Merc 150 2 Stroke Carb Clanking Noise at Idle Maybe Coming from Lower Unit

Status
Not open for further replies.

cvflyer

Cadet
Joined
Feb 2, 2015
Messages
19
I have a 1999 2 Stroke Carb Merc 150 HP. Ran 14 miles offshore the other day and everything was great. Ran back in and when we slowed down to idle, the engine was making a metal clanking noise. As best I can tell it is resonating up from the lower unit. The noise is sporadic and not rhythmic which leads me away from a cylinder or anything top side. The clanking noise can be heard while at idle in gear, reverse or neutral. Once I increase throttle the noise cannot be heard (it might still be there just covered by the engine noise). When I hear the clank it also seems to briefly bog the engine down.

I spoke with my mechanic and he thinks it is the pinion gear in the lower unit. I dropped the lower unit and turned the drive shaft by hand and did not hear anything. The only abnormality I noticed was the drive shaft had some play moving it side to side with light pressure and would make a similar clanking sound.

Is there any easy way I can verify a damaged pinion gear without removing the prop shaft? Has anybody had a similar experience? Also, would it be possible to still engage the prop shaft if the pinion gear was damaged and making that noise?

Any thoughts, help, insight, or comments are greatly appreciated!
 

leonreno

Seaman Apprentice
Joined
Mar 17, 2011
Messages
36
Could be the exhaust tuner in the midsection, they can come loose and clang around. To check, drop lower unit and with a flash light and long screwdriver or metal rod, feel around and see if exhaust tuner is loose. If it is the powerhead has to come off to bolt it back down.

woops, just posted to a 3 year old post, not sure how that happened.
 
Last edited:
Status
Not open for further replies.
Top