Serious shaking of 3.0 Merc on start up.

tunawish

Recruit
Joined
Jul 15, 2008
Messages
2
Hi,
I have recently purchased an older boat with a newer 3.0 LX Merc Alpha I
Gen II package..
I believe it to be a 97 or 98..very few hours, well maintained and starts and runs well and smooth after warming up....
Anyway I have 2 issues... they may be related.

1) I found pieces of the inside transom bracket (bottom corners) in the bilge when cleaning it out. They are from the new package not from the original as I had hoped. My mechanic said this is not uncommon due to many mechanics over torquing the bolt or a transom not being parallel. He said they were not a structural attachment and aside from water possibly leaking in, would not worry about it for now...??

2) Upon start up the engine shakes, what I would call severely until warmed up. The bolts, spacers and washers at the rear mounts appear to be intact as far as I can see..I cannot get to the bottom nuts as they seem to be encapsulated by the casting in the bracket...Mechanic again without seeing it indicated these 3.0's exhibit a lot of movement until warm due to the 4 cyl and the 3 point mount...

Does this sound normal, Although I've had 6 boats in my life I haven't had a four banger in a boat for over 20 years so I have nothing to compare it with...

Thanks
Ray
 

Holy Smoke

Cadet
Joined
Jul 15, 2008
Messages
16
Re: Serious shaking of 3.0 Merc on start up.

spark plug and wires are good? Dist. cap? Could it be related to a cold start. And not the motor mounts?
 

Alumarine

Captain
Joined
Feb 22, 2005
Messages
3,695
Re: Serious shaking of 3.0 Merc on start up.

What RPM is it trying to idle at when doing a cold start?
 

tunawish

Recruit
Joined
Jul 15, 2008
Messages
2
Re: Serious shaking of 3.0 Merc on start up.

I usually keep at it at 12-1500 till she warms up
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Serious shaking of 3.0 Merc on start up.

Sounds like the choke is too tight. For a test, turn the ign. switch to the run position and see if the choke plate starts to open. When it opens to abour half, start the engine and see idf it runs smoother.
 

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: Serious shaking of 3.0 Merc on start up.

You got electric choke in that ole girl. They shake till warmed up, no getting around that. But you should not go over 1200 rpm when starting it. 1000 better still. Should idle after warm in gear between 650-700, on the water.
 
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