Yanmar YSM8- Too Much Thumping ?

[Jeff Schmoyer]

Well, I knew this Yanmar 1 cyl engine was reputed to be noisy, but ...gosh! After my first summer of sailing my 'new' '78 CD27, I think I have to check the fillings in my teeth, because that engine sure does shake and thump. It's pronounced even at the bow, especially at idle with transmission neutral. Shifting into gear actually reduces thump and shake.

Boatyard has advised replacing the motor mounts. But will this really help? Anybody do this and get a big imporvment? What about the diesel analog to the tune up- is vibration and thumping a sign of anything?

Several have re-powered their cd27 up to the Yanmar 2-GM. But when I asked an engine guy at the boat show for a quote he actually told me: "nah, no need that thing will run forever" (well 5 grand w/out labor if I must know!). See, the only problem is- that lovely lil' thing really might run forever!

And you know, the irony is she doesn't really seem that underpowered. Granted I do have a 3-bladed prop. and I haven't tried to buck winds over 30kt yet, but this engine seems to give me hull speed in the (admittedly benign) conditions I've been out in.

Jeff



jeff.schmoyer@iff.com

[yves feder]

Well, I knew this Yanmar 1 cyl engine was reputed to be noisy, but ...gosh! After my first summer of sailing my 'new' '78 CD27, I think I have to check the fillings in my teeth, because that engine sure does shake and thump. It's pronounced even at the bow, especially at idle with transmission neutral. Shifting into gear actually reduces thump and shake.

Boatyard has advised replacing the motor mounts. But will this really help? Anybody do this and get a big imporvment? What about the diesel analog to the tune up- is vibration and thumping a sign of anything?

Several have re-powered their cd27 up to the Yanmar 2-GM. But when I asked an engine guy at the boat show for a quote he actually told me: "nah, no need that thing will run forever" (well 5 grand w/out labor if I must know!). See, the only problem is- that lovely lil' thing really might run forever!

And you know, the irony is she doesn't really seem that underpowered. Granted I do have a 3-bladed prop. and I haven't tried to buck winds over 30kt yet, but this engine seems to give me hull speed in the (admittedly benign) conditions I've been out in.

Jeff

If the motor mounts are really dodgy, it should make quite a difference Jeff. I recently acquired a '77 CD27 with the same engine, and yes the vibration is greatest at idle, but apparently not as bad as you're experiencing. Under gear it's really not bad at all, in fact, for comparison it is LESS than I had with a 2 cyl Volvo MD2 in my 30' Arpege - and that was well mounted, with a flex shaft coupling!

Actually I'm very impressed with 1 cyl Yanmar and with decent maintenance it's terrific I think.

Good luck - $5,000 will buy you a lot of canvas! :)
Yves



diesel@tinyradio.com

[Bill]

Well, I knew this Yanmar 1 cyl engine was reputed to be noisy, but ...gosh! After my first summer of sailing my 'new' '78 CD27, I think I have to check the fillings in my teeth, because that engine sure does shake and thump. It's pronounced even at the bow, especially at idle with transmission neutral. Shifting into gear actually reduces thump and shake.

Boatyard has advised replacing the motor mounts. But will this really help? Anybody do this and get a big imporvment? What about the diesel analog to the tune up- is vibration and thumping a sign of anything?

Several have re-powered their cd27 up to the Yanmar 2-GM. But when I asked an engine guy at the boat show for a quote he actually told me: "nah, no need that thing will run forever" (well 5 grand w/out labor if I must know!). See, the only problem is- that lovely lil' thing really might run forever!

And you know, the irony is she doesn't really seem that underpowered. Granted I do have a 3-bladed prop. and I haven't tried to buck winds over 30kt yet, but this engine seems to give me hull speed in the (admittedly benign) conditions I've been out in.

Jeff

If the motor mounts are really dodgy, it should make quite a difference Jeff. I recently acquired a '77 CD27 with the same engine, and yes the vibration is greatest at idle, but apparently not as bad as you're experiencing. Under gear it's really not bad at all, in fact, for comparison it is LESS than I had with a 2 cyl Volvo MD2 in my 30' Arpege - and that was well mounted, with a flex shaft coupling!

Actually I'm very impressed with 1 cyl Yanmar and with decent maintenance it's terrific I think.

Good luck - $5,000 will buy you a lot of canvas! :)
Yves

Jeff

I have a 25D with the yanmar 1GM (7.5) and at idle it to knocks pretty good. When I first got the boat I thought it was excessive, so I bled the system, changed filters and tried it again.. bleeding the system really reduced the knock.

I also replaced engine mounts, not because of the knocking, but because they were worn out. I cant really tell that they stopped any vibration at all.

If I remember correctly, my manual says that bleeding the system is a "cure" for knocking. I cant remember s$#% however, and could be wrong about that.

Good luck

Bill



cd25d@rhapsodysails.com

[bob loewenstein]

My CD27 doesn't thump around except a low idle. When motoring there are actually some very quite places over some broad rpm ranges; surpisingly quiet for a 1 cylinder. At max it's audibly noisy, but not much vibration.

Does the vibration occur at all rpms?

Have you checked your shaft alignment? If it's as bad as you make it sound, there could be some imbalance somewhere.



rfl@yerkes.uchicago.edu

[Jeff Schmoyer]

Gentlemen,

Thanks for your comments. You've given me much encouragement that with proper care, this engine can stay. My wife thanks you even more than I do!!!

I'll report back regarding fuel filter next week. Maybe to mounts in spring.

Anybody do the fuel injector cleaning procedure that's (poorly) described in the manual? What are the indicators that one has to overhaul this aspect of the engine.

jeff





Jeff.Schmoyer@iff.com