# Yanmar Kingston cock / seacock



## arf145 (Jul 25, 2007)

When the Yanmar manual refers to the Kingston cock when talking about the cooling system, I assume they are talking about the seawater seacock. Is this true? Is a Kingston cock different? 

I ask because my seawater seacock operates differently than my others--the handle has greater range of motion, which has made me a little unsure of whether having the handle parallel with the valve is full open or not. Instead of the usual 90 degrees of operation, it goes from a little beyond perpendicular to past parallel -- call it 130 degrees or so. 

Can someone set me straight on this?

Thanks.

Tom


----------



## Rockter (Sep 11, 2006)

Arf...

Take the hose off it and move the valve to the angles you want to check. It will be apparent very quickly if you have enough flow.


----------



## arf145 (Jul 25, 2007)

Excellent idea Rockter. And I'll be able to do that with a little less drama after I put the boat up on the hard this weekend ;-)

Thanks!

Tom


----------



## Tartan34C (Nov 21, 2006)

The Kingston cock is on the engine and it is used to drain the block.
All the best,
Robert Gainer

It has been a while since I looked at the book but that's the way I remember it.


----------



## JohnRPollard (Mar 26, 2007)

I don't know whether the terminolgy is being used correctly, but on both the Yanmars (2GM20F and 3GM30F) we've owned, the manuals have referred to the intake thru-hull seacock as the "Kingston cock". There is some funny terminology throughout the manuals due to the translation.

Usually the lever arm of the seacock should have a 90 degree throw. But I have seen some that go through 180 degrees, such that they can be closed down in either direction but are only full open when parallel to the flow. If you can go past 90 degrees you might be closing the ball valve down some. Definitely inspect it to see how it works.


----------



## arf145 (Jul 25, 2007)

Ah, so there are other ones out there like mine. I'm glad it sounds like it's been set open when parallel--I've been running the engine with it that way. I'll inspect in a week or so and report back just for the record.

Thanks for the info!

Tom


----------



## brak (Jan 5, 2007)

Kingston used to be a manufacturer of seacock type ball valves back in the day. Their name is used as a general name for seacocks in some languages (notably, Russian, for example) and my guess is - Yanmar picked the name up in translation.

In general, there is nothing special about the engine intake seacock - it opens and closes, just like any other on a boat.


----------



## Tartan34C (Nov 21, 2006)

brak said:


> Kingston used to be a manufacturer of seacock type ball valves back in the day. Their name is used as a general name for seacocks in some languages (notably, Russian, for example) and my guess is - Yanmar picked the name up in translation.
> 
> In general, there is nothing special about the engine intake seacock - it opens and closes, just like any other on a boat.


It seems that everyday there is something new I can learn. Thanks Brak.
All the best,
Robert Gainer


----------



## wfraser (Jul 4, 2005)

I have a Kingston Seacock as well and would to know if I want to close the seacock, do I need to loosen the nut opposing the handle? My boat is in the water and I'm a little nervous tampering with it without knowing how it works.


----------



## sailingdog (Mar 19, 2006)

Wfraser-

Shouldn't need to loosen the nut to operate the seacock in normal operation.


----------



## SailingTokyo (Feb 2, 2016)

*Re: Yanmar Kingston **** / seacock*

The ball valve referred to in the Yanmar manual as a Kingston seacock needs replacing on my boat. It appears to be a 3/8" BSPP (British standard pipe parallel) thread on the inlet side, 1/2" hose barb on the outlet side. It's fused as a single unit and appears to be made of bronze, which matches with the bronze funnel shaped through hull strainer. The Yanmar manual shows the same valve used for both Yanmar 2GM and 3GM engines.

