Right after we bought our boat, I asked the dealer about this. I asked why Yamaha didn't include the valves, and inquired what it would take to outfit our boat with them as an emergency precaution, especially given they are very inexpensive valves. He said he didn't know for sure why Yamaha doesn't include them and speculated that they were possibly worried someone would turn them off by mistake and destroy the engine. He also wisely advised me to drop the idea of having them installed as that mod would likely void our warranty immediately.
I took his advice, and carry hose shutoff clamps instead like the others suggested.
I have never, not once, even for a second, stopped to consider this. Even if it wasn't the cause of an issue, having them on there seems like a perfect situation for Yamaha to have a legit point to deny a warranty claim, since you wouldn't be able to prove you did OR did NOT have them closed, and Yamaha could fall back on "this item could have contributed to this, and you can't show us one way or the other that it didn't, so...DENIED!"
I had my clamps before we ever picked up the boat because I didn't think I'd be getting to this too quickly, and you've made an awesome case for me to skip doing this! The manual even mentions clamping off the hose with a pliers or some sort of hose clamp, so I'd be following Yamaha's direction with my pliers. Seems like that's my best option, to keep doing what I've been doing. Laziness pays off! Thanks!
With those pinch off pliers you guys are showing....is it ok that they don’t pinch off the hose completely? the clamp doesn’t look parallel .... is the pinch enough to prevent back flow during towing or limping?
As you tighten them down on the hose, the lack of parallel won't be an issue, the "closed" end in those pics will be closer to parallel when they're put into actual use. I've used those for different lines on vehicles I've worked on, and they worked well enough to kink an old hose I was using them on - it should have been replaced anyway, and they don't have to be closed enough to stop all water, just slow the flow enough to make the highly unlikely even of backflow to the engine an even smaller possibliity.
If you're worried about it, there's more options out there.
Here's a link to my Gear Wrench shutoff pliers that I use. The jaws swivel, so no matter what angle you're at, they'll at least be parallel to each other, and they can easily be used one-handed. The arc piece is a toothed part that essentially ratchets and holds position as you close it, so if you need to regrip it, it'll stay in place and you won't require that second hand and liberal swearing (more than you'll already be doing).
If you follow your garden hose wash connector down into the engine bay (usually it's a red hose) it will come to a " Y " fitting,
clamp after the Y if you just want to prevent water flow while towing,
if you want to clamp to help with pressure during garden hose fresh water flushing clamp on the hose from coming from the jet nozzle before the Y fitting
Sonofab.... I winterized my boat twice already, and it never dawned on me to do this (or I didn't remember it)! I bookmarked your post so I can forget to look at it next winter ?
?
?