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Yanmar 2GM20F:  Installation, Alignment, and Hookups
This page was last updated on 8 August 2001.

TUESDAY 7/31/01

After spending the morning preparing the engine beds and using my template to properly set the mounts for the engine alignment, I drove home to pick up the new Yanmar.  Back at the yard, I reversed the process used to get the old SB12 out of the boat, and swung the boom out over the side so I could hoist the engine out of my truck and into the cockpit.   This went smoothly, even though I was "performing" in front of the lunch crowd at the nearby restaurant.  As before, I set the engine in the cockpit well, then moved the hoist forward and raised the engine up to the bridgedeck.  Here I paused, and installed the four flexible engine mounts in their proper positions.  I had marked them before when I was using the template to get the rough alignment right.

Setting up the hoist one final time, I swung the engine through the companionway, and lowered it down towards the engine room.  It was easy to move it as required, and soon I had it nearly sitting on the beds.  As I lowered, the forward mounts came into contact with the beds first, to help me keep things in position I partially installed the two forwardmost lag screws on the forward mounts.  Then, I continued lowering the engine until the after mounts were resting on the engine foundation.  Note that I had removed the alternator for two reasons:  to make it a little easier to get the engine in place (without the alternator projecting from the side) and I am replacing the stock alternator with the high capacity large-frame alternator I used on my other engine, and around which my electrical and charging systems are constructed.  The 55-amp alternator that came with the engine would be fine, but it is internally regulated and therefore incompatible with my external smart regulator.

With the engine sitting squarely on all four mounts, I installed the lags and partially threaded them in.  I removed the hoist and cleared things out a bit to give me room to work.  I made sure that the engine was in the proper place, and that the mounts were all lined up with the engine--it's easy for them to get cockeyed a bit.  I needed a little crowbar persuasion to get the aft port mount properly aligned so I could install the after lag screw.  Then, I tightened down all the lags, leaving them only slightly loose so I could move the engine if necessary to affect the alignment.

Moving into the cockpit, I reached through the access hatch there and pulled the shaft forward to check the rough alignment.  The couplings thunked together nicely, indicating that the alignment was very close.  The side-to-side and up-and-down alignment seemed spot on, so all I had to worry about was the fine face alignment of the couplings.  Using a feeler gauge, I checked the coupling alignment all the way around, and made some small adjustments to the engine.  It didn't take much--the alignment template is worth its weight in platinum, and is certainly worth the effort required to build it.  Then, I cranked down all the lags, and tightened the adjusting nuts on the mounts.  I'll check alignment again once the boat is in the water.  Cranking down the lags required several transmogrifications of my 1/2" ratchet, including long and short extensions, and no extensions at all, because of the tight access in some locations.  My arms were certainly tired afterwards.  

With the mounts secured, I moved on to install the new Yanmar flexible coupling (Part # 104214-05450) and attach the shaft to the engine.  I used the new flexible coupling in place of the Drivesaver I had previously on the recommendation of my engine supplier--the new one is two slabs of steel surrounding a heavy-duty rubber core.  This absorbs the movement of the engine (the result of the flexible engine mounts) and will also serve as a sort of "circuit breaker" should the propeller come into contact with an immobile object--breaking the coupling instead of the transmission.  The flexible coupling features studs on each side, and I secured it first to the transmission coupling, then secured the shaft coupling and shaft to the other side, using nylock nuts.  Working upside down through my (thankfully) large cockpit hatch, securing the eight nuts took over a half hour, leaving me feeling woozy.  

Note that the photos shows my half coupling and flexible coupling after I repainted them; the red color is not standard.

As I still had some time left in the day, I spent some of it reattaching the exhaust hose to the engine.  Using the same length of hose from the old engine, I determined a new route for it from the riser, down to starboard of the transmission, and then forward to the Vetus Waterlock in the bilge beneath the engine.  This is a more direct--and more convenient--route than the hose had to take with the old engine, and I was able to cut about 12" off the hose.  I secured it to the riser and Waterlock with double clamps.  I also reinstalled my raw water strainer, and attached the short length of hose needed to run from the strainer to the inconveniently-located raw water pump on the engine.  (It's located on the back side of that pulley above the strainer--meaning that changing the impeller should take about 9 times as long as it should.  This seems like poor design--I wonder why they did it this way?)

This done, I called it quits for the day, knowing that I was ahead of my initial aggressive schedule.  Things were going very well. 

Please click here to continue the project--final hookups of the fuel and electrical systems, and the cooling system.

 


Glissando, Pearson  Triton #381
www.triton381.com 

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