Yanmar 4JH80 Spares

Feb 3, 2009
293
Knysna 550 SE Knysna, South Africa
I'm putting together a spares kit for my Yanmar 4JH80 engines on my Knysna 550 catamaran. This is above and beyond the normal consumables.

What I have so far is:
  • Raw water pump & gasket
  • Thermostats & gaskets
  • 1 set of injectors
  • Heat exchanger/lub oil o-rings
  • Radiator cap
  • Do I need Fuel Injector lines? I seem to remember seeing a sticker on the engine stating that they should be replaced with the injectors.
I'm not worried about an alternator as I can charge from other engine & have separate 24V charging system for the starting batteries.

I have a PDF of the service manual for the 4JHE/TE. Does that cover the 4JH80?

Similarly, I have the Parts Manual for the 4JH. Does that cover the 80 version?

Any suggestions would be appreciated.
 

dLj

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Mar 23, 2017
5,131
Belliure 41 Back in the Chesapeake
Where are you sailing and for how long?

dj
 
Apr 22, 2025
7
Hunter 1987 Hunter 37.5 Richmond Yacht Club
A backup starter motor. I realize you said you have alternate charging opportunities, but I just finished the Pacific cup on a boat with that motor and our starter went out. While we had some solar charging, it wasn’t enough to keep the batteries full on cloudy days. Unknown to me the backup starter we had was left home to save space and weight. They are relatively cheap and relatively easy to change. Just make sure you have a long 3/8” extension for your ratchet set because that is require.
 
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colemj

.
Jul 13, 2004
1,116
Dolphin Catamaran Dolphin 460 Mystic, CT
I think that engine is common rail. If so, then I'd want a spare ECU on board. Or two. Particularly since many cruising grounds are lightning areas.

We don't carry a spare raw water pump, but do carry rebuild kits for them. The rebuild kits contain every part except the cast housing and shaft, so the need for a complete pump would be extremely rare. On a catamaran, one has the luxury of using the other engine during the 1/2hr or so it takes to rebuild the pump rather than immediately replace it.

While you might not be concerned about losing the alternator as far as charging goes, you should have a way to remove the alternator from the engine and still use the engine. Otherwise, if the alternator bearings seize, you won't be able to use the engine. This could be an alternate belt that allows you to bypass the alternator, an idle pulley to take up belt slack from the removal of the alternator, or a cheap alternator that will only be used as a belt tensioner - it doesn't even have to work.

Mark
 
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