Cooling water impellar replacement

[John Greenlund]

My boat mechanic says that my starboard engine is overheating with extended idling because the rubber impellar needs to be replaced. I have no idea how old it is as I got the boat used. At speed or short idling periods it runs fine. Is it a big deal to replace them? I have pulled the drive out once to clear a chunk of wood but haven't gone in any deeper than that.

 

[McMark]

There are no rubber impellers. Maybe need thermostats or a descaling? Clean out the little strainer where the cooling water enters maybe?

 

[Scottintexas]

because the rubber impellar needs to be replaced.

I'd ask him to see the part # on the schematic for that, or I probably wouldn't even go back, you're better off with a jetski mechanic,

Did the previous owner use the boat in salt water?
Do you have all four indicator holes pumping water at speed,
Do any of the clamps in the engine bay look rusted?
How long is "extended idling"? 2 minutes, 5minutes, 20 minutes ?
Do you have shutoff valves installed?
What is your oil level at?

You might want to consider buying a YDS unit to read your engines and help diagnose on the water,

 

[John Greenlund]

Thanks for the insight McMark So where or how does water get circulated without impellars? Here in the picture is what I assume is the water intake which is clear.

 

[boudin]

Agreed. If the mechanic thinks the boat has an impeller for cooling, then you need a new mechanic. There is no cooling impeller on the Yamaha boats. He's going to be throwing parts at it.

Intake strainer is going to be that little rectangular box on the side of the pump.

-Greg

 

[Neutron]

Thanks for the insight McMark So where or how does water get circulated without impellars? Here in the picture is what I assume is the water intake which is clear.View attachment 78623

That is your exhaust outlet

 

[John Greenlund]

The boat was previously owned in Wisconsin and is super clean with no sign of salt water useage. No rust on the clamps and both pee holes are pumping water fine. The only time it showed over heating was at the dock after about ten/fifteen minutes and when I winterized it in the driveway as I was flushing it with antifreeze. Running it normally there doesnt seem to be a problem. A YDS should help me figure out what is going on.

 

[Scottintexas]

the video above should be a great help to you,

running on a hose isn't uncommon to throw a temp warning as the water pressure at some homes isn't enough or people use a splitter to try to do both at once even further reducing pressure,

if you only had one other overheat occurrence around your dock I wouldn't worry about this problem until it shows up 4-5 more times while on the water, theory is that the engines actually cool better at higher rpm because they're getting more water pumped through them than at idle or no-wake speed,

 

[John Greenlund]

I see the screen now. So the next step is to check/clean the screen by accessing it from the outside as shown in the picture?
Thinking back on my brief conversation with my mechanic who is very fair and honest I think he was probably thinking about my Bayliner not my jet boat.

 

[Scottintexas]

yes but it's the inside of the nozzle portion where the screen that it sucks water from and that needs to be clear, you don't have to take that apart unless you see some indication, it probably won't have anything noticeable on it, I would run it again at the lake and intentionally leave it at idle to see if you can duplicate it, I'm thinking you won't, there probably just happened to be something in the impeller or screen that just happened to be enough to cause an issue and then was blown out when you increased rpm's.

It's good you have someone you have faith in for maintenance, being big jet skis some boat mechanics aren't familiar with issues like cleanout plugs, cavitation or loose silicone and end up leading people down an endless road of fixes or over filling the oil,

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[Scottintexas]

at the :59 second mark in the video is what needs to be clear,

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[John Greenlund]

Thanks everyone for help and explanations. I'll watch for any overheating issues but when running it normally for almost a week after the overheating incident I had no problem. I feel better now!

 

[Scottintexas]

the simplicity of our boats is great but they do have their issues that you have to be aware of,

being a 2011 be sure to keep an eye on your oil coolers if they haven't been upgraded,
from our FAQ
https://jetboaters.net/faq/1-8l-eng...r-missing-a-bolt-or-dripping-misting-oil.120/




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[John Greenlund]

Dang. Thanks for the heads up on the oil coolers. Sure enough, both my number 3 bolts are missing. There is a miniscule bit of oil on the bottom of each but that may be a remnant from the last filter change. I'm not quite yet at 100 hours. I'll clean the bottom of each and then monitor them.

 

[Julian]

Thanks everyone for help and explanations. I'll watch for any overheating issues but when running it normally for almost a week after the overheating incident I had no problem. I feel better now!

My guess is that you picked up some weeds and this was what caused your cooling issues. It can't hurt to pull of the square caps of the intake strainers just to check that you don't have some obstruction in there (its good to get to know the inner workings of your boat anyway- and this is an easy check to make).

 

[boudin]

...pull of the square caps of the intake strainers just to check that you don't have some obstruction in there

Okay because you are from MO and a freshwater boat. Don't try this with a saltwater boat without plenty of heat. Those 10mm bolts on the strainer snap easily.

-Greg

 

[Julian]

Okay because you are from MO and a freshwater boat. Don't try this with a saltwater boat without plenty of heat. Those 10mm bolts on the strainer snap easily.

-Greg

Which reminds me....I should remove mine since I was in salt water just to be sure they don't sieze in place. This is regular maintenance that all salt water boaters should probably do yearly - remove the pumps and any external fixtures that they might want to remove in the future. Probably is something that Yamaha should include in their service manual for salt water boaters. @Cobra Jet Steering LLC curious if you do this routinely, or if you dismantle yours regularly enough not to need to?

 

[boudin]

I use a light coating of marine grease on all pump, pump shoe or ride plate bolts.

I'm sure there are differences of opinion here, but IMHO I think you are asking for trouble removing them just for the sake of removing them. I would just wait until you need to, and then use plenty of heat.

-Greg

 

[Cobra Jet Steering LLC]

I rinse my pumps vigorously after each outing, I also use zinc in several places around the pump and ride plate and spray everything except the anodes with white lithium grease.
If you want to prevent bolts from sticking use bees wax it works better than anything I have used and it is readily available and inexpensive , I use it for sanding and grinding aluminum also .
Bees wax is commonly found in the pluming section of your hardware store, they make toilet bowl base gaskets from it . truth is stranger than fiction, I always used that wax on my outboard water pump impellers as well because water won't wash it off.