Re: Yanmar 4JH3-HTE Fresh Water Pump Replacement

Craig Briggs

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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