Zinc Locations

[kwerges]

Quick question... Started doing my own zincs in my (new to me) 8V71TI's. I was told there is two in the heat exchanger, one in the raw water pump, and one in the trans-oil cooler. I easily located the two in the exchanger and one in the raw water pump, but the trans-oil cooler is built into the heat exchanger. I think my buddy was maybe thinking of a different Detroit series, as I cannot locate a zinc head in the transmission oil cooler. Anybody?

[rsmith]

Search the threads on engine zinks,another HOf bickering subject. I was told when we bought the boat 37 years ago to use only 1 zink in the HE because 2 created a "miliamp current" I use 1 in the RW pump but a lot of guys think its unnessasary. I dont have one in the trans cooler. BTW NO teflon tape! It acts like an insulator and can isolate the zink. I use a little swipe of permatex #2

[bobk]

Search the threads on engine zinks,another HOf bickering subject. I was told when we bought the boat 37 years ago to use only 1 zink in the HE because 2 created a "miliamp current" I use 1 in the RW pump but a lot of guys think its unnessasary. I dont have one in the trans cooler. BTW NO teflon tape! It acts like an insulator and can isolate the zink. I use a little swipe of permatex #2

Bob Smith of Lehman fame also advises not to use Teflon tape. I always do use one and a half turns of the Teflon tape and check for continuity with an ohm meter. Always have a good electrical connection.

Bobk

[saltshaker]

Search the threads on engine zinks,another HOf bickering subject. I was told when we bought the boat 37 years ago to use only 1 zink in the HE because 2 created a "miliamp current" I use 1 in the RW pump but a lot of guys think its unnessasary. I dont have one in the trans cooler. BTW NO teflon tape! It acts like an insulator and can isolate the zink. I use a little swipe of permatex #2

That's the first time I've heard that about 2 zincs in the HE. I've eliminated one on the intake side or the raw water pump because on my 8V71's and the 6V92's there was also one on the discharge side. This way if a chunk broke off, it wouldn't damage the impeller.

[bostonhatteras]

Also a first to hear about the milliampere phenomenon. Sounds plausible though. I want to congratulate R Smith for using a completely old school yet fully superior sealing compound named permatex 2! No rtv or other product even comes close to performing as well as permatex 2 especially in the applications we are using it for on the boats. If you follow tightening schedules, you will never get a leak and most gaskets will just peel off when you disassemble. I think it's funny to see all the people struggle with rtv silicone thinking it has to be better because it newer! Lets hear more about zincs creating the milliamp between them....now that you've opened that Pandora's box! Btw. My raw water pump zinc corrodes so slowly I rarely replace it, just wire wheel away any corrosion and stick it back in. Here's another debate subject: is neversieze an insulator or a conductor? And if anyone else knows about neversieze, does it actually have a 'mil thickness'? Meaning can it take the place of grease in an interference fit situation or would it actually make clearances smaller? Inquiring minds want to know.

[Nonchalant1]

He was thinking of a different model. Your oil cooler is in the bottom of the heat exchanger, which is covered by the HE zinc. I agree only need one there. You do need on on the water pump though.

[MikeP]

I know this will start yet another discussion re zincs but...our 53 MY has not had a RW pump zinc since at least 1992 per the maint logs, maybe even before that. It has not had two HE zincs since 2004 and sometimes has none - I go back and forth on whether to use one on the output side of the HE or not.

There is no evidence of any kind that indicates it has been a problem. However, I readily admit that one example, does not a scientific study make. OTOH, I do find it interesting that a more modern marine-type engine, like the engines used by Northern Lights for their gennys have no zincs anywhere as supplied by the factory and no recommendations to add or consider adding zincs in their instructions.

The zincs in our 8v71TI HE's are above the level of the water remaining in the HE when the engine's re shut down. Therefore, even if they had some theoretical benefit, they have no practical value because they are only in the water when the engines are running. The other 99% of the time, they are high and dry. Same is true of the RW zinc.

Again, no science whatsoever here - IMO, they provide nothing...as Northern Lights seems to agree.

But, like everything else, do what you are comfortable with. If you feel better having the RW zincs in the pump/HE, by all means install them.

[bobk]

[QUOTE=MikeP;227223]The zincs in our 8v71TI HE's are above the level of the water remaining in the HE when the engine's re shut down. Therefore, even if they had some theoretical benefit, they have no practical value because they are only in the water when the engines are running. The other 99% of the time, they are high and dry. Same is true of the RW zinc.

Again, no science whatsoever here - IMO, they provide nothing...as Northern Lights seems to agree.

QUOTE]

Mike, if the zincs are indeed above the raw water level, I'd put them in and expect they would last forever. On the 6V92 TA's the HE zincs are underwater. They are well degraded after a year, so I try to change them at 6 month intervals as the boat is in use year round. On the Weterbeke the same is true, underwater, but these only last 3 months. But for a $1.29, I'm happy to R&R them. In both cases they are doing something.

Bobk

[kelpy]

Don't put a zinc pencil on the intake side of the raw water pump. Very bad things will happen when it erodes and breaks off as they sometimes tend to do.

[kwerges]

As previously mentioned as a concern, I too only install the HE zinc on the exit from the HE. I also installed one in the water pump. Its probably only peace of mind, but it helps me sleep at night. Thanks for the opinions and the facts...