Weird rattling sound in cold weather

[FLJetBoater]

So towed the boat the other day about 2 hours. Temps when I left were quite cold (30-32F). When I put the boat in they were around 45-50. Very strange sound from one of the engines. Like marbles in the engine but no impact on performance or speed. Took it really slow to see how it would react and didn’t get much different at different RPMs.Got to initial destination and stopped for 5-10 mins with engines off then went back out and it was gone.

The sound hasn’t been back in 3 days and temps have been warmer (70+) I’m wondering if towing created a windchill that froze some water in the exhaust which rattled around but then eventually melted once the engines warmed up. Anyone experienced anything like that before?

 

[Elliott]

FWIW, wind chill cannot freeze water, but the flowing air will cause an object or liquid to achieve ambient temperature more quickly. Wind chill is a measure of how cold it feels to bare human skin, but it does not change what the actual temperature is. If it is 35 degrees and the wind chill is 25 degrees, water will never freeze. However if it is 32 degrees, a strong relative wind (like towing) will cause water to freeze in a short period of time versus maybe hours with no wind.

 

[FLJetBoater]

Thanks for the info I hadn’t realized it was really like that. I suppose it could still explain it but like everything else guess I’ll just keep an eye for it. Hasn’t done it again now in 5 days and all were warmer temps

I remember when we lived in Ontario my dads old regal I/O always used to act and sound funny when the weather got into single digits (celcius)

 

[FSH 210 Sport]

Thanks for the info I hadn’t realized it was really like that. I suppose it could still explain it but like everything else guess I’ll just keep an eye for it. Hasn’t done it again now in 5 days and all were warmer temps

I remember when we lived in Ontario my dads old regal I/O always used to act and sound funny when the weather got into single digits (celcius)

Did you blow the water out of the boxes the time before when you put it away? Ice cubes in there would have stopped as soon as the box got full of water?

 

[FLJetBoater]

Did you blow the water out of the boxes the time before when you put it away? Ice cubes in there would have stopped as soon as the box got full of water?

I don’t usually rev up to blow it out as I’ve heard mixed opinions on that. And we rarely ever get close to freezing temps here. I just let the engine run for 20-30s after I turn the flush hose off.

 

[FSH 210 Sport]

I don’t usually rev up to blow it out as I’ve heard mixed opinions on that. And we rarely ever get close to freezing temps here. I just let the engine run for 20-30s after I turn the flush hose off.

I see... what are the mixed opinions? Yamaha states three half throttle revs <4K rpm’s as part of the flush out procedure.

 

[FLJetBoater]

I see... what are the mixed opinions? Yamaha states three half throttle revs <4K rpm’s as part of the flush out procedure.

I’d have to go and search again but some people have posted that revving these engines up out of the water repeatedly isn’t a good idea.

What is the benefit of blowing the water out as part of the flush procedure if you’re not at risk of freezing?

 

[FSH 210 Sport]

I’d have to go and search again but some people have posted that revving these engines up out of the water repeatedly isn’t a good idea.

What is the benefit of blowing the water out as part of the flush procedure if you’re not at risk of freezing?

I’d say the risk is leaving a lot of standing water in there is more chances of corrosion ... if the water is removed from the boxes then air can flow in there and dry things out. Otherwise there is a lot of moisture trapped in the exhaust system, which “could“ promote rust on the back sides of the valves and cylinder rust on the cylinder with an open exhaust valve?

 

[FLJetBoater]

I’d say the risk is leaving a lot of standing water in there is more chances of corrosion ... if the water is removed from the boxes then air can flow in there and dry things out. Otherwise there is a lot of moisture trapped in the exhaust system, which “could“ promote rust on the back sides of the valves and cylinder rust on the cylinder with an open exhaust valve?

Found one thread, just from the other day

https://jetboaters.net/threads/not-getting-all-water-out.30938/

 

[FSH 210 Sport]

Found one thread, just from the other day

https://jetboaters.net/threads/not-getting-all-water-out.30938/

Thanks for the link!

I even get a set up to flush with potable RV antifreeze... simple to do after flushing with fresh water... but after reading about blowing out the exhaust, and after talking with Yamaha corporate who said all that is needed is to blow out the exhaust I feel much better about boating when it is cold and towing it home in sub freezing temps. . The only other thing on my boat is to make sure that I drain the water out of the raw water wash down hoses.

At the end of the day I look at it this way. Yamaha spent a lot of time and money doing R&D on these boats to make them reliable, so if I follow the manual I should be good to go. If I can do a bit more to improve it great, but it’s not necessary.

Again, thanks for the link!

 

[swatski]

I had this problem once, water freezing in cooling hoses - thankfully those are plastic and no permanent damage, pretty sure the root cause was not revving the engines up to blow the water out on the lift. I now always do it, usually when pulling out on the ramp while still pitched up - give the engines 2-3 quick revs.
I try not to over-rev when doing it, but I believe water can accumulate in plastic hoses that carry cooling raw water from the pump to the exhaust/engine cooling passages (which self-drain) but water can freeze inside those plastic/rubber cooling lines running low in the bilge.
The Pali heater I have been using since has worked very nicely keeping things from freezing in the engine bay, as long as there is access to shore power or in my backyard.
Here is the original thread:

https://jetboaters.net/threads/freezing-weather-overheat-alarm-fixed.20335/

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[Murf'n'surf]

The sound you describe is on par with a rough idle/run due to bad spark plugs causing misfires. Once your plugs and motor are warmed up, the marble sound disapates.

 

[FLJetBoater]

The sound you describe is on par with a rough idle/run due to bad spark plugs causing misfires. Once your plugs and motor are warmed up, the marble sound disapates.

Interesting. I am close to the 100 hours on these plugs, maybe that was it. Strange thing was it didn’t seem to increase as much as I would have thought when throttle was increased.