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150HP 4-stroke rattles with big prop

B

bbelk

New member
First timeposter, so I hope I do this right.

I put a newpropeller on my 2004 Yamaha 150HP 4 stroke. It rattles and shakes in gear at an idle (forward or reverse). The shake clears up as soon as I advance the throttle a little.

The propeller guy says there is a Bulletin out on itand that there is a fix, but he didn't know what it was.

It is quite bad with the new 16 inch prop. It was present, but greatly reduced with the old prop which was worn down to 13.5inches. Does anyone recognize this issue and have a solution.

Thanks
Brad
 
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Im interested in this, as my buddy has the same issue on a 2010 150hp 4 stroke. he is running a four blade stainless turbo prop.

will
 
Yamaha has branded "THE CLUNK" of which you are speaking about. However the F150 never seemed to be that bad. Has your gearcase been worked on? If so then the tech may of put a two stroke clutch dog in it, and that will certainlly sound "the clunk". That 16 inch diameter prop is not helping either. Thanks Martin
 
mcyama said:
Yamaha has branded "THE CLUNK" of which you are speaking about. However the F150 never seemed to be that bad. Has your gearcase been worked on? If so then the tech may of put a two stroke clutch dog in it, and that will certainlly sound "the clunk". That 16 inch diameter prop is not helping either. Thanks Martin
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This rattle is not THE CLUNK, which is certainly there. This rattle happens in forward or reverse at dead slow and it continues until the speed is raised.
 
Merc has a flow torgue adapter for the 40-60 hp engines for the rattle problem....its a prop problem.....the web has a lot of entries on prop rattle on both mercs and yammys in the 150 hp range....its confusing as hell.....some say dont worry about it but thats hard to do...i have a 60 with the problem and intend to have a go with the dealer that sold it to me when i get the boat back in the water...i have a camp on a canal and hear mercs rattling when at slow idling speed all the time....the 4 cycles....it may be just more noticable on 4 cycles because they are so quiet when running...but its a metal to metal sound that i dont like...lets keep this problem open and see what develops....
 
I would look at the symetry of the blade to see if it's not bent.Then I would take that big prop off and go with something that will allow the engine to turn5300-5500 rpm WOT.
 
OK to start with you have a lot more mass in the new prop so it won't respond to momentary acceleration and deceleration of the propshaft at idle. What you may be hearing is driveshaft hop. This can be exacerbated by imbalanced throttles or too low of an idle speed.
The other thing to be aware of from a motor longevity perspective is that your motor needs to be able to turn 6000 rpm. If you have a prop with too much pitch or diameter it can make the motor lug in the mid range and incur possible detonation. From my experience the F150 lives best with 14 1/2" diameter props.
 
moonman60 said:
I would look at the symetry of the blade to see if it's not bent.Then I would take that big prop off and go with something that will allow the engine to turn5300-5500 rpm WOT.
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Two brand new props have done the same thing. With the one I kept, I can reach 5500 in most any configuration and 6000 at full jack and trim.
 
PBRMAN said:
OK to start with you have a lot more mass in the new prop so it won't respond to momentary acceleration and deceleration of the propshaft at idle. What you may be hearing is driveshaft hop. This can be exacerbated by imbalanced throttles or too low of an idle speed.
The other thing to be aware of from a motor longevity perspective is that your motor needs to be able to turn 6000 rpm. If you have a prop with too much pitch or diameter it can make the motor lug in the mid range and incur possible detonation. From my experience the F150 lives best with 14 1/2" diameter props.
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Are you suggesting that the when the motor speed reduces between piston strokes at an idle, the prop's mass causes it to NOT slow down and it lifts off the shift dogs?

Is this something different than driveshaft hop?

Is the prop diameter limitation written down anywhere by Yamaha?

Thanks
 
Just less able to respond to torsional variables period. Hence the entire gear train loads and unloads. With regards to diameter you won't find anything written but you can infer from the fact that Yamaha developed the smaller diameter props about the time the F150 came along. Imprinted in my brain however is the experience of dealing with powerhead/piston problems on this motor and others where lugging is a common thread and cntributed to by overpropping.
If your motor is on a light boat maybe you will never have a problem but the rpm you get in a jacked mode isn't a true representation of the load on the motor with jack plate down and cruising with the prop fully engaged. How well are those throttle bodies synched?
 
PBRMAN said:
Just less able to respond to torsional variables period. Hence the entire gear train loads and unloads. With regards to diameter you won't find anything written but you can infer from the fact that Yamaha developed the smaller diameter props about the time the F150 came along. Imprinted in my brain however is the experience of dealing with powerhead/piston problems on this motor and others where lugging is a common thread and cntributed to by overpropping.
If your motor is on a light boat maybe you will never have a problem but the rpm you get in a jacked mode isn't a true representation of the load on the motor with jack plate down and cruising with the prop fully engaged. How well are those throttle bodies synched?
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Dealers here in Austin don't seem to know anything about the issue. A dealer near the coast, where manhood is defined by the size of your prop says this (approximatly)

"All 150 HP Yamahas rattle at idle if they have big four bladed props. There is not a fix, but the rattle does not hurt anything. It can be greatly reduced or eliminated with a smaller propeller but many coastal fisherman live with it rather than give up the performance."

