Please Help | Mercruiser 350 Making Weird Noise

[MikeyD123]

Hello all,
I have a mercruiser 350 with the 4 bolt main, first a description of how I got to where I am. I had a new shift cable installed by the dealer. I then took the boat out to test the shifting. while I was out my alternator gave out and the boat died as i brought the RPM's down. Had saea tow bring me back to dock. I then brought my boat home put a spare battery and flushed out the engine as it is raw water cooled. I installed a new alternator and it is charging now. Here is the problem, after about 5 min. there is a light buzzing or whistling sound that gets louder as the engine runs. It never did this before. It appears that the sound is coming from the solenoid for the starter where there is a reset circuit of some sort. Can anyone help me?

 

[Maxz695]

Re: Please Help | Mercruiser 350 Making Weird Noise

This is a merc outboard section and this would be better moved the proper section for I/O

 

[QC]

Re: Please Help | Mercruiser 350 Making Weird Noise

I moved this over to the Mercruiser section. Good luck Mikey. Maybe add a little more info about the vintage, horsepower etc.

 

[Don S]

Re: Please Help | Mercruiser 350 Making Weird Noise

It appears that the sound is coming from the solenoid for the starter where there is a reset circuit of some sort.

I have heard failing circuit breakers buzz before. Always replaced them before complete failure.

 

[MikeyD123]

Re: Please Help | Mercruiser 350 Making Weird Noise

I have heard failing circuit breakers buzz before. Always replaced them before complete failure.

Don, did is sound like a increase in the loudness of the sound or was it constant. The sound I am hearing starts out low and then builds up to be louder and louder. Any advice would be much appriciated.

 

[Fishermark]

Re: Please Help | Mercruiser 350 Making Weird Noise

Noise can be a funny thing and sometimes hard to tell exactly where it is coming from. I would suggest taking off the front drive belt and see if the noise disappears. If it does, I would suspect the alternator. If it is still there it may be easier to isolate at least.

 

[MikeyD123]

Re: Please Help | Mercruiser 350 Making Weird Noise

Noise can be a funny thing and sometimes hard to tell exactly where it is coming from. I would suggest taking off the front drive belt and see if the noise disappears. If it does, I would suspect the alternator. If it is still there it may be easier to isolate at least.

I went ahead and took off the front belt and the sound is still there, I was thinking it might be a vaccum leak possible from the carb. Does this seem like it could be possible?

 

[Fishermark]

Re: Please Help | Mercruiser 350 Making Weird Noise

spray some WD-40 around the base and see if the idle speed changes.

 

[MikeyD123]

Re: Please Help | Mercruiser 350 Making Weird Noise

spray some WD-40 around the base and see if the idle speed changes.

I found the problem, It was a vacuum leak in the intake manifold. Looks like the low cost mechanic i paid to rebuild the engine didn't quite do it right. Thank you all for your help. Happy boating!!

 

[MikeyD123]

Re: Please Help | Mercruiser 350 Making Weird Noise

I do have another question. What would or could happen if I just put say JB weld on the outside of the intake manifold to cover the gap where the seal / gasket is letting air in?

 

[Don S]

Re: Please Help | Mercruiser 350 Making Weird Noise

Will a band-aid fix a broken leg?

 

[jimmy wise]

Re: Please Help | Mercruiser 350 Making Weird Noise

Before you make a mess by trying to jury rigging it call the mechanic that did the work. It may be simply retourqing the manifold

 

[Fishermark]

Re: Please Help | Mercruiser 350 Making Weird Noise

JB Weld is a great product and has its place... fixing a vacuum leak because of a wrong / incorrectly installed gasket is not one of them.