Mecruiser 3.0 engine noise

[VRG]

I have a noise in the front of the engine that is like a squeak or moan and lasts only a few seconds, stops and repeats about every 15 seconds. It appears to be coming from the front engine pulley area. My question is can I loosen the belts for the alternator and power steering and still run the engine with the water muffs on the sterndrive and not damage the engine. I would like to do this to see if the noise stops without the alternator or power steering belts
attached to the front engine pulley. does the front engine pulley have a bearing or bushing that might be dry and if so can I grease it?

 

[Bondo]

Re: Mecruiser 3.0 engine noise

does the front engine pulley have a bearing or bushing that might be dry and if so can I grease it?

Nope, just the motors main bearings...

You can loosen the belts,+ start it, but not more than Seconds... In minutes, it'll overheat...

 

[VRG]

Re: Mecruiser 3.0 engine noise

Thanks- i think i will take this to my mechanic and have him check this problem.

 

[VRG]

Re: Mecruiser 3.0 engine noise

I just checked the belt tension on the alternator and it may be too tight. (has about an 1/8" tension gap.) i noticed in the manual it says it should be tightened so it has a 1/2" tension gap. Could this be my problem?

 

[Lodgepole]

Re: Mecruiser 3.0 engine noise

Sometimes a bad alternator will make some wierd noises, bearings or electronics.

 

[fat fanny]

Re: Mecruiser 3.0 engine noise

adj, the belt to the correct tension then listen if the noise persists stop the engine and spray some water displacement formulation #40 on the bearing shafts of the alt, and pump restart and listen if that doesn't do it try a squirt of belt dressing on the pullies also when you adj, the belt take it all the way lose and fell the pullies to all the assesories for a smooth spin if this isn't the case the one that has a glitch may be your culprit! Good luck

 

[Don S]

Re: Mecruiser 3.0 engine noise

Take the belt off and start the engine and see if the noise is gone.
If you have muffs 9(with water) on the drive, you can run the engine for a couple of minutes or more and not overheat anything. Assuming it's raw water cooled, the raw water pump will put water into the engine, may not circulate properly, but it also won't let the engine overheat or burn up the exhaust system. If FWCooled, still no problem, there is coolant around the engine and it will not overheat in a couple of minutes.
If the noise stops then you have either a belt, an alternator, or a cirulation pump problem.
Look at the pulleys, rusty???? Red flag
Turn the alternator and circ pump any rough movenent or noise? Red flag.

 

[VRG]

Re: Mecruiser 3.0 engine noise

This site is great!!! Thanks for all of the replys. When i got home tonight i started the engine and let it warm up and the noise was still there. I loosened the alternator belt and restarted the engine and the noise was gone. So per some of the comments the problem must be the belt, the alternator or the pump. I will try and check this out tomorrow and post what i discovered.

 

[VRG]

Re: Mecruiser 3.0 engine noise

I was going to take this to my mechanic but i called him and he said his turn a round time was going to be 3-4 weeks so i thought i would try this myself with the help from fellow members on this site. It really helped reading the posts on how to take the belts off. I had to remove the front motor mount nut on top but didn't have to take to pulley off.
When i got home tonight i took the belts off and check the pulleys out for smooth rotation and they appear to be smooth. I did notice that the rear bottom connection bolt on the alternator was loose ( not sure if that can cause problems.) the belts are also a little frayed. I am going to go ahead and replace the belts since i have taken them off. I will run the motor tomorrow and see if the new belts make a difference.

 

[VRG]

Re: Mecruiser 3.0 engine noise

I ran the motor today and everything sounded good until it warmed up and the squeak/moan returned. I isolated the noise to the thermostat /water circulating pump area by listening through a screwdriver. I took the thermostat out and started the engine and noise was gone. When i put the thermostat back in the noise returned.
Can the thermostat cause this noise or is it somehow putting pressure on the pump and it is causing the noise?

 

[Don S]

Re: Mecruiser 3.0 engine noise

Replace the thermostat and find out.

 

[VRG]

Re: Mecruiser 3.0 engine noise

Thanks for the reply. I thought about doing that when i first took it out and now i wish i would have. I will change it out this weekend and see what happens.

 

[VRG]

Re: Mecruiser 3.0 engine noise

I changed out the thermostat today and started the engine and the noise seems to be gone. I am not sure why,but does anyone know why the thermostat would cause this noise?

 

[fat fanny]

Re: Mecruiser 3.0 engine noise

Possibly the stat is opening on a angle causing the moaning sound ?

 

[ken_23434]

Re: Mecruiser 3.0 engine noise

I changed out the thermostat today and started the engine and the noise seems to be gone. I am not sure why,but does anyone know why the thermostat would cause this noise?

I am guessing something strange was going on with how far it was opening or angled as mentioned above and the thermostat was acting like a "whistle" as the water passed through it.

Glad it's fixed. MUCH less time than the 3-4 week turn around and probably MUCH cheaper too.

 

[VRG]

Re: Mecruiser 3.0 engine noise

I went to the lake and ran the boat after changing the thermostat and the previous noise from the thermostat area was gone. The one thing that i noticed is that the thermostat now goes up to 180 degrees and then drops back to 160. It never get's any higher than 180. I checked and the new thermostat says it is a 160 degree. Should i be concerned about this or go get another thermostat?