Only the threads on the cap hold the zinc in my M4-30 heat exchanger and the zinc pencil is treaded into the bronze cap so the cap is reusable. Despite that the engine is fresh water cooled and charged with a 50/50 water antifreeze mix I change the zinc pencil about every 2 years and I use teflon tape on the cap treads that meet up with the heat exchanger...the zincs are only partially eaten away after 2 years and could probably go longer but why try for longer, they are inexpensive to replace. I find it better to shorten the zinc pencils to about 1 inch or so showing above the treads, that makes installation from underneathe easier for me.
Dwight Veinot C&C 35 MKII, *Alianna* Head of St. Margaret's Bay, NS d.ve...@bellaliant.net On Thu, Apr 2, 2015 at 9:08 AM, David Knecht via CnC-List < cnc-list@cnc-list.com> wrote: > Last weekend I managed to take the heat exchanger off my Universal M4-30 > in order to figure out why it was leaking antifreeze. The trick that > seemed to get the bolt I was having trouble with unstuck was heat from a > grill lighter. Now that I have it home, I am going to replace the seals > and O rings from the end caps. The zinc was completely gone, so doing that > as well. I took the cap off the zinc but an inner threaded part stayed in > place and nothing is sticking into the exchanger except the nub of zinc. > 1. Am I right in presuming that nothing is holding it in there except > gunk and corrosion and I can bang it out from the outside? This may be > more obvious when I have the new part. > 2. When I replace it, should I put something like Tefgel/Marelube on the > threads or Loctite? > 3. The larger problem is that several of the ports for tubing connections > are seriously out of round as if they were mashed at some point (I don’t > see how could have done it so I am blaming the proverbial PO). Should I > worry about this and presume the clamp and flexibility of the tubing will > seal (it seemed the end cap that was leaking, not the tubing ports) or is > there some way to round the soft brass of the ports? > > Thanks as always- Dave > . > Aries > 1990 C&C 34+ > New London, CT > > > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the > bottom of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com > > >
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