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bestfriend 03-23-2007 05:16 PM

Raw water pump
 
Yet another question. I am replacing the raw water pump. On land I would use teflon thread tape on the 90 Degree elbow threads to make a good seal. Is it the same practice for raw water, or will it eat away the tape? I was also told that some use polyurethane caulk to make the seal, is that correct?

sailingdog 03-23-2007 05:18 PM

Teflon tape please... not polyurethane caulk... Teflon is far more chemical resistant IIRC...

Cruisingdad 03-23-2007 05:20 PM

Agree with SD, on this topic and this topic alone. This should not be considered a total agreement or confused with any agreement in the past, present, or future.

bestfriend 03-23-2007 05:20 PM

Oh, forgot to ask, how about on the zinc threads on the heat exchanger?

sailingdog 03-23-2007 05:31 PM

Yes, unless you like tiny, hard to trace, leaks...

BTW, do not take any agreement between CD and me to be an indicator of future agreement...

bestfriend 03-23-2007 05:33 PM

Thanks guys, question answered, thread solved!

svwhirlwind 03-25-2007 02:11 AM

I would reconsider teflon/caulking the threads on the HE zinc, the more you insulate the zinc from the HE the less effective it becomes. It is conceivable that the effects of the zinc could be completely negated, therefore I would recomend no teflon tape/caulking . This is one time a minor leakmaybe acceptable.

sailingdog 03-25-2007 07:50 AM

Svwhirlwind's got a very good point... nix the teflon tape on the zinc... he's completely right... it would act as a galvanic isolator...which is the last thing you want on a zinc. D'oh... my bad. While I don' t like tiny leaks, corroding heat exchangers are far worse...cause then you get a lot of them, plus a costly repair... ;)

Faster 03-25-2007 11:08 AM

Yes, you don't want to isolate the zincs....

Technically the teflon is really there to act as a lubricant/friction reducer and the tapered threads should seal themselves by design - but the tape will of course make up for some flaws or lack of tightening and is routinely used to reduce the possiblity of leaks.

An alternative to tape, especially if you are dealing with a system where you don't want an errant piece of the tape to enter the system is a teflon-based paste-type sealant.

bestfriend 03-25-2007 12:27 PM

I think the HE zinc should be ok by itself. It has a 1/4 inch of fine thread and feels very tight without the tape. Thanks guys.


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