Originally Posted by Dulcesuenos
We have hauled relaunched many times and never an issue not closing the valve. Not being able to close it is handy if you need to service the strainer or raw water pump
at sea or in the water.
AS for Zincs on the yanmar SD20 there are No zincs on the engine or the drive except for the zinc at teh front of the prop. The manuakls are all wrong, not sure why they drew them their.
Maybe you haven't found the anodes yet? How long have you had the engine?
If yours is a heat exchanger
engine I can't advise but:-
My Yanmar raw water
cooled 1998 2GM
20 SD has a zinc in the block on the exhaust
side, another zinc at the rear of the cylinder head
, and another zinc on the right hand side looking aft in the water passage
from the sail drive intake. They are all accessed by unscrewing large about 1" hex plugs. The zincs are rods about 1,1/2" long by about 1/2" dia. screwed into the inside of the hex plugs. The hex plug in the block side is a taper thread and the other 2 have copper washers. The one at the rear of the head
is easy to overlook but it's there.
I put a smear of grease on the threads of the anode hex plugs to prevent them corroding in place. It also prevents salt
deposits bleeding to the outside. A fairly long 1/2" drive bar and socket are best to remove the anode housings.
Also of course the prop anode which has been redesigned in the last year or so as two pieces, made of aluminum
alloy. It's no longer necessary to remove the prop to change it.
I have the bronze type of shutoff valve for the raw intake that takes around 18 part turns to open fully. I always close it when the boat is not in use. I also regularly spray some lanoline around the engine and on that valve. This gets inside the barrel and keeps it free. Keeping using it also keeps it free.
A neighbouring vessel has the same motor
and the owner says he never closes the water intake and he can't now as it's stuck in open. Imagine it's just salt
deposits and some gentle work could free it. A bit of WD40 and some working with a 10" crescent on the T should do that.
There is a replacement shutoff lever type valve available but I've found no need to change it.
Caution. There is an oil
line from the right hand side (looking aft) of the block running around and under the zinc anode plug behind the cylinder head. The oil
line supplies the valve rocker gear
in the head. When changing that anode, some sea water inevitably dribbles over that painted steel
oil line. I also spray that oil line with lanoline and check by hand for corrosion
. I have replaced it once as a precaution as it had some pitting.
If your Yanmar is raw cooled and has no zinc anodes maybe it's a Chinese copy....Are your manuals
written in Chinese? Sorry just kidding.