Engine Flush?

[tjr818]

First let me point out that this engine has probably always been run in fresh water. I know it has only been in fresh water for the last seven years, at least. After too many years I have finally been able to remove the zinc from our YSM8, it was completely encrusted with lime deposits and rust, but otherwise seems to be the original shape and size. That led me to wonder about flushing the cooling system. Should I do it? Should I leave well enough alone, since there have been no cooling problems? If I should, what product is recommended?

[Sea Hunt Video]

Tim:

If you make the decision to flush your Yanmar I would recommend "Rydlyme".

http://www.apexengineeringproducts.com/ ... dlymehome/

The Yanmar mechanic I swear by used it to flush out my 30 year old Yanmar 1GM that was overheating at the most inopportune moments. I think it took about 2 hours but she has worked flawlessly since. It is a simple process to flush.

Now, whenever I haul out or sooner I just attach a freshwater hose to the raw water intake and flush the system for 20-30 minutes with fresh water. Seems to work OK. Unless I replace the Yanmar 1GM I will probably flush again with Rydlyme in a year or so.

[Northstar1014]

Dont know much about engine flushes, but if I were in your shoes my biggest question would be the condition of the heat exchanger and the exhaust elbow. There was a recent article I believe in Good Old Boat about a Yanmar shutting down underway because of a rust clogged exhaust elbow.

On my Westerbeke, you can pull the end off the heat exchanger and inspect the copper exchanger tubes for broken pieces of the zinc and salt.

MaineSail has written about it:

http://www.pbase.com/mainecruising/heat_exchanger

Good luck