# 2013 Yamaha 40HP 4stroke tiller - clicking noice



## Smackdaddy53 (Dec 31, 2012)

It’s not under load out of water.


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## ET101 (Sep 10, 2020)

Gatorframer said:


> I hooked it up to a couple hoses (muffs on the lower unit and one on top)


Did you let the motor run while hooked up to the flush port on top? If so, that runs the risk of flipping the impeller backwards from the water pressure flowing reverse. Try running the motor on just the muffs... if you don't get water glow out of the pisser, you may need to replace the impeller.


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## Smackdaddy53 (Dec 31, 2012)

ET101 said:


> Did you let the motor run while hooked up to the flush port on top? If so, that runs the risk of flipping the impeller backwards from the water pressure flowing reverse. Try running the motor on just the muffs... if you don't get water glow out of the pisser, you may need to replace the impeller.


Where did you hear that?


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## ET101 (Sep 10, 2020)

The manual says to never run the engine on the flush hose because damage to the impeller can occur. Atleast on my slightly older f40 manual it says that.


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## ET101 (Sep 10, 2020)

The built in flush hose not muffs.


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## Gatorframer (Feb 28, 2021)

Smackdaddy53 said:


> Where did you hear that?


In the lower unit. I took a video of it but can’t seem to be able to attach it


ET101 said:


> The built in flush hose not muffs.


ok. I did see a video of a captain down here in central FL that uses the muffs and flush port and had no issues. Luckily I only ran it for about 10-15min on idle. Engine was peeing fine and water temp felt really cool. Guess I won’t be doing that anymore.


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## Rick CFM (Jan 22, 2021)

The impeller is not gonna flip backwards from the water pressure. Anyone who told you that was blowin smoke. As long as you have enough water pressure and you let the hose run long enough to get water flow out the lower unit your fine. Do you have a stainless prop, if you do then The noise your hearing is prop chatter. Especially if it goes away when you give it some throttle.


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## Jessincase (Mar 9, 2021)

The clicking is caused by the weight of the prop on the shaft causing the gears to chatter. It's a very common and known issue on yamaha four strokes in all horsepower groups.


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## Rick CFM (Jan 22, 2021)

Jessincase said:


> The clicking is caused by the weight of the prop on the shaft causing the gears to chatter. It's a very common and known issue on yamaha four strokes in all horsepower groups.


It's no the gears it's the spines of the prop shaft against the splines of the prop.


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## Jessincase (Mar 9, 2021)

Rick CFM said:


> It's no the gears it's the spines of the prop shaft against the splines of the prop.


Sorry, that's not correct. Even if the prop is not properly torqued, the tolerance on the splines is closer than that. On engines with rubber hubs (smaller outboards), the sound is entirely internal from the lower unit. On larger engines, the sound is from two sources--the prop hub on sds props only, and from the gears due to backlash. None are harmful, just an annoyance.


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