The Rusty Bolt Nightmare

Long time no post!  I have been busy working on the engine and the interior of the boat, but am in limbo on a lot of projects.  Writing about a project while it is not complete is frustrating to me, it is much easier to write once something is complete so I can tell my lessons learned and whatnot.  Without a whole lot to report these days since I am in the middle of a lot and finishing nothing...writing has been stale.  Here is a tidbit of a frustrating piece of the engine rebuild... One of  the most frustrating and difficult things about rebuilding the engine (and the boat as a whole) has been rusty/corroded bolts & screws.  Make the bolt hard to access, and it is even more difficult.   A primary job I have put before myself in this engine rebuild is to make sure all rusted and corroded bolts are removed and replaced while the engine is out of the boat and I have easy access to all angles of the engine.  I do not want to be stuck in some muggy anchorage in the middle of nowhere struggling to remove a fully corroded bolt to replace an engine part...might as well get it done now so repairs are easier in the future.

Unfortunately, there were quite a few of these trouble bolts, and they have caused me a lot of grief.  I've learned a lot of tricks to get them out: using the correct wrench (six sided > 12 sided), breaker bars, penetrating oil, heat, vice grips, etc.   Though along the way I have become quite adept at getting most of them out, one set of bolts in particular had given the business.  The bolts in question are those that hold on the exhaust elbow onto the exhaust manifold:

They were easy enough to access, but they were absolutely corroded throughout. Since the heads were corroded down, the correct size wrench wouldn't even fit on them anymore.  I quickly had to resort to vice grips, but no matter how tight I got them and how much leverage I was able to get, these things didn't turn at all.  I sprayed the bolts with penetrating oil twice a day for about a week before trying again.  I tightened the vice grips as hard as possible and put on an extra long cheater bar for maximum leverage.  When I started on the first bolt, I thought I saw a small bit of rotation so I kept applying pressure.  Sure enough, rotation was afoot!  Unfortunately, that was the bolt head breaking off from the bolt.  This happened with 3/4 of these bolts, only one of them successfully coming off.

I was left with this:

From here I did some research on what to do next.  While I pondered my course, I straight up soaked these bolts in penetrating oil for about two weeks.  I figured with such a long soak, they were bound to come out somehow.

After soaking for a long time, I figured I would try to cut a slot in the bolts with my Dremel tool and use my impact driver to turn them out.  You can see in the top left bolt in the prior picture I had tried this before the oil soak, but it wouldn't budge.  So after two weeks of soaking, I went at it again only to break off the remaining pieces of bolt.

So by now I had tried everything I could think of with no luck.  Many people would suggest using left handed drill bits or an Easy-Out to turn them out.  After speaking to some people who have used that technique before... I decided that was a horrible idea.  If these bolts were truly rusted in place, the Easy Out would just break off in there and create an even bigger problem.

The last resort was to drill out the bolts and use a Heli-Coil or Timesert treaded insert.  I was quite ready to go this route, as many people had nothing but positive things to say about each product.  However, I became quite anxious about the precision needed to drill straight down the center of these small bolts.  Without a large drill press, getting a perfect center drilled in the bolts seemed nearly impossible.  I contemplated using a center punch and drill guides, and even practiced on a few other bolts.  However, I could never get it right.

If I screwed this up, I could end up drilling a hole in the wall of the heat exchanger and ruin the whole unit..and a new one is not cheap (list for $2k+!).   For the first time in this entire rebuild, I threw in the towel and decided to seek professional help.

I took the whole unit to a machine shop near me and asked if they could do the job, and they said it wouldn't be a big deal at all.  Since there is risk of drilling into the wall of the heat exhanger, and the fact that it is aluminium, they decided using stainless Heli coils were the best bet.

I just got the unit back and they did a great job.  Back to the rebuild...