This alignes with my experiance and your comments. I understand prop pitch and I am not over propped. I can reach 5500 at any reasonable trim/jack and can reach 6000 at full jack, which I do end up using often.

Regarding the throttle balance: Is there an adjustment that is different for idle vs power on? It idles very smoothly in neutral.
 
Sounds like you are balanced fine. If you want the big prop then you get to live with the rattle. Obviously boats are lighter and push a little easier where you are. I'm sure you can get away with a bigger prop for awhile. It's usually not a problem until after 1000 hrs. Premium fuel helps though.
What I have found though is that motor has a good life if you use it's rpm not it's mid range torque and maybe that is how you folks run. Hard for me to know what goes on in all the other worlds.
 
PBRMAN said:
Sounds like you are balanced fine. If you want the big prop then you get to live with the rattle. Obviously boats are lighter and push a little easier where you are. I'm sure you can get away with a bigger prop for awhile. It's usually not a problem until after 1000 hrs. Premium fuel helps though.
What I have found though is that motor has a good life if you use it's rpm not it's mid range torque and maybe that is how you folks run. Hard for me to know what goes on in all the other worlds.
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I know you are trying to tell me something and I just ain't getting it. I have 800 plus hours on the motor so your input intrests me. If I can reach full RPM, what is it about the prop that you think will shorten the life.

I do cruise at 4000 - 4500 (28 - 32 MPH) a lot. The motor is very responsive and doesn't feel at all slugish. Its just a pleasent speed and I am usually not in much of a hurry. Also, as you say, flats boats are different. Not because its light. My boat is heavy as hell, because of its thick hull and it is full of floatation. It is very broad and flat so it comes out of the water in a hurry and floats shallow. However, when its up on top, there is a large amount of hull in the water, making them very inefficiant cruisers. Speed makes it worse. With a light load and fully trimmed I can hit 40 MPH. The motor is working hard for those last 8 MPH and it is louder. In tests, when I have go to less pitch I start losing top end and the max RPM doesn't go up any. Too much pitch and I can still hit 40, but its at around 5000 RPM at full throttle and the boat is very sluggish at low speeds.

So my question is, in your opinion, am I shortening my motor life by not pushing it to 5000 when cruising?
 
two questions.....do you hear any rattle when in nuetral at idle?....any at all?....2nd question is 4 stroke vs 2 stroke on motor life as related to running rpms...i understand why a 2 stroke should be run near or at max rpm....what is wrong with running a 4 stroke (cruising) at 1k rpm below rated rpms?
 
My two cents again. If you can get 6 K and you run at 5 K your motor will be a lot happier than if your max is 5500 and you run at 4500. Happy motor happy wallet. Happy wallet happy wife. Happy wife happy life.
 
papyson said:
two questions.....do you hear any rattle when in nuetral at idle?....any at all?....2nd question is 4 stroke vs 2 stroke on motor life as related to running rpms...i understand why a 2 stroke should be run near or at max rpm....what is wrong with running a 4 stroke (cruising) at 1k rpm below rated rpms?
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Idle is whisper quiet and rattle free. I don't know the answer to the second question.

PS: I was raised in Baton Rouge. Mom and sister are still there.
 
PBRMAN said:
My two cents again. If you can get 6 K and you run at 5 K your motor will be a lot happier than if your max is 5500 and you run at 4500. Happy motor happy wallet. Happy wallet happy wife. Happy wife happy life.
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Here is my new theory, developed during this discussion. The big broad flats boat feels to the motor like a little boat untill you try and go fast. I can put 4 three hundred pound fisherman on the boat and it still pops out of the water. Because of the hull shape, the drag goes way up at speed compared to a normal boat. Under this theory, the motor is not lugging at 30 MPH and 4100 RPM, even though it can't reach 6000 at 38 MPH full throttle. I get the last 500 RPM and 2MPH by jacking the motor up into the tunnel above the main hull.
 
You have a good understanding of what is going on with your hull. I suspect that flats boats maintain a lot of wetted surface and may also be slightlly hooked to enable the quick plane but can't get loose. So probably is sliding along fairly easily. If you get a chance to try a Yamaha 15 or 17 pitch Reliance series prop it is a good match up on that motor.
 
No BBelk,What PBRMan is saying is ON in my Experience.He sounds like an Old Commercial Fisherman to me.From your thread it sounds like there is too much prop when you get to 40 mph and 5000 rpm. Sounds like a 16" diam. @ 19 pitch.If you lower the pitch you can turn that Big wheel (16") but if you put a smaller diameter, say 14.5 -15" and the engine turns 6000rpm's fully engaged tilt down there is no way to know if you aren't wasting efficiency.The spark retarder may be keeping the engine at 6000 rpm.
That is good for the engine like PBRMAN say's because the motor isn't being STUFFED or STRESSED.I am a commercial recreational fisher and I get good results ie)good take off,not much rpm fluctuation with a load etc. when what ever size engine can turn 200 to 300 rpm's less than maximum rpm rating.
 
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