Here's a pic of the valve in the Yanmar manual:









And a bit more info about this particular installation on my website here: Replacing Throughhulls ? Sparkman & Stephens 30' Restoration

I can't find a manufacturer anywhere that makes this part. From what I can find, all manufactures of marine use ball valves (seacocks) with straight thread only make them as small as 3/4". Does anyone know of a source for bronze or compatible material (non-brass) 3/8" ball valves? What do other Yanmar owners use?


----------



## JimsCAL (May 23, 2007)

*Re: Yanmar Kingston **** / seacock*

Nice revival of an ancient thread!

You may have to replace the entire seacock. You are correct that most ball valves are tapered (NPT) threads, not straight (NPS). The usual fix is to use an adapter. Note that in addition to bronze you can use Marelon valves.


----------



## SailingTokyo (Feb 2, 2016)

*Re: Yanmar Kingston **** / seacock*

JimsCAL,

Well yes, that's right. As I said above, the seacock (ball valve) needs replacing.

Question is, where can I find one? Does anyone know of a manufacturer that makes a 3/8 bronze seacock, or as Jim said, an adapter that would work to go from a BSPP 3/8 thread to a bronze ball valve?


----------



## JimsCAL (May 23, 2007)

*Re: Yanmar Kingston **** / seacock*

Don't get hungup on the 3/8" size. I don't think you will find any seacocks today under 1/2 inch. The important thing is the hose size and you can install the needed size hose barb in a 1/2 inch or 3/4 inch sea ****. As I noted, you may need to change the entire sea **** including the mushroom head. Groco or Forespar or several others make what you need.

Don'f forget that a nominal 3/8" or 1/2" or 3/4" pipe size is "nominal" and you have to check the measured dimensions against a table of the NPT sizes. Just Google it. For example, a 3/8 NPT thread is actually 0.675 OD.


----------



## overbored (Oct 8, 2010)

*Re: Yanmar Kingston **** / seacock*

not hard to find and cheeper then replacing the whole thing Groco 3/8" Bronze Full Flow In-Line Ball Valve GRO IBV375BSPP


----------



## SailingTokyo (Feb 2, 2016)

*Re: Yanmar Kingston **** / seacock*

overbored,

That's it! Thank you for confirming that such a part is still made. That gives me the part number to search for. Now to find a 3/8 to 1/2 inch bronze pipe barb, and a shop that will ship both to Japan...


----------



## overbored (Oct 8, 2010)

*Re: Yanmar Kingston **** / seacock*

I know that Vetus has down to 1/2" bspp. Conex bronze makes down to 1/4"mpt but no adapter mixed sizes. it is Conex banninger in England and they make the bspp stuff. it may be easier to get material and have one machined. could possibly machine one out of a 3/8" pipe nipple


----------



## JimsCAL (May 23, 2007)

*Re: Yanmar Kingston **** / seacock*

Note that Groco valve is NPT threads, not straight. You still need an adapter and not sure if there is any for that size readily available.


----------



## SailingTokyo (Feb 2, 2016)

*Re: Yanmar Kingston **** / seacock*

JimsCAL,

Actually, I believe that's incorrect. Note that throughout this discussion overbored and I have been referring to the British system (also used here in Japan), whereas you've been referring to the US system. The Groco ball valve which overbored helped find is BSPP (British pipe system parallel, parallel as in straight threads). The US equivalent would be NPS (national pipe straight), however it's important to note that BSPP and NPS although both straight threads are not compatible, as they use 55 and 60 degree thread angles respectively and have differing thread counts.

The 3/8" bronze ball valve made by Groco is part #IBV-375. I believe the one sold in the US carries only that number and may be NPT (tapered), whereas the one overbored found is #IBV-375 BSPP i.e. the straight thread needed to match my 3/8" BSPP through hull.

I make this distinction in order to leave this thread behind as a reference for future boat owners facing the same problem, and to highlight the need for checking thread matches carefully due to the different systems in use. And also to illustrate the difficulty in finding parts in Japan, which is the issue I face now as I try to find a shop that will ship #IBV-375 BSPP here...


----------

