Yanmar Saildrive seacock

[TSweather]

Yes, this has briefly discussed here before, but this thing broke again and I'm interested if anyone has found an upgraded solution for this critical part that lasts and doesn't require 10.5 turns to operate?




The older part number: Yanmar 196420-02290 has been superseded by Yanmar 196420-02291 which is seemingly identical.

These are lasting only 2-3 years at best in the fresh water of Lake Erie before becoming so hard to turn that I need to use a 1/4 deep socket and extension to give enough leverage to turn the valve. Inevitably one of the ears on the handle breaks off and I'm again left looking for a replacement. Has anyone found a high quality half turn ball valve with the correct threads that fit?

[Vento Solare]

Todd,

I've been thinking about doing the same thing for a few years so your post prompted me to do some research. I would suggest either a dezincified marine bronze (DZR) or Marelon setup for replacement. If you are able to remove the existing Yanmar valve and could check the saildrive threads (e.g. 1/2" NPT which is tapered), I could make a better determination on part numbers.

The parts for a Marelon approach would require:

1/2" Threaded Nipple Male to Male
1/2" Inline Ball Valve
1/2" 90 degree elbow (1/2" Threaded to hose barb - I think the hose is 5/8")

If Marelon is used for the valve and hose barb, the threads on Forespar 850 inline ball valve is NPSM (not tapered). This would require a 1/2" nipple adapter to the saildrive with NPT threads and NPSM threads on the valve side. The hose side would have a Forespar Elbow 1/2" Male Threads to 1/2" Barb.

I couldn't find a Marelon male to male adapter with NPT to NPSM threads but a 316SS version that should work, with the saildrive thread end properly mated with thread isolation compound.

There are other combinations that could be paired, depending on what you find out the saildrive threads are and the size of the discharge hose to the strainer. Post what you find and we can sort this out.

[TSweather]

Hi Bill,
Glad to see I'm not alone in looking for a better solution as the distain for the Yanmar part is easy to find in online searches, though solutions are few if any. I do like the idea of replacing it with a Marelon fitting and appreciate the links. I'll hopefully get down to the boat to remove the old one to measure by this weekend.

So far I have been leaning towards the part with the same function that is used on a bunch of different Volvo saildrive units. Volvo Penta Boat 1/2 Inch FNPT Plated Brass Ball Valve part #1140097 though who knows if it will last longer.




In the Volvo application it is technically 4 parts in total with little to no documentation available on materials and thread sizes, so I may need to source one to measure and figure out if it can be adapted. Below are the other Volvo specific part numbers.
#33 is 3583431
#34 is 947626
#36 is 3583432

[Vento Solare]

Todd - even though the Volvo valve is plated brass, I think a DZR Bronze valve would be better suited for seawater. Something like the Groco IBV-500.

[TSweather]

Well, I got the fitting out of the Saildrive and it is definitely a tapered thread. It's difficult to confirm the exact standard used in the threads, but consensus seems to be BSPT. I may take it to a friend who owns a machine shop to verify that it's not NPT.

Below are digital caliper measurements

~ Outermost threads where it goes into the Saildrive .804" / 20.44mm
~ Innermost threads near valve body .828" / 21.04mm
~ length of threaded area 12.5mm (part was installed with 10.5mm buried in the Saildrive)

~ id of fittings is 1/2"
~ od of water outlet barb to the strainer is .712" / 18.10mm

Since the fitting extends straight out of the Saildrive housing (unlike the new SD 60 style, which is angled up) it has a height limit of around 45.5 to 50 mm to clear the upper Saildrive gland seal while screwing the valve in. This mostly rules out the Hansen Products and Trudesign valves as they are much thicker than their metallic counterparts. That Forespar one you posted looks like it has a width of 43.9mm, which should fit, though Forespar only offers NPT and BSP thread choices.

As for materials, the internet is awash in differing opinions. While Marelon is likely ideal from a corrosion standpoint, it seems that if some metal is used, that a good sealant can at least partially isolate the connection of dissimilar metals using Sika 291, 3m 4200, or equivalent. I'm sure there are some schools of thought that a metal fitting is more fire resistant since it's in the engine compartment, though I guess in the event of a fire the thru hull technically isn't your biggest concern.