Re: Yanmar 4JH3-HTE Fresh Water Pump Replacement

Dan Carlson

Hi Craig,. Thanks for the recco on the fluid.  Yes, unfortunately coolant is another of those mystery fluids where you are either in a well stocked parts store and faced with a myriad of mind boggling choices, or you are in a remote location with the choice of one mystery fluids written in another language.

I've always gone for fluid that is good for diesel engines and compatible with aluminum.

I will change out the fluid again as soon as I can.

And, yes I will also try to rebuild the pump to have a spare. I'm sure that it is both the seal as well as the bearing. 

Thanks again for the response with the helpful information and suggestions.

Regards Daniel and Lori Carlson on sv BeBe, SM #387.

On Wed, Mar 18, 2020, 12:26 AM Craig & Katherine Briggs SN 68 Sangaris Tropic Isle Harbor, FL via Groups.Io <> wrote:

[Edited Message Follows]

Hi Dan,
Others have commented that you should be fine with what you've got plus, perhaps, some sheet gasket material. Under your #3 though - tricks, traps or learnings - I'd add to be sure to replace your antifreeze (coolant) with one specifically rated for diesel engines, not the much more commonly available products sold for car (gasoline/petrol) engines. That's a tip I picked up from a fantastically knowledgeable diesel mechanic (engineer for the Brits) in Annapolis who gave a super presentation at the SSCA Annapolis Gam a couple of years ago. It was new knowledge to me at the time as I didn't know there was a difference - there is.
Cheers, Craig
PS. You mention the leak is the shaft seal and you're replacing the whole pump. Next step I'd suggest is to rebuild the old pump with an inexpensive shaft seal so you'll have a fresh pump good to go when your new pump starts leaking in the future. An easy DIY job.

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