pressed into a block of 1 1/4 inch thick steel plate. One hole will have a 25/64 bushing and one hole will have a 3/8 bushing. The other two holes will just have a 3/8 through hole to allow me to line up the jig. I can then use a 3/8 four flute carbide end mill to drill out the remaining bolt. Once the bolt is out, I can rotate the jig around to the 25/64 bushing and drill the hole out for the heli coil insert. I sure hope this works.
 
My machinist was involved in an accident and is currently out of work. So, being such the resourceful guy, I built the jig myself! I just took my time and borrowed the neighbors drill press. It took me a couple hours but it turned out great and all four holes line up !!!! I bought the hardened drill bushings from Reid Supply as well as the carbide end mill. those dang bolts don't have a chance !


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Next time you or other people snap off a bolt, follow the Fastjeff Procedure and you won't create such havoc!

Jeff

Drilling out a broken bolt/ stud.

It happens to all of us, is frustrating and, if improperly done, can cause all kinds of damage (some times irreparable). The usual method is to ‘attempt’ to locate the center of the bolt/ stud, center punch it, and drill away. Unless you’re really lucky the hole ends up off center. The result of THAT, when you enlarge the drilled hole (for an Easy Out, or to drill it out) is a disaster: The hole migrates to one side and into the aluminum. Ouch, and a tough fix since the harder steel won’t allow you to drill the softer aluminum. (Can you say, “Oh crap!” )

Those guys with a milling machine just end mill that sucker outta there, but I don’t have one of them. So I use a method some old machinist taught me eons ago: I slant drill.

Here’s how it’s done: Start with the smallest drill you have (like a 1/16 “ drill to remove a ¼ “ bolt/ stud). Start your hole close as you can to the center of the bolt/ stud then, when you see it’s off center a bit (which it often is) angle the drill. Angle it up to 45 degrees and slant drill the hole towards the actual centerline. The next step is to ‘auger’ the hole out, producing a conically shaped hole that is centered. (You might have to angle drill more than once.) You now have a small hole dead center in the broken off bolt/ stud that you can step drill, a bit at a time, until it collapses with a sharp punch or, in the worst case, be re-tapped.
 
Thanks for the advice! That is exactly what happened to me. But on the bright side, it was definitely a learning experience and I now have a great tool to repair all of the bolts on the other head when I attempt to remove it next. If I were in this position again (without a jig) I think I would try a left handed drill bit first!
 
Awesome! I was able to get all 4 broken bolts drilled out without damaging the block. Next, I get to tackle the Heli Coil inserts.
 
I agree! I have always received great advice here! I am so happy (actually my wife is so happy) that I did not destroy a good engine!
 
I'm so excited! All four holes have been repaired! I also ran a tap down the old threads to clean them up as well! Funny thing, I was so concerned with repairing the holes, I forgot to order the new gasket! I suppose I'll work on something else until it gets here .

Thanks for all of the good advice!

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Re: V6 150hp Test run after rebuild - Broken head bolts - Suggestions.....

Donewright said:
Hello again,

I just got back to my boat project. The last thing I remember doing was trying to drill out those pesky bolts. Well, as you can see I was able to drill them out, but the bit went crooked on me. I did not hit the threads yet, but I am close. I have called my local machinist and he said he would take a look at it.

I tried the round and square EZ-outs, but they didn't help at all.

Does it look repairable? Have I totally messed this block up? It is a 1978 model, but everything else was going great. ..........

I'm afraid the other head should be removed as well (Just to be on the safe side) and that will leave more broken bolts.......

I'm just not sure what to do. I'm pretty sure I screwed up and I am ready for all of the "you idiot, what did you do that for" replies.....

Is there enough metal left to re-thread these holes ??

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Click to expand...

Excuse me for butting in here but I'd proffer a suggestion to keep in mind for future reference. For these type of situations I take and cut/grind the broken stud down even/flush to the flat surface of the block. I then use a self-centering punch (I have a complete set 1/16" up to 3/4" in graduations of 1/32"). After center punching the top of the broken stud (to assure I am indeed in the very center of the stud) I then use a reverse twist high speed drill bit according to the broken bolt size and drill the depth of the hole (CAUTION: do not overdrill the depth). I then (if still necessary by this point) use one of my easy outs. They are very short in length that requires a socket/ratchet combo or even a boxed end wrench.

Actually I drill the stud down to the point I make slight contact on the threads of the hole in the head, then I use a sharpened long slender center punch to gradually collapse the thin wall of the remaining stud and use a narrow neck needle pliers to peel the thin metal hull that was left out. I then use two different thread taps (a starter and then a bottom) to clean/chase the hole and threads with. The new bolts going back in will receive a thin coating of never seize to prevent future seizing.

In case it matters I'm a 40+ year retired auto tech and broken stud extraction was one of the areas of my expertise.
 
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I appreciate the input! This was my first experience with broken bolts, so as you can see, it was definitely a learning experience.
 
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