Mercruiser 7,4L MPI 2000 IAC muffler / hissing noise.

[Fibr]

Hi , I have the strong hissing noise as many others have from the air intake , but I can?t find any drawings on the engine that shows the foam muffler , I can findt it on other engines , 5,0 MPI , 5,7 MPI and so on , do anyboby know if the 7,4L MPI has got the muffler and where to put it ?

Engine se.no. 0L691258 model no. 4542077N1
7.4 L MPI BRAVO GEN VI - L29

/Finn

 

[Don S]

Re: Mercruiser 7,4L MPI 2000 IAC muffler / hissing noise.

Your model didn't have them, and it's not something you just add on.

 

[Fibr]

Re: Mercruiser 7,4L MPI 2000 IAC muffler / hissing noise.

Thanks , any known tricks to dampen the hissing noise from this type of engine ?

 

[Mischief Managed]

Re: Mercruiser 7,4L MPI 2000 IAC muffler / hissing noise.

Thanks , any known tricks to dampen the hissing noise from this type of engine ?

I find it gets less noticeable when you throttle up and cruise around. ;-)

Mine is impossible to hear at idle speed unless I have the engine hatch open, I assume due to the sound-proofing material that was factory applied. You could add (more) noise insulation to your engine compartment. It's a nice upgrade in general. See: INSULATION BARRIER 1X32X54 - Soundown IVF1010MNSFT12 - iboats

 

[dubs283]

Re: Mercruiser 7,4L MPI 2000 IAC muffler / hissing noise.

any known tricks to dampen the hissing noise from this type of engine ?

is the pcv valve line connected??