Cooling Water Fitting Sealant?

I've read many post on this but technology is changing. So what is the newest and best sealant to use on all the cooling water connections? Thanks

 

....newest and best are not automatically coexisting..... Which components, what materials are to be sealed against which temperatures and pressures?

 

Thank you for your reply! Understood. Aluminum exhaust manifolds to SS fittings in and out with some brass and aluminum hose barb fittings to hose. Cast bronze water pickup to SS street elbow to brass valve to SS barb to hose to SS barb to plastic sea strainer to SS barb to hose to cast bronze pump. Using a half closed system from Hardin with antifreeze. Aluminum water pump on engine to hose to copper heat ex-changer to hose back to chromed steel tube on aluminum water pump. Last is a trans and engine oil cooler to hose and the oil hoses. Plan to use the recommended pressure hose fitting for Velvet Drive and engine oil circuit. I have no idea yet about temps or pressures. I have researched many articles on electrolysis and am trying to do what is best when and where I can. Thank You!

 

Baeckmo is in Sweden; give him time to respond. It is night there. He is the water expert.

 

Seems like you have a sampler of incompatible metals. What do you mean by a "half closed system". Usually there are open systems that use sea (lake) water, and closed systems with a heat exchanger.

 

Thank you for the question! Well the heat ex changers (two) and the exhaust manifolds will see the sea water. The engine block will only be circulating antifreeze with one of the ex changers. This system was described to me by Hardin Marine as a half system.

 

Frankly, I don't see any use for sealants at all, save for the few flange fittings. But, as Gonzo has pointed out you have a mishmash of metals that have to be galvanically isolated from one another, and that is more challenging that getting it sealed. A major reminder here, is: Do not use natural rubber in the hoses, it contains graphite, and will directly cause corrosion of the salty side metals!

 

Thank You for your comments! I'm thinking this boat will mainly only see fresh water. All the hoses so far are silicone based. My question was about sealing the pipe tapered threads. Teflon tape or some new paste type sealant? Thanks! Bob

 

My favourite go to for sealing threads, gaskets, hose barbs, lip seal housing OD surfaces, & o-rings in some situations is the ages old Permatex Aviation. For skin fittings through the hull I prefer a polyurethane sealant like Sikaflex.

 

I prefer to use the Permatex for threads than PTFE tape Bob. PTFE does not seal, but it lubricates the thread so that it will tighten more until the brass snaps like a carrot.

I always used Permatex on flexible exhaust joints, which are often high graphite rubber on cast aluminium and corrode badly.

That's kind of it for me, Permatex Aviation and Sikaflex. High temp silicone can be very useful on exhaust gaskets, but watch it, it will age you 20 years over night if it gets into the fuel system.

Things don't change that quickly in marine because the nature of the operating environment demands materials and techniques that give reliable and repeatable results, it demands excellence in every aspect, and you still mightn't make it home one time after doing everything possible, but you give yourself a vastly better chance.

 

Thank You! Your comments are exactly what I wanted to hear. I will follow your advice. At 78, I'll be very careful with the fuel line system. I'm planing to use Holly brand filters and pump for the high pressure fuel injection system. Thank You!!! Bob

 

You are welcome, any time. I'm a youthful 64 yo whipper snapper. Silicone in petrol swells from a grain of rice to a pea, then blocks wherever it lodges, and many amateur repairers aren't aware.

 

Is this a marine fuel injection system? Otherwise, that will be a huge problem.

 

Good Morning! The sealant request is only for the sea water plumbing. I am planing on a fuel injected 6.2 LS engine with the fuel system purchased from Holley. None of the fuel injection system or hardware has been purchased yet. Your thoughts and ideas would be greatly appreciated? Thank You! Bob

 

Is this a marine fuel injection system? Otherwise it may have the pump in the tank which won't work for a boat. This setup looks like a frankenengine. For example, aluminum exhaust manifolds should be cooled within the closed system. You can save a lot of money and headaches buying a marinized engine. What is the goal on mixing a matching parts?