merc. knock noise

[tystick]

I have a 1990 4.3L merc. with alpha 1 - is it normal to hear a knocking noise only when prop is in up position? I noticed it while in idle and it goes away as soon as i lower prop. I was thinking time to check gimbal bearing but not sure<br /><br />Also, is there an alternate to anti seize compound ie: greese? I have to finish a starter job and do not have anti seize.

 

[Don S]

Re: merc. knock noise

DO NOT run the engine with the drive in the up position. <br /><br />Use grease on the prop shaft, not EVER seize.

 

[Bondo]

Re: merc. knock noise

Ayuh,...... Any Higher that the trim position is putting Extreme Stresses on the U-Joints,+ Gimbel Bearing,........<br />'Course it's Knocking,........ Don't Do It............<br /><br />If you're worried about Never-Siezing the Starter Bolts,.........<br />Ahhhh,.......<br />Try This,......<br />V<br />V<br />V<br />V<br />V<br />V<br />V

 

[tystick]

Re: merc. knock noise

vvvv?

 

[tystick]

Re: merc. knock noise

I occasionally have to get thru shallow waters where i have to lift prop slightly to go but I never go fast ...just enough to move.<br /><br />Actually, there is slight knock in prop down position - only when increasing rpm from idle. It goes away at idle. <br />It sounds like the gimbal is going? Can you run like this or is risk of other issues? <br /><br />Also, PO left anti theft prop lock with no removal socket. Now what?

 

[Bondo]

Re: merc. knock noise

Originally posted by tystick:<br /> vvvv?

Any Grease is Better, Than No Grease At All...

 

[Don S]

Re: merc. knock noise

You probably have ujoint problems, not gimbal bearing problems.<br /><br />

Can you run like this or is risk of other issues? <br />

If the gimbal bearing locks up, the transom shield will be damaged beyound repair, if the ujoints come apart it can take out the transom shield and the drive.<br />Do you feel lucky?

 

[tystick]

Re: merc. knock noise

don, <br />what makes you think ujoint problem instead of gimbal bearing? From what I can read in archives, ujoint issues seem to be related to hard steering left or/and right.<br /> <br />I am all set for gimbal replacement so will check ujoint. What to look for? <br />What is the link for the ujoint install?<br /><br />Any ideas on prop lock problem?<br /><br />thx robert

 

[tystick]

Re: merc. knock noise

Originally posted by Don S:<br />[QB] You probably have ujoint problems, not gimbal bearing problems.<br /> I am curious why you said this. Please enlighten me

 

[Don S]

Re: merc. knock noise

Experience. <br />Gimbal bearing usually make a rumbeling noise all the time and it gets worse when you turn.<br />Ujoints when worn out make a knocking noise.... In most cases<br /><br />Prop Lock??? Geeezzzz, I don't even lock my house, truck, or boat, how do you lock a prop?

 

[tystick]

Re: merc. knock noise

this is not Ketchikan AK. <br /><br />I am in a place called NY where props have been know to walk by themselves even with bad ujoints!!!!!!!!!!!! <br /><br />Similar to an auto - lock is attached to one stud, a special socket comes with theses stud loakc for removal.<br /><br />Would ujoints only make knock noise when turning?<br /><br /><br />Don, <br />Does mercstuff or anyone else have a "how do I" section on ujoints? I see the gimbal bearing but not ujoint.<br />thx robert

 

[tystick]

Re: merc. knock noise

this is a bump

 

[Don S]

Re: merc. knock noise

I am in a place called NY where props have been know to walk by themselves even with bad ujoints!!!!!!!!!!!!

When you say prop, do you mean the complete drive? A prop is just the thing with the blades on it that spins and makes the boat move.<br /><br />

Would ujoints only make knock noise when turning?<br />

They could, just depends on how bad they are.

 

[tystick]

Re: merc. knock noise

OK, outdrive is what i should have said. I always thought money is what made a boat move!! <br /><br />Anyway , I still have a lock on drive that is the issue. Any auto guys will know what they are. In fact , they are commonly sold in boat stores so somebody besides Don who doesn't lock anything knows the answer.

 

[Richard Petersen]

Re: merc. knock noise

A small hand grinder is the only safe way I know to take off lockable nuts. Do not torch it. Rubber prop hubs and shaft seals can be ruined. Grind, turn, grind, it will safely come off.

 

[tystick]

Re: merc. knock noise

Wouldn't a bent shaft have these vibration symptoms at all rpms? Can i rule out ujoints if the vibration occurs when boat is stationary - no steering? <br /> <br />Actually i believe it is a slight shudder or vibration after engine warms up a bit at about 2000 rpm and will stop above or below that. Funny that it does not occur at start up - only after running a while.