Checking the impeller duct bearings every 12 months or 100 hrs

[MrMoose]

I have a few questions regarding the "whichever comes first" 100 hrs/12 month check on the impeller duct bearings. I get the sense that based on comments to new-comers who are considering a Yamaha jet boat, most people on this forum only do plugs, oil, oil filter, intermediate bearing, some grease points, and maybe a look at the air filter every year.
As part of my 100 hr maintenance, I'm going to check the impeller duct bearings for water ingress. There are a couple of things in my shop manual that seem to be overkill and I'm looking for some opinions. First, is that the shop manual says to add loctite 518 (liquid gasket) between the Impeller duct assembly and the nozzle. I'm not sure that this is really necessary:


Second, is that my shop manual says to replace the o-ring with a new one before re-installing the cone (cap):


Third, once the cone is removed, assuming there's no water present, do you clean it out and pack it with fresh EPNOC grease? How much grease should be in the cone?

Lastly, in my experience, an outboard is much more convenient and cheaper to maintain than my Yamaha if I have to do this every year.

Thanks for your input.

 

[Matt Phillips]

Is this a required maintenance item on your boat or "something you want to add to your maintenance regime?" I checked the manual for my boat and there's nothing even written on this topic...

I would also think that an outboard is likely a bit cheaper to maintain than your boat and the reason being that with your outboard you're typically only servicing one engine vs. two. Off the top of my head, I'd say that on average I spend about two hours on spark plug/oil changes per year and once I purchased the oil extractor, it only costs about $130 for oil, two filters and eight iridium spark plugs.

 

[swatski]

@MrMoose Great write-up/topic!
I think the manual is full of goofy tips on lubricant/sealants. One issue for me was finding the OEM pump/cone grease, but I did find it!
https://jetboaters.net/threads/luck...on-cone-install-2016-ar240.12099/#post-208239

FWIW -- regarding the o-ring -- I re-used mine when I swapped to the L13 cones recently. Same with the old boat when I swapped to L13. The L13s use the same o-ring and the instructions simply say to reuse the OEM.
If I saw any evidence of water intrusion I would install new, but if all looks good I wouldn't worry and reuse. Mine were looking like new. These are simple o-rings, not gaskets, so sit in the groove and don't get squashed much.

--

 

[MrMoose]

Is this a required maintenance item on your boat or "something you want to add to your maintenance regime?" I checked the manual for my boat and there's nothing even written on this topic...

I would also think that an outboard is likely a bit cheaper to maintain than your boat and the reason being that with your outboard you're typically only servicing one engine vs. two. Off the top of my head, I'd say that on average I spend about two hours on spark plug/oil changes per year and once I purchased the oil extractor, it only costs about $130 for oil, two filters and eight iridium spark plugs.

Hi @Matt Phillips, I'm referring to the Yamaha service manual for the 2015 24 foot models:


The information in the Service manual does not conflict with what is in the owner's manual, it just goes into more detail. The maintenance charts between the two documents are identical.
In this specific case, my owner's manual says to "Check and lubricate" the Impeller ducts every 100 hrs or 12 months (which ever comes first), BUT it doesn't go into any detail about what this involves. The Service Manual, on the other hand, does specify what specifically needs to be done: