Engine making rushing air sound

[Herbieville]

Mercruiser 5.0 engines both make a rushing air sound at startup. The starboard engine calms down after about 10 seconds but the port engine never does. Engines both run fine with this condition.

I replaced the IAC but the problem did not go away after a day out on the water. The replacement IAC is borrowed and suspect, though.

Any suggestions?

Thanks!

-G

 

[flflatrate]

iac muffler. check other spot you posted this at

 

[GMAN1]

Definately the IAC muffler. Sometimes if the engine backfires it will suck them in. Small square foam piece about 1 inch X 1 inch.

 

[Herbieville]

Re: Engine making rushing air sound (bad IAC?)

I pulled the arrestor off both engines and neither had the foam muffler inside and yet the starboard engine quiets down after about 10 secs whereas the port engine keeps "swooshing". This is all at idle speed. So the absence of the foam muffler does not seem to be a factor. Any other ideas?

Thanks!

-G

 

[flflatrate]

just put the mufflers in some, motors will be worse than others with the swooshing sound. It can't hurt spending $2 for the mufflers that belong there.

 

[Herbieville]

Dropped the mufflers in but the port engine is still making that swooshing sound.

Now the bilge pump is coming on all of the time (every 30 secs) when the engine is running and I can see water bubbling at the back of the engine compartment. This does NOT happen when the engines are off.

Could these problems be related?

Thanks!

-G

 

[Herbieville]

Most definitely -- I am putting in a call tomorrow and will be checking on it as well. I did a LOT of observing and it only happens when the engines are running.

Is it possibly related to the cooling system or the the exhaust system?

I'm certainly not expecting to fix this myself but I am curious what folks on this board think as I have received great info and guidance on this board, including yours!

Thanks!

-G