Rebuilding Tortuga - Removing the Chrysler Crown Engine

The engine in the boat is a 110 h.p. Chrysler Crown flathead 6 gasoline engine with a mechanical gear.  Checking through the documentation that came with the boat, the engine appears to be a 1950 vintage M47s that was installed in the boat in February 1952 about 2 weeks before I was born.  When I first looked the boat over, it was clear that all was not right with the engine since I could not turn the engine at all by reefing on the flywheel.  Also, I couldn't turn the prop at all with the gear in neutral.  when I visited the boat for the second time, I was able to slightly budge the prop, but again failed to turn the engine at all despite applying a couple of undered foot pounds of torque to the flywheel.  The previous owner said the engine was running in 2004, but the three year layup obviously wasn't good for it.

Because of the condition of the engine we decided to repower the boat with a smaller diesel.  Repowering will get rid of the gas on the boat and lighten the boat.  In addition, because a 40-50 h.p. diesel is so much smaller than the 925 lb Chrysler Crown, a small diesel will fit under the cockpit platform, which will let me get rid of the engine box.  a 50 h.p. diesel is also much shorter than the Crown, so the engine will not protrude into the main cabin.  All of that will let me move the cabin entrance from the starboard side to the center.  That will make my wife happy since I can make the steps wider and the bottom of the steps will be on the flat of the cabin sole, not at the slope of the bilge like it is now.

Finally, removing the old engine will open up the main part of the hull that needs repairs by giving me access to the floors and frame ends that are now under the engine.  Also, getting the 900+ pound behemoth out of there will significantly decrease the strain on the hull, which will make me feel better when I start removing planks and frames.

Sept. 25, 07 - The first step in all these changes is to get the old engine out.  Needless to say, I can't do that myself.  So I have hired a local boat shop (Bass Harbor Boat) to do the job.  They will move the boat to their shop, pull the engine and then put the boat back in my yard.

To save money, I started the job by disconnecting the engine.  That mostly consisted of disconnecting wiring, plumbing, the fuel line, the alternator and the exhaust.  All of those went fairly easily and only took about 1.5 hours.  I also broke out all the nuts on the engine mounts so they would be easy to remove when the time came.  Then I moved on to the harder parts.  First I disconnected the throttle and choke cables.  They were a bit tough because of access and corrosion, but both came off in about 20 minutes.

The next job was to disconnect the prop shaft from the transmission coupling.  The 1-3/8" aquamet shaft when into a flange with six 1/2" bolts.  The bolt heads barely protruded enough for me to get a socket onto them and the nuts could only be turned about 1/8th turn at a time.  Despite that the three bolts on the top of the flange came out quite easily.  The clearance between the flange and the hull made it impossible to get the wrench on the nuts on the bottom three bolts, so I had to turn the shaft 180 degrees.  First I made sure the gear was in neutral.  Then I got out of the boat and tried to turn the shaft with the prop.  I reefed on the prop until I could feel the shaft flexing, but failed to turn it even one degree, let alone 180 degrees.  So I went into the shop and brought out my biggest pipe wrench and a cheater bar.  I put the pipe wrench on the flange, slipped the cheater bar onto the wrench handle and started leaning on the bar.  I had nearly my entire weight on the bar, applying 800-900 foot pounds of torque, before the shaft started to turn, but turn it did.  After the first 10 degrees or so the shaft started turning more freely and I took the cheater bar off.  I was then able to turn the shaft by simply standing on the pipe wrench handle (say 200 foot pounds of torque).  After several resets of the pipe wrench I was able to turn the shaft the required half turn and the remaining three bolts came out easily.  A little prying with a screw drived separated the shaft flange from the gear glange and I was done.  incidentally, the prop turns quite freely now that it is disconnected from the gear.  I figure the oil in the gear must have transformed into some sort of tar like substance over the years.  Given the torque it took to rotate the gear in neutral, there is no way the engine could have turned it since the maximum torque output of this engine is only supposed to be about 210 ft-lbs.

The final thing that needed to be disconnected was the shift mechanism attached to the gear.  The gear shift on this boat is a bronze handle that is attached to a vertical bar.  To put the gear in reverse the handle is pulled up about a foot above the neutral position.  Similarly, pushing the handle down about a foot from the neutral shifts the gear into forward.  The vertical bar  the handle is on attaches at its lower end via a pivot pin to an approximately 5 foot long steel flat bar.  The flat bar has a 1" diameter steel rod welded to it at a right angle about 3 feet from the forward end.  The end of that rod is attached to the shift shaft on the reversing gear via a 2" diameter steel coupling. The steel rod is also supported by a plate it passes through, so that moving the forward end up or down pivots the rod and shifts the reversing gear.  At the aft end of the flat bar the rod is welded to there is a counter weight made up of about 30 pounds of lead.  Disconnecting this massive shift mechanism is nominally easy in that all you have to do is back out the set screws that attach the coupling to the end of the gears shifter rod and the shift mechanism rod.  Well it should have been easy, but 55 years of corrosion had oblierated the set screws and turned the entire coupling into a mass of rust.  Sawing through a 1" steel bar isn't very tough if you can use a sawzall or similar power tool.  However, because the fuel valve to the carb had been left open for the three years the boat was laid up, the entire engine space reeked of gas from the fumes that had escaped from the carb over the years.  Consequently, I was reluctant to use a power tool.    So I got the hack saw out and started sawing through the 1" diameter steel rod just outboard of the coupling connecting it to the gear.  The job was made rather unpleaseant be the fact that the location of the rod only allowed the saw to be moved about 3" on each cut.  At any rate, about 1,000 cuts later the steel bar parted and the engine was disconnedted from the boat except for the engine mounts.


Here is the disconnected engine.  Just below the exhaust you can see the transmission shift coupler that I sawed through.  This picture shows how big this engine is.  It measures nearly 58" long and is 25" wide.  The diesel I plan to replace it with is about 32" long and less than 18" wide.

The engine is now ready to remove.  I will take pictures of the process when the yard does it.

Oct. 2, 07 - Today the hauler picked up the boat and hauled it over to Bass Harbor Boat.  After they blocked the boat, I went aboard and unbolted the motor mounts.  The plan is to pull the engine later this week.  I should have the boat back home early next week.

Oct. 8, 07 - Today I went over to the yard to work on the cabin house top.  When I got there I saw a big tarp behind the boat.  I turned back the tarp and found the engine out of my boat.  I had hoped to be there for the removal, but missed the event by about an hour.  At any rate the engine is out, now all I have to do is get rid of it.

The Chrysler Crown Engine sitting behind my boat

Where the engine used to be

The next steps are to remove the old engine beds and clean up the engine compartment.  After that I will start replacing floors and frames.