Yanmar SB12 in a CD 28

[vandyman4]

As a new CD owner, 1 year next month, I have been absorbing the knowledge on the forum and have found a lot of good gouge.

So, I wanted to come to you guys with a question. I have found a Yanmar SB 12 for sale. I inspected the motor and it is mint. According to current owner it has never been installed...was purchased for a project that never was completed.

The Volvo in my boat runs fine but it is a 30+ year old raw water cooled engine. So I suppose the question is does any one have experience with this engine and what are your thoughts on it as a replacement?

Thanks
Alex

[Ray Garcia]

Our 1981 CD27 has the original raw water cooled YSM8 installed. If the motor is "new", uninstalled, and the price is right, sounds like you have a great find!

I would research getting parts (minor and major) first before you make the plunge. It is hard if not impossible to get some parts for my YSM8. Though ours still runs like a top, eventually I too will need to re-power. I am hoping to put that off as long as possible.

/Ray

[Joe Mac Phee]

Alex,

My 1977 CD-30 ketch was delivered with the YSB-12 engine. It is mounted backwards with Walter v-drive to reverse direction and change the angle of the shaft.

My understanding is that the Yanmar YSB-12 and the SB-12 are different engines. The YSB-12 has a horizontal cylinder and the SB-12 has a vertical cylinder. I would pay careful attention to clearances to mount the SB-12 in your Cape Dory.

If some CD-28's were delivered with Yanmar engines it may be helpful to know which version was used.

The YSB and SB engines are about 30 to 40 years old. I believe that Yanmar parts may be difficult to obtain. However, with cooling water and oil, I feel these engines are very robust and will last a long time.

Joe

[riveredge]

Make sure you test the engine including running it for several hours before you buy it. That's what a Yanmar customer service rep. advised me when I looked at a boat last winter that had a pristine but old Yanmar 1GM10 engine. The engine I looked at may have never been installed in the boat (an estate situation so there was limited direct knowledge.) The Yanmar rep said engines need to be run to keep oil circulating for rust prevention. She said idle engines need special handling to keep oil coatings on internal parts. Otherwise rust can damage or destroy the engine.

[DaveCD28]

The other thing to think about is that your Volvo might keep running fine for many more years, perhaps longer than you own the boat for. Mine is still running strong whereas I know guys that have had to replace thier newer (than my engine) Yanmars. I'm not saying that a Yanmar is less reliable, just saying that you never know.

If you decide to get the motor, I wouldn't necessarily install it right away...maybe just keep it for a backup just in case.

[Ken Cave]

Before installing an engine in your Cape Dory, there are a lot of
issues that must be addressed.

Prop: Which way does the new engine turn. If it is opposite than
your Volvo, you will have to change props.

Mounting the new engine: What do you have to do to install the
engine in the engine compartment? What modifications (fiberglass
etc.) to you have to do before the replacement?

New instrument panel: This is a costly item, and the Volvo panel
will not work on a Yanmar. It will also need to be rewired and
cabled.

Transmission: Does this engine come with its own transmission?
Does it have the proper cables that need to be installed?

Years ago, when my Volvo MD7A finally gave up the ghost, I
had a Volvo 2020 installed by a local shop. All these issues
had to be addressed, and they cost me a lot of money.

Hope this helps

Ken Cave
CD28 #227
Dragon Tale
LaConner, WA

[Klem]

Along the lines of Ken's comments, switching engines involves a lot of "stuff". In my opinion, it would almost never make sense to replace an engine with another engine of the same vintage or even use the other engine as a spare. If you are going to go to the trouble of addressing the issues with replacing an engine with one of a different model, get a new one unless you absolutely cannot.

If you are cash strapped, using your volvo until it no longer works then either rebuilding it or replacing with another engine of the same model probably makes the most sense. Rebuilding these engines is extremely simple and will not be too time consuming. If rebuilding is not something you want to do, running md7a's come up on this board and others with regularity from people deciding they would like a newer engine for various reasons.

If you do decide to move forward with this yanmar, the most likely problems will be rust and dried out seals.

[vandyman4]

Guys, I appreciate all the insight and advice. I am not planning on replacing the engine anytime soon but at $1k I figured the yanmar is cheap insurance. It is ready to drop in with the transmission, instrument panel and wiring harness all there. It is mounted on a steel stand that the owner has run it on from time to time. Yes, I agree with a 30+ year old engine seals drying up and internal rust could be issues. However, my current engine was submerged during Hurricane Katrina so though it runs okay it is suspect. I removed the valve cover and found rust stalactites "growing" under there.

The SB12 is a single vertical cylinder.

[paulmccary]

Alex, at $1k, the Yanmar certainly might be worth buying. But there will be substantial labor involved -- either dozens of hours by you with a lot of specialized tools or by a yard mechanic to install either that engine or another when the time to repower comes.

If you assume that labor and parts at $5k (could easily be more) your old Yanmar will cost $6k installed. A brand new 2 YM 15 out of the box would probably be $7k. So you're not looking at $1k vs $7k. You're looking at $6k vs $12k. And that assumes that you won't need a new prop, hoses, fuel lines or anything else.

So the question is whether you'd want to invest $6k in an old engine with no warranty and limited parts availability. Maybe you would, maybe you should, but it's certainly not a simple choice.