3.0L Merc Aplha 1 Outdrive Rattle?

[Wetbehindears]

97 Merc 3.0L 18ft Runabout, Alpha 1 outdrive.
During boating all day on the water, boat ran great, no problems, no noises.
While flushing on the ears, the outdrive (not in gear) sounded like a rattle.
Example: like loose exhaust on an old car.
If you rev up in neatrual, the rattle follows the rpm's.
If in gear, no rattle!
Any ideas?

 

[Haut Medoc]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

Are you sure it is the drive & not the exhaust shutters?....JK

 

[Wetbehindears]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

"Almost" pretty sure!
I took an automotive stephascope (probably mis spelled) and worked my way around the motor and onto the outdrive. I will be honest, I have owned Outboards before, this is my first inboard, so besides plugs, caps, rotor, etc... I have really never done any repairs to the boat.
Anyways, It sounded as if it were coming from the upper section of the outdrive.
I dont think my boat even has exhaust shutters? It may.. the exhaust exits up under my outdrive, so I really have never stuck my head up there to see.

I dont some research online while checking back for an answer. I read of a guy with a similar problem, and his only did this with his outdrive in the Trailer postion. Unfortunately, he never posted what the conclusion was. I only noticed the noise while flushing with the engine in the UP or Trailer postion. On the water, she was quiet.

 

[stevieray]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

There's your problem...drive should not be run above the trim limits. Rattle you are hearing is the u-joint operating out of its normal range. How long did you run it that way & at what RPMS?

 

[Wetbehindears]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

for a 15 min flush.
Only in gear for maybe a min, just to see if it still made the noise.
Ran at idle, but did rev up a couple of times to see if the noise changed.
I have not tried to run in the down position while on the ears yet to see if its still there!

 

[stevieray]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

When you flush it next time, make sure it's as far down as you can get it without ramming the skeg into the ground - that should be within the limits of the trim switch. Only use the trailer swich when engine is off. Take it out & run it down & trimmed up like you would normally run & listen for that noise when you turn it way port or starboard. If it is noisy, you may need to replace the u-joint & possibly the gimbal bearing since that will sometimes go bad along with the joint.

 

[kbetts]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

I'm with Stevieray on that one. The noise you were hearing were your u-joints on your drive shaft inside your outdrive in a bind with the engine coupler and the gimble bearing. That was a mouthful. Run on muffs anywhere between up and down position, not in the trailer position. Welcome to the stern drives!!!

 

[Fishstick1962]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

When I first got my I/O the previous owners didn't have the trim limit switch adjusted right, and being new to I/O I didn't know any better... long story short...running engine with Outdrive in trailer position cost me $560 in parts and repairs. Check trim limit switch setting!!!!! Very easy adjustment can save lots of grief and $$$$$!

Happy boating!

 

[jamesr1]

Re: 3.0L Merc Aplha 1 Outdrive Rattle?

"While flushing on the ears, the outdrive (not in gear) sounded like a rattle"


Have you re-tried this with the outdrive down?

Kinda sounds like its not coming out of gear all the way.