Yamaha F150 chatter at low RPM

[chillman]

Have a new to me 2004 Yamaha F150. I get a chatter at low RPM, In gear just out of neutral. smooths out and is fine just above idle. I have read that this could be prop chatter. I have also read it could be from not pulling the shaft upward when installing new waterpump impeller. I didn't notice it during the sea trial but we didn't do much idling around. I just did a full service including the waterpump and did not know about pulling up on the shaft when installing the impeller. I dont mind taking the lower unit back off to try to reinstall the waterpump but more people tend to lean toward prop chatter. Has anyone else experienced this and what did you do to correct it. Thanks in advance.

 

[got_em_on]

We experienced this when we upgraded to Merc rev 4 props which were heavier than the old aluminimum factory props.

Added mercury Flo Torq IV hub kit and they smoothed right out.

 

[chillman]

can this kit be used with the yamaha stainless props

 

[got_em_on]

not sure-you may need to search the mercury website for the specs on it to see.

 

[Luv2fish]

Mine does the same thing. If I kick it in to neutral then back to low idle in gear it stops. I think mine is back pressure from the boat moving faster than the prop speed. I get it when I slow down.

Steve

 

[mrfunandson]

same here, when slowing down to idle speed i get it.

 

[chillman]

Curious as to what props you guys with the problem have. I just got the boat and it has a stainless 15 1/4 X 15 Prop. Looking at yamahas performance bulletin they are using a 13 3/4 X 17 and getting good numbers. From the research I have done the noise is from the large heavy stainless props but switching to a smaller prop will correct the problem. Curious if you are running the smaller prop and still having the noise.

 

[DaleH]

Looking at yamahas performance bulletin they are using a 13 3/4 X 17 and getting good numbers.

One cannot trust ANY performance bulletin from ANY motor brand, as most are tested with "lightly equipped" hulls that are not representative of the real world. As long as YOUR motor achieve maximum RPMs about 200 off the OEM maximum specs ... you are good to go.

Most boats wear too steep a prop (2" higher number in pitch) that it should wear and most OBs are mounted too deep to boot ...

 

[Luv2fish]

I have a stainless steel prop but I'm not sure of the size. I'll check it out and let you know.

I get within 300 rpm of max but only occasionally as I don't run the boat that way most of the time. I usually try to finish the day with a WOT run just to clean out the system.

Steve

 

[captbone]

Double check it is not an issue with the harmonic balancer.

http://www.thehulltruth.com/boating-for ... cer.html#b