In December.....

[KevJul2019]

This year I only fogged my engine for 5-10 minutes Thur the air box while on the hose. My question is: will I be ok if I didn’t pull the spark plugs and spray fogging oil?? Should I go do that now after boat has been sitting for a couple months now. I did run 4 gallons of anti-freeze after I fogged thru air box.

 

[ripler]

I had my Yamaha for 10 years and never fogged through the spark plugs, I always sprayed fogging oil through the throttle body. I would pull the air inlet hose off of the throttle body and spray fogging oil directly into the throttle body until the engine died, then I pulled the lanyard and cranked the engine for a few seconds while spraying so the oil didn't burn off. I never fogged while on the hose since I didn't want to introduce more water into the system.

When you said that you ran anti-freeze after you fogged, that means you should have been running the engines and if that's the case you burnt off the fogging oil. So you have 2 options, do as I described above without running on the hose or pull the plugs and fog directly into the cylinder.

 

[haknslash]

Spark plugs are an annual replacement or should be so I’d just swap them in the spring when you prep the boat. These engines don’t like anything but as near perfect spark plugs.

 

[Ronnie]

When I fog my engines I do so through the throttle body instead of through the spark plugs holes. It’s just easier and it eliminates the potential breaking a plug off in the head or cross threading it.

Yamaha jet boat engines are self draining, Is using anti freeze really necessary in a Yamaha powered jet boat? I thought anti freeze is only required in engines with a closed loop cooling system.

 

[haknslash]

Him fogging through the air box is essentially the same as through the throttle body since the air is is just before the TB. He didn’t fog through the spark plug holes as that would be impossible with the engine not running lol.

in regards to water in the engine, I don’t think you could get all water out of the ports and water box but it seems the engines don’t retain enough to crack. Putting antifreeze in them would just be safe if you do have hard winters. I put antifreeeze in mine even though we typically don’t have long hard winters. We are in the 20’s this morning though brrrrr!

 

[Ronnie]

I recall doing what the guy in the linked video did. That is, Spraying fogging oil into the throttle body (bodies) until the engine died and following up by spraying fogging oil into the cylinders through the spark plug openings with the engine off, then cranking the engines with the lanyard out to coat the cylinder walls without burning off the oil. I eventually only fogged through the throttle body (bodies) and now I don’t do either anymore and just run stabil at the end of the season instead.

I understand why antifreeze is involved with closed loop cooling systems but not with self draining engines like Yamahas have. There is a reason Yamaha jet boat engines don’t have freeze plugs, the water boxes don’t have much standing water in them and I never saw any instructions in the manual involving antifreeze. Not really a concern for me since it rarely gets very cold in the SF Bay Area but I’m just curious about the practice.

 

[haknslash]

Close loop doesn’t matter since that utilizes coolant already. I have closed loop for portions of my engine and raw water as well. What matters is if there is raw water in areas where expansion would be an issue then anti freeze would be a good idea for the winter if you live where there are harsh winters or just want to be safe knowing it won’t break anything if it were to freeze.

In regards to Yamaha no idea how they ensure all passages in the block and cylinder walls to expel water. Maybe just lucky lol but I don’t know lol. I agree the water boxes do not typically hold that much water but was more so saying that you’ll never truly get a Yamaha “dry” or free of water. If someone were concerned then there is no harm in using coolant to keep things safe.

 

[AmesJainchill]

Only thing I put antifreeze through/in is the transom shower tank and pump, and the lower holding tank of the head. Also ran salt terminator through both motors just to minimize or eliminate any scale or mineral deposits that may have formed from the lake water. Perhaps unnecessary, but an OCD thing for me anyway. Then the dealer takes over for indoor storage, winterization and 50/100 hr service (so far put appx 46 and 53 hours my first two seasons with the boat). Related to winterization, I asked about antifreeze at the end of my first season and they specifically said they don't use it (not that there is any harm in doing so). I believe they fog through the TB, was told they blow compressed air through the flush ports and ensure exhaust box is clear of water. They replace plugs in the spring prep.

 

[haknslash]

FWIW I never used anti freeze in my Yamaha or previous PWC’s. We don’t get harsh winters here but there were times we had days of snow and freezing temps. Never had an issue. If in doubt it’s safe to use though.