871 T.I. Engine Zinc

[wndsr]

I want to replace the zincs in the cooling system of my boat. I dont remember if they are 2",3 3/8" or 3 5/8" in lenght. I do know they are 3/4 dia and 1" plug dia. Does anyone know for sure?? I have Detroit 871 T.I.'s
Thanks

 

[REBrueckner]

I do not know spec lengths, but I do know zinc pieces are always ending up in intercoolers and heat exchangers. So I use short ones, 2 inches, to minimize extension into the water flow. Originals were longer.

I'm also going to permanently eliminate the one zinc just before the heat exchanger. Whenever I check the one before and the the one after the HE, no water runs out..so they seem to sit in air 99% of the time. Hence one on the output side, where it can't clog the HE should be just fine during run and subsequent drain time.

What's also interesting is the the intercoolers, a VERY expensive component, do not have zinc protection! I assume raw water drains out of these as well as they sit high in the raw water system.

 

[Traveler 45C]

Go here: http://www.boatzincs.com/engine.html

Click on one of the "More Info" links and you'll find a list containing info for your eng.

Hope this helps!

 

[wndsr]

Eliminating the one before the heat exchanger makes sense. Does anyone else want to weigh in as to why we shouldnt do this????

 

[Will]

My engine zincs are pulled and inspected every three months. Wear is logged, they are scrapped, wire brushed and reinstalled or replaced if necessary. Although the ones sitting in air during engine shut down deteriorate more slowly than those immersed in water all of the time, they do deteriorate leading me to believe that they still serve a purpose. This practise has been in place for three years and to date, I've had no problems with zincs or zinc flakes appearing in heat exchangers or coolers.
Will

 

[REBrueckner]

I don't have the "Will" power to check zincs every three months, but that's a method that can't be beat!

The theoretical reason for having zincs at both ends of a HE is that zincs protect best when immediately adjacent to the metal being protected;hence,for example, a shaft zinc is always placed close to the prop it is protecting.

Zincs can't provide galvanic corrosion protection unless immersed in salt water which is an electrolyte. Any engine or zinc corrosion when zincs are exposed to air is a local chemical reaction, like rust, minor/irrelevant, and not related to galvanic corrosion.

There is a natural decay of zinc in a moist salty environment due to local chemical reactions as zinc is an active metal, but that reaction does not protect valuable engine metals. Most of zinc mass is lost to abrasion from rapid salt water movement not engine metal protection. A zinc will gradually deterioriate even if left on your deck...the dull color versus original bright cooler is the result of zinc oxides forming on the surface. .

In theory, larger engine pencil zincs might provide more protection against electrolytic (stray current) corrosion; but most such reactions will occur in shaft zincs, not tiny zincs in the interior of an engine.