Yanmar V-twin diesel conversion of OMC Saildrive

[Zephyrcat229]

just one quick thought. Have you thought about reinforcing the hull around the saildrive mounting, carbon fiber, kevlar, maybe? If this was me (and I love a new engine!!) I'd go for total overkill where structural integrity is concerned.

I often find overkill is underrated.

[sgancarz]

Originally Posted by Zephyrcat229

just one quick thought. Have you thought about reinforcing the hull around the saildrive mounting, carbon fiber, kevlar, maybe? If this was me (and I love a new engine!!) I'd go for total overkill where structural integrity is concerned.

I often find overkill is underrated.

The original mount appears to have been reinforced quite well when installed. Looks like they went well above the original installation instructions. I don't foresee it going anywhere.

[Jesse]

I noticed you are leaving the existing water pump in place to act as a backup in case the shaft seal leaks. This is a good plan if the pump is designed to run dry. If it isn't it could be a problem. I really like your project and wish you great success.

[Sailmonkey]

Curious if there has been more progress made here?

[sgancarz]

Originally Posted by Jesse

I noticed you are leaving the existing water pump in place to act as a backup in case the shaft seal leaks. This is a good plan if the pump is designed to run dry. If it isn't it could be a problem. I really like your project and wish you great success.

The impeller has been removed and I plan to apply lots of grease to the input shaft seal for lubrication, as my hope is that it will never see water again. However, I figure the seals associated with the original pump should act as a good insurance policy if the lower unit should ever take on water.

[deblen]

Originally Posted by sgancarz

Moving forward on the conversion. So far I have obtained the parts needed to rebuild the lower unit and have been working on the drawings for the mount and coupling.

I have decided that I will use an external raw water pump instead of the internal one in the leg. After doing all of my measurements and drawings, I discovered that I would not have enough room for the outlet of the internal pump. So, I have obtained a used Yanmar raw water pump that I will drive from a pulley attached to the upper portion of the Lovejoy coupling.

I have also completed the design of the exhaust header and mixing elbow. The exhaust will be made from 304 Stainless tubing. I will end up needing to wrap the primary tubes to help keep down temperatures in the lazarette, as it would be too expensive to try and water cool the entire system. So the wet exhaust portion will not start until the mixing elbow.

Interesting project. Too bad one of the outboard mfgrs wouldn't produce a diesel o/b based on this engine type.

This engine is water cooled & from a lawnmower. So how was the fresh water circulated on the lawnmower-is that circ. pump integral to engine?
Are you going to use a heat exchanger & maintain fresh water cooling?

Are you aware of chain couplings--Stronger than lovejoy.

Basically two sprockets face to face with a double chain wrap,but you can buy fancy ones. http://www.baldor.com/brands/baldor-...hain-couplings

Cheers/ Len

[sgancarz]

Originally Posted by Sailmonkey

Curious if there has been more progress made here?

Been working on freshening up the entire lazarette. Been doing lots of scrubbing trying to remove all of the oil from the original two stroke. Once it warms up I plan to repaint the lazarette with a fresh coat of white paint to brighten it up down there.

I have also been doing some re-engineering. I was having issues with the placement of the fuel tank the way the engine was being mounted. The original tank mounted aft of the engine and then there was a 25 gal. water tank forward. I started to think that if I relocated the water tank I would be able to place the fuel tank in its place. However once I removed the water tank I realized that if I just put a smaller water tank and turned the engine around, I could actually keep the fuel tank where it is and I would also have better access to the top end of the engine for maintenance.

So, now it looks like I will need to re-do the mounting plate the engine bolts to, so that I can retain the water pump position on the port side once the engine is turned around.

Here is a pic of the mount in place with the water tank removed and a paper mock-up of the engine sitting on the mount to represent the footprint. Don't mind the grime, I hadn't got to scrubbing this area yet.

[sgancarz]

Originally Posted by deblen

Interesting project. Too bad one of the outboard mfgrs wouldn't produce a diesel o/b based on this engine type.

This engine is water cooled & from a lawnmower. So how was the fresh water circulated on the lawnmower-is that circ. pump integral to engine?
Are you going to use a heat exchanger & maintain fresh water cooling?

Are you aware of chain couplings--Stronger than lovejoy.

Basically two sprockets face to face with a double chain wrap,but you can buy fancy ones. Chain - Baldor.com

Cheers/ Len

Yanmar actually did produce a diesel outboard, but it couldn't be imported to the US, however it was not based on this engine.

The engine does have an onboard water pump to circulate coolant and on a lawn tractor would have had a fan mounted on the flywheel to draw air through a radiator mounted on top of the engine.

I am indeed going to retain the fresh water cooling using a heat exchanger. This is why I am mounting an external raw water pump.

Thank you for the information on the chain coupling. I did not know about the chain couplings, however my choice for the type-s Lovejoy was to help to absorb the torsional shock of the diesel and hopefully prevent it from tearing apart the lower unit.

[sgancarz]

Time for an update!

Spent a couple of hours yesterday removing the rest of the wood from the OMC mount. Originally was going to just sand it until the lower unit would fit and then was going to seal in the remaining wood with fiberglass. Well I couldn't get the lower unit in, so I started chiseling away at the area with a screwdriver. The resin began popping away from the mount. Took me a good hour or so, but was able to remove all of the wood and excess filler.



Once all was out I was able to dry fit the lower unit in the boat.



Felt good to see the lower unit sticking out of the bottom of the boat.



Finished the bracket for the raw water pump today. Tried my hand at TIG welding. Let's just say, I shouldn't quit my day job. Burned through it several times. Had to have a friend fix/finish it for me. It's not beautiful, but it's functional.

It's finally looking like the original drawing.

[Sailmonkey]

Looks good!! I think this will turn out very well for you!


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[Jesse]

I've been looking at your project, and the drawings suggest a possibility of carrying a number of spare water pump drive belts around the upper portion of the lower unit that protrudes through the hull. Possibly secured with wire ties, and an access hole through a side of the mount big enough for your hand to lift one into place after removing the worn belt. This should be easier, faster, and safer than dismounting the engine to change belts. The amount of belts you might carry there would be determined by room available and how they were secured.

[sgancarz]

Originally Posted by Jesse

I've been looking at your project, and the drawings suggest a possibility of carrying a number of spare water pump drive belts around the upper portion of the lower unit that protrudes through the hull. Possibly secured with wire ties, and an access hole through a side of the mount big enough for your hand to lift one into place after removing the worn belt. This should be easier, faster, and safer than dismounting the engine to change belts. The amount of belts you might carry there would be determined by room available and how they were secured.

Both side panels come off, so access isn't a problem. I plan to build a stand this week that will allow me to do a dry fit of everything. This will determine whether there will be enough space between the two shafts to slide a belt in or not. If there is, then changing belts will only mean sliding each half of the coupling up/down in order to pull out the rubber sleeve and slide in a new belt.

If not, I will need to determine the best way to mount a couple spares in as you have suggested.

[sgancarz]

Completed the remake of the pump bracket this evening. My machinist friend felt that once the belt was tensioned and running, the bracket had the potential of bending. So he suggested adding some angle brackets. Unfortunately he didn't come up with this until after the first one was completed.

Anyway, went back to the drawing board and added some additional support. This one should hopefully withstand the test of time now.

[Sailor Doug]

I would be cautious of your choice of a Lovejoy coupling. This coupling is good for angular misalignment but not much radial misalignment. Two of them with a floating shaft (couplings back to back) would be much better. Dodge makes a more suitable bellows style coupling but is much more money. I would be concerned your current design will cause bearing failure and or short coupling life.


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[sgancarz]

Sailor Doug,

Thanks for the suggestion, however I have limited vertical clearance, so I am not able to go with anything other than the planned Type-S Lovejoy. It gives me the most RPM and Torque for its minimal space requirements.

The way I have the mount set up I have plenty of adjustment to be able to align the shafts. With the mount setup and the vertical shaft arrangement, I don't foresee much horizontal movement, but there may be some radial movement which should not affect the shaft alignment.