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Okay, I thought i would share this because i saw a post (before i registered on the site) of a gentleman who did some "preventative maintaince" on his powerhead only to make things worse by breaking a headbolt off flush with the block. I can't tell you how many times I have done that very same thing, especially with these saltwater used outboards.
I came up with what I think is a pretty good solution, but I won't be able to post how it worked out because I am not quite finished with the job.
I broke three!!head bolts from my 89 yami 200hp two weeks ago. Luckily for me, they were all in the center portion of the head, so they are all accessible to drill out (none below the pan level)
I think that the hardest part of these types of jobs is how to keep the drill bit centered on the ss bolt, without it wanting to walk into the aluminum and messing up the threads, really making matters worse. Once you can get the bolt center-drilled, you can try to get it out or drill it further and then just use a helicoil. Just don't make things worse by breaking off an easy out in the first hole you drilled. Hopefully I drilled my in the center...Here's how i did it.
I dont have the head off yet, so I'm not 100 percent positive I got it centered, but I saw NO aluminum chips...a good thing.
I decided to use the existing head as a guide. The hole in the head is obviously way too big to be used as a guide as is, so the idea is to put in some concentric tubing to make it effectively smaller, and still be able to keep the drill bit centered.
I found and cut off a piece of brass tubing just smaller in diameter to the cylinder head bolt hole with little play. I then used a layer of masking tape on the outside of the tube to take up the rest of the play and ensure the tube was pretty well centered (almost exactly I would say). I found a smaller piece of tubing to go inside of that one and fit loosely enough to allow it to spin, but still remain centered within the first tube. Then I got a drill bit that fit inside the the second tube, about 3/4ths the size of the bolt diameter and used my guide tubes to keep me centered. (The diameter of the second tube narrowed the hole down to about the size of the drill bit used). About 15 minutes and a lot of lube later, I was thru the first bolt.
I kept cleaning out the hole and checking the chips with a magnet to be sure I got nothing but steel. This process seemed to work as i made it thru all three bolts (broken flush with the block) using the same cheap drill bit from walmart (set of about 20 for 6$). Now, (all?) I have to do is finish removing the head, and hope that somehow I can remove those studs. They have been soaking with wd40 for a week now. Also, I thing I drilled dead center but like I said, i will post my results after i see it without the head on. This time, if I get the bolts out, i will be using antiseize. I had that same head off the powerhead less than 2 years ago, and already, the corrosion set in! Probably had a leaky head gasket too as i didnt use a new one at the time (another story).
Any further Ideas on how to proceed would be welcome. I am hesitant to use an easy-out because I have NEVER used one successsfully and I always made things worse by breaking them off in the drilled out bolts.
This forum is very good. I hope it continued to grow as the information here is INVALUABLE!..Thanks for reading.
Sam
I came up with what I think is a pretty good solution, but I won't be able to post how it worked out because I am not quite finished with the job.
I broke three!!head bolts from my 89 yami 200hp two weeks ago. Luckily for me, they were all in the center portion of the head, so they are all accessible to drill out (none below the pan level)
I think that the hardest part of these types of jobs is how to keep the drill bit centered on the ss bolt, without it wanting to walk into the aluminum and messing up the threads, really making matters worse. Once you can get the bolt center-drilled, you can try to get it out or drill it further and then just use a helicoil. Just don't make things worse by breaking off an easy out in the first hole you drilled. Hopefully I drilled my in the center...Here's how i did it.
I dont have the head off yet, so I'm not 100 percent positive I got it centered, but I saw NO aluminum chips...a good thing.
I decided to use the existing head as a guide. The hole in the head is obviously way too big to be used as a guide as is, so the idea is to put in some concentric tubing to make it effectively smaller, and still be able to keep the drill bit centered.
I found and cut off a piece of brass tubing just smaller in diameter to the cylinder head bolt hole with little play. I then used a layer of masking tape on the outside of the tube to take up the rest of the play and ensure the tube was pretty well centered (almost exactly I would say). I found a smaller piece of tubing to go inside of that one and fit loosely enough to allow it to spin, but still remain centered within the first tube. Then I got a drill bit that fit inside the the second tube, about 3/4ths the size of the bolt diameter and used my guide tubes to keep me centered. (The diameter of the second tube narrowed the hole down to about the size of the drill bit used). About 15 minutes and a lot of lube later, I was thru the first bolt.
I kept cleaning out the hole and checking the chips with a magnet to be sure I got nothing but steel. This process seemed to work as i made it thru all three bolts (broken flush with the block) using the same cheap drill bit from walmart (set of about 20 for 6$). Now, (all?) I have to do is finish removing the head, and hope that somehow I can remove those studs. They have been soaking with wd40 for a week now. Also, I thing I drilled dead center but like I said, i will post my results after i see it without the head on. This time, if I get the bolts out, i will be using antiseize. I had that same head off the powerhead less than 2 years ago, and already, the corrosion set in! Probably had a leaky head gasket too as i didnt use a new one at the time (another story).
Any further Ideas on how to proceed would be welcome. I am hesitant to use an easy-out because I have NEVER used one successsfully and I always made things worse by breaking them off in the drilled out bolts.
This forum is very good. I hope it continued to grow as the information here is INVALUABLE!..Thanks for reading.
Sam