4.3L mercruiser rattle

[luckylot13]

I have a 1997 VIP deckliner with a 4.3L mercruiser. When I get to 30mph, I hear a rattle coming from the engine. Not sure whether it is internal or something external? Any help figuring out what it is would be greatly appreciated.

 

[Haut Medoc]

Re: 4.3L mercruiser rattle

Welcome to iboats Like lifter rattle? How is your oil pressure? The best thing to do would be to take it out on a nice calm day & have someone else drive while you try to isolate it....<br />It is hard to diagnose a noise without actually hearing it.....<br />Can you get the noise on the muffs?<br />Did it always make this noise or is it new.....JK

 

[luckylot13]

Re: 4.3L mercruiser rattle

Oil pressure, temp, is normal. I have only had the boat 1 month. If it was lifter rattle would it do it all the time or under more stress?

 

[luckylot13]

Re: 4.3L mercruiser rattle

The noise sounds more like a bracket rattle. When I am getting the boat up to speed or to plane, it also makes the noise. I have tried to listen once I get to 30 or more but when I raise the engine cover its to loud to isolate the noise.

 

[Haut Medoc]

Re: 4.3L mercruiser rattle

Will it make the noise on muffs?<br />Have you checked the timing?<br />Didn't you ever own a car that made noise when you punched it?<br />I would poke around & see if anything was loose(engine off)...<br />Sometime things will rattle at different speeds due to harmonics.....<br />Being under load can affect that, too.....<br />That is why I ask if you can recreate it on the muffs.....JK

 

[luckylot13]

Re: 4.3L mercruiser rattle

I haven't tried to recreate it using the muffs yet. It's hard because I store the boat at the lake on a shelve, so it's hard to do what I need to when I want to. I have not checked the timing either. I am not the most mechanically inclined person.