Yanmar SD20 seawater intake valve

[chris in SG]

I had my Yanmar 3YM30 engines and saildrives overhauled almost 10 years ago (seems like yesterday) and they have been mostly trouble-free. The mechanic who did the overhaul in Singapore did not touch the seawater intake valves which I had already noticed were jammed open. I queried why he had not added the cost of new valves to the bill and he was a bit evasive (which was unusual, for him) so I grumbled mildly and let it go.

More recently I've had trouble with weed and plastic getting stuck in the right-angle bend of the valve. I have tried and failed to remove the valves with a wrench, partly because I'm scared the valve body might break off, leaving the threaded portion inside the saildrive body [I'm doing this on the hard, but it would still be a disaster if it breaks off].

This got me thinking - maybe the mechanic was similarly scared of this happening, since it would have seriously eaten into his fixed price for workmanship.

Does anyone have any similar experience or recommended solution?

[skipperpete]

I’ve never broken one off but it is a possibility due to the awkward angle. You need a tool thats crooked enough it will give a decent angle, strong enough to do the job but still compact enough to fit in the work area…. Those yanmar valves are bloody tight

[ggray]

I have no trouble removing the valves from my two SD20s, but they have never been in place for more than 3 years before I remove them. Usually every other year. Yours may be difficult to remove now, but it would seem to me that since you are hauled, now is the time to fight that battle. You need a valve that can be shut off! What would you do if the hose burst, or you have to replace or rebuild the water pump? I use a big adjustable wrench to remove them.

I remove mine at every haul out, and clean and exercise with WD40 (counting the turns) and lubricate (Fluidfilm) each thoroughly. At how much those things cost, worth caring for. One lasted 20 years, the other 22 years (I just repalced that one this Spring). They both still worked, but not as freely as I'd like. I've heard folks say they don't last but 5 years or something like that. Wonder why....

[chris in SG]

Originally Posted by ggray

I have no trouble removing the valves from my two SD20s, but they have never been in place for more than 3 years before I remove them. Usually every other year. Yours may be difficult to remove now, but it would seem to me that since you are hauled, now is the time to fight that battle. You need a valve that can be shut off! What would you do if the hose burst, or you have to replace or rebuild the water pump? I use a big adjustable wrench to remove them..

I've "survived" because the seawater strainers are above the waterline and the valve itself is maybe 6" below the waterline, so the pressure is low. I've removed the hose when attempting to clear blockages in the valves and I've replaced both Johnson pumps which, of course, are 'downstream' of the strainers.

Nevertheless, your advice is well-taken. There's no excuse for poor maintenance. Thanks for the helpful advice.