Heat Exchanger Zinc Plug question

[scenarioL113]

On my Cummins 4BT Heat Exchanger there is a 1/2" threaded plug on the bottom of the unit. It has a Zinc in it and I was wondering if I could use that port as a water source fro my PSS Dripless shafts.

I know the port is raw water and will work for a raw water supply to the PSS system but removing the zinc will pose new potential electrolysis threat.

Is there any way I can protect the heat exchanger (zinc-wise) and use that port for the PSS.

I am trying to avoid installing another thru hull.

[bob lico]

leave that zinc alone essential to heat exchanger.. take water for pss from gear cooler has 1/4npt plug on bottom . from that to pss seal with clear reinforced hose.so you can see water flow.

[scenarioL113]

Bob Thanks!

I was just realizing that after I took another look at my gear cooler.

The plug is actually toward the top because of the way they are mounted. I removed the plug and red antifreeze came pouring out (boat is still winterized).

I am sure this will work, I think it 1/8" NPT not 1/4" but like I said water copiously came out so when the pump is turning there should be plenty of volume.

I am not planning on installing a shut-off since I can shut the raw water down at the sea-cocks.

[In Memory of Vicroy]

You can also tap raw water from the Sherwood raw water pump - there is a small pipe plug there too. The gear cooler plug is probably easier to get at and closer to the shaft log. That zinc is the only one in the H/E so as Bob says, leave it alone, and change it when it gets half eaten up or so....and use two wrenches to remove and install it so you don't crimp the soft copper body of the H/E.

UV

[scenarioL113]

I did not know that about the sherwood pump, I will keep it in mind and like you said, the cooler is closer to the shaft.

Using 2 wrenches on the heat exchanger zinc is sound advice.


Thank you, as usual my initial ideas are somewhat off, I am going the gear cooler route. I confirmed my cooler has 1/8"npt, I will compare the ID to a 1/4npt fitting, I think they are pretty close and I am sure it will be enough water. I am doing one PSS per engine per side, its not going to be TEE'd off anywhere either.


My head is spinning, I have more individual projects going on right now with this repower and conversion than I know what to do with.


short list just in last 2 months or so:

remove rear deck
installing PSS seals
remove and install cutlass bearings
install new shafts
install new fuel lines and fittings
plumbing new racor 500's
plumbing 12v priming pump for fuel system
install new fuel tank
plumbing exhaust
rebuilding 1 turbo
replacing all grounds (rudders, struts, shafts etc...)
raise hatch covers for higher engines and fabricate mounts 4 hinges
make custom brackets for trans coolers
make custom brackets for 1 coolant overflow tank and install
paint both engines to look fresh


Still need to:

paint bottom
wash and wax vessel
wire a new twinscan tachometer
finalize the hoses from sea-cocks to intakes of engines
make up new wiring harness (just on engines to mate to existing harness)
buy new batteries (not looking forward to that $$$)

my hands hurt, my head hurts, and I cant think straight.
my garage is a mess, my tools are a mess

Is it possible that I may ever get it ready to go fishing???

[In Memory Walter K]

Somewhere in the middle of the season while filleting some Bass or Fluke and having a cold beer, you'll wonder how you ever did it all. But you will...and you did! Stick to it...we're all rooting for you! Walter

[bob lico]

and one added bonus in the fall when you winterized look for the tell tale red antifreeze flowing thru the hose . that it ----that engine is winterize because thats the last stop before exiting boat unless your lucky enough to has a person watching the exhaust pipe at the trasom normally not the case.