Rubber safe grease for seacock valve with rubber inserts

[Ruso]

Gentlemen,
I have original seacocks/vales on my Tayana 37 1981.
About one year ago and some of them started dripping little water.
I think I made mistake trying to address the issue with injecting some grease into them. After year two valves (head and galley sink) really hard to turn.
I didn't know they have a rubber inserts (#4 on image) ( into them and I suspect petroleum based grease caused the rubber to swell.
Of course it is the time to replace them. As an option I plan to disassemble them clean, sand the swelled rubber, leap the valve with leaping compound and grease it.
Reading silicone and lithium grease are safe on rubber..
Any suggestion on silicone vs. lithium?

[thinwater]

Originally Posted by Ruso

Gentlemen,
I have original seacocks/vales on my Tayana 37 1981.
About one year ago and some of them started dripping little water.
I think I made mistake trying to address the issue with injecting some grease into them. After year two valves (head and galley sink) really hard to turn.
I didn't know they have a rubber inserts (#4 on image) ( into them and I suspect petroleum based grease caused the rubber to swell.
Of course it is the time to replace them. As an option I plan to disassemble them clean, sand the swelled rubber, leap the valve with leaping compound and grease it.
Reading silicone and lithium grease are safe on rubber..
Any suggestion on silicone vs. lithium?

• The o-rings are not rubber, they are one of several synthetic elastomers. Find out which one. But if they are 1981, new o-rings would make sense.
• Lithium grease is petroleum. The lithium soap is the thickener.
• Silicone could have advantages, but more important is getting the correct viscosity.

What was the original recommendation? Go with it.

[Ruso]

Thank you for input, Thinwater. Unfortunately I am not on the boat, but based on discussion with another sailors those inserts are not o-rings - see the picture.
Silicone, then a good choice I guess. Viscosity? Not sure if it is mater since temp range even for galley sink is limited.

Originally Posted by thinwater

• The o-rings are not rubber, they are one of several synthetic elastomers. Find out which one. But if they are 1981, new o-rings would make sense.
• Lithium grease is petroleum. The lithium soap is the thickener.
• Silicone could have advantages, but more important is getting the correct viscosity.

What was the original recommendation? Go with it.

[japawil]

Groco recommended silicone on the SV series.
Be sure to back off the t shaped wing nut before opening or closing in order to release the compression on the plug thus making movement much easier. While the wing nut is backed off it’s not uncommon that it will leak a little. Tightening the wing nut should stop the leak.

[Ruso]

Originally Posted by japawil

Groco recommended silicone on the SV series.
Be sure to back off the t shaped wing nut before opening or closing in order to release the compression on the plug thus making movement much easier. While the wing nut is backed off it’s not uncommon that it will leak a little. Tightening the wing nut should stop the leak.

Thank you, Japawil. This is actually strange but on some of mine seacocks tighten wing nut too much makes leak more. I found tighten just enough to stop leaking is optional.
Most of the leaks was coming from the seacock flange.

[leandroflaherty]

3M dialectic grease.

[Spot]

Groco markets a ball valve grease as part of their ULUBE line.
Prices vary quite a bit online.
While searching that, I ran across Dow Corning High Vacuum grease, which we used in the maintenance department at work and for rebuilding SCUBA gear at home. The guys gifted me a half-tube when they were cleaning up one of the shops.

Caveat: I don't have seacocks, just diving gear...

[thinwater]

Originally Posted by Ruso

Thank you for input, Thinwater. Unfortunately I am not on the boat, but based on discussion with another sailors those inserts are not o-rings - see the picture.
Silicone, then a good choice I guess. Viscosity? Not sure if it is mater since temp range even for galley sink is limited.

There is a HUGE range in grease stiffness. You need a product made for plug valves, not bearings.

[chasmains]

Go to McMaster-Carr and review their list of valve seal lubricants. There are many and varied. That said, I have used silicone o-ring grease for years in valves for the nuclear industry. It is totally waterproof and always slick. Perfect for water valves.

[Jetx]

Try Superlube synthetic (non petroleum). Lots of uses on the boat.

[BillKny]

One of the best greases for this is Dow Molykote 111. It is a moderately stiff silicone grease ideal for slowly moving parts. It won't flow off parts, and like most silicone greases it never dries out, is much more resistant to water wash-out than normal petroleum greases, and will not damage rubber or other elastomers.

It is also a long lasting lubricant ideal for manual toilet pumps.

[Ninedotsix]

Originally Posted by Spot

Groco markets a ball valve grease as part of their ULUBE line.
Prices vary quite a bit online.
While searching that, I ran across Dow Corning High Vacuum grease, which we used in the maintenance department at work and for rebuilding SCUBA gear at home. The guys gifted me a half-tube when they were cleaning up one of the shops.

Caveat: I don't have seacocks, just diving gear...

The product previously known as Dow 111, now marketed as Molykote 111 is the same as high vacuum grease.
Perfect consistency for application to the valves.
Groco has the ideal replacement for the rubber seacocks in their stainless steel ball valve seacocks, which are cost effective and easy to use; satisfying to the user.
~ 9.6

[jmschmidt]

There are no O-rings in the type of sea cock the poster mentions. And there are no replacements available for the bung type insert that I have been able to find for this model Groco sea cock. I even talked to an old had at Groco who told me they no longer make the model or parts for it and he said he did not know of any after-market source for them either.

I have babied mine for thirty years. With good and frequent maintence they will last a long time.