I/O Mercruiser 350 - belt chirp and oil sheen

[MDseacraft]

I have two issues I am chasing down:

1) I have a belt chirp. Belt looks to be in great shape - no sign of rubbing. Chirp increased with rpms. Not chirp when the belt is off. don't think it is a pulley because if i apply water to the belt, it goes away for a brief period of time. I think it is alignment but do not see any alignment issues. Anyone trouble shoot this before?

2) When i get back to the boat lift with the engine running, I see a slight oil slick coming from the outdrive. It appears to becoming from the exhaust... as droplets splash down from the exhaust, the oil sheen appears. It could be fuel or oil. Curious if anyone has this and has done any trouble shooting?

Thanks, Tim

[Xcomunic8d]

Belt dressing works wonders but it doesn’t fix the root problem.

Start here:
https://www.youtube.com/watch?v=AEUe6uKxTv8

Pray it’s not a pulley alignment issue. It happens but can be a pain to fix.
I’ve not worked on a merc 350 but I’ve worked on all kinds of auto engines gas and diesel.

Sorry I can’t help on the other issue but just look for leaks. There’s typical a trail to follow. If it’s based off Chevy 350’s they are notorious for rear main seals going bad.

[Capt Terry]

Originally Posted by MDseacraft

I have two issues I am chasing down:

1) I have a belt chirp. Belt looks to be in great shape - no sign of rubbing. Chirp increased with rpms. Not chirp when the belt is off. don't think it is a pulley because if i apply water to the belt, it goes away for a brief period of time. I think it is alignment but do not see any alignment issues. Anyone trouble shoot this before?Thanks, Tim

In my almost 60 years of boating I have always had outboards. However, being a Chevy fan for years including 35 years of Corvettes which included being an owner/mechanic on a ’68 Vette for 30 years, I have a couple stories that might help on the belt chirping.

Long story short the ’68 would throw the water pump belt at about 5000 rpm. During a comprehensive engine rebuild I learned there were two water pumps that to the eye looked exactly the same. However the correct one was maybe 3/16” different in length to the pulley-to-pump interface than the local after-market one I had purchased. With the correct water pump in place there was no more belt throwing when really winding it out.

Later on I had a good connection with the local Chevy parts manager. When I complained about what I thought was power steering pump squeal on my Astro V-6 when the engine was cold (even with belt dressing), he told me to replace the serpentine belt. I told him I usually buy from you, but you were closed on Saturday, so I bought one from NAPA last week. My parