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  Topic Review (Newest First)
02-27-2009 09:28 AM
Danjcon Thanks for all the great information and encouragement.

I am looking at replacing the entire exhaust system anyway. as well as the fuel lines and water seperator filter, maybe even the fuel tank if I can figure out how to remove the old one.

Most of the problems I anticipate involve the difficulty of removing old parts that have rusted up quite a bit. Especially the coupler. I am not sure about the bearing, since there seems to be some fixture on the outside of the hull that the shaft goes through that I assume contains the bearing.

I need to replace the propeller. Not sure yet about the shaft - it seems like it's in good shape, but I'm not sure how it will line up with whatever engine I go to.

I will probably have lots more questions as I get into this. Thanks for the help everyone.


I've had the boat for only a year, and I am most excited about the years to come having a reliable, adequate sized engine for a boat we really love.
02-27-2009 07:37 AM
1970Columbia34 We are in the middle of a re-power now and doing it yourself is the only way to do it best way to get to know the new motor. you can see pictures of progress at Diesel Conversion pictures by PaperboyRacing - Photobucket

we pulled a old gas palmer p-60 4 cyl gas motor. And are installing a new Universal M25xp. we did have to weld up some new engine mounts to make up of the diffrent angle from the old motor to the new diesel. As well as get a new prop, and prop shaft, Its not a cheap adventure but it will be a great improvement to our boat.

02-27-2009 06:25 AM
Valiente I replaced an Atomic 4 with a rebuilt Atomic 4, thus avoiding shaft and engine mount redos, but I did take the opportunity to replace the entire fuel and exhaust systems, including a basket-style filter on the intake (yes, I have found small fish and weed chunks in there which otherwise would've taken a trip through the block), a fuel/water separator, a fuel line stopcock I can turn off with a boat hook if the engine was on fire, and I got rid of the waterlift muffler (it was junk and a sort of much grief), and installed a Vetus waterlock, which has been flawless. Add a new, smaller gas tank (Tempo) and bigger vent lines with new double SS hose clamps everywhere, and it was surveyor-ready.

In other words, if you're getting a new engine, make sure all of the existing parts are worthy of the expense. I did everything listed above, and it was, aside from a few contortions and the need to work by feel in spots, relatively easy and a big confidence booster. My engine maintenance is about three hours a year, and it starts every time.
02-26-2009 11:11 PM
Perithead I have never repowered a boat myself, I am more of a carpenter than a mechanic. Although, I have a few websites that may help you, one is a great detailed documentation of an owner repowering his sailboat. Looks like he did a great job too.

You can find it at my website in the Sailboat Projects section, just scroll down to the engines and fuel links and check them out.

Good luck and don't skin your knuckles up to bad!
02-26-2009 10:46 PM
Me, too

I also replaced a Volvo MD7A with a Yanmar 2GM20F. I took most of the old block out myself, and then paid someone to put the new block in place, hook up the transmission and align it, and install the new dripless shaft seal. That sounds like a lot, but it left installation of the new fuel tank, the control panel, all the filters, the exhaust, the plumbing and electricity to me. Saved a lot of money, and taught me all the details of the engine.
02-26-2009 02:45 PM
jbondy Confirm the existing exhaust system is right for the new engine. Back pressure is imortant. Too much and you can kill an engine.

Our PO had repowered from an A4 to a Yanmar 3GM30. He kept the original raw water intake and exhaust system. The engine died due to undetermined causes. We repowered with a 3YM30. When I brought it to the distributor to go over the installation, he noticed that the exhaust system was too restrictive (1.5" as opposed to 2.5") and determined that was the cause of the prior engine's demise. The raw water intake as also too small (1/2" as opposed to 5/8"), but that was OK.

Anyway, assume nothing!
02-26-2009 02:28 PM
From a Volvo MB10A to a Yanmar 2GM20F

Hi there.

I took the Volvo gas out of our Tanzer 28 and installed a new Yanmar 2GM20F. I did 95% of the work myself with tons and tons of good advice and lots of help from friends.

Thoughts and comments:

1 - I am NOT a mechanic (I took band instead of Industrial Arts in school) but am not afraid to try things.
2 - I took my time and at the time our Tanzer 28 was in our driveway - so I could work at my leisure and did not have far to go to work after supper.
3 - I needed a new prop
4 - I also needed a new prop shaft (but did not know it at the time - would have worked except the original was 25mm and not 1 inch - soooo close)
5 - the fuel tank was behind the engine and came out very easily. Painted it, cleaned it , re-plumbed it and it worked just fine
6 - I got help in aligning the shaft to the engine
7 - I took help in the final set up
8 - the old one came out easy and is quite light when taken out in pieces; fly wheel, transmission, block.
9 - the new diesel was lighter than the old gas engine.

and - it worked just great.

The big big bonus was not the major savings in labour costs, but rather, the confidence that I developed and the intimacy I developed with the new engine. I was ready for just about anything that came along in the next six years we had the boat before we sold her and got a bigger boat.

Would I do it again - yes, in a heartbeat!

For what it is worth - I do have photos if you think they might be of use????

02-26-2009 09:43 AM
r.furborough Dan

Regarding the exhaust being on the opposite side of the engine, if you are using flexible rubber hose for a wet exhaust system then it's not too much of a problem, plus it is always possible to have an exhaust elbow that directs the exhaust over to the opposite side to help with this. I know Beta can offer this option.

02-25-2009 10:16 PM
Danjcon Thanks,

I know that I will have to move the exhaust to the other side, and I will have to replace the propeller and shaft as well. I need to check about the throttle.
With a tight space, I am looking forward to easy access to most of the maintenance items.

02-25-2009 09:31 PM
Go with the Beta

I repowered with a Beta 37.5 hp four years ago and it went very smooth. There were a couple of minor things that I had to worry about like the throttle linkage was backward and in moving it around to work from the other side I had to extend the air intake.

Stanley at Beta NC is a great guy to work with and the engines are super smooth and quiet and they're really Kubotas so parts are easy to find and are reasonably priced.

As far as how easy it is overall. The folks at Beta will send you a drawing showing the installation and you must approve it before they will send the engine. I went back and forth with them three times before it was all correct to my satisfaction and as a result everything fit perfectly.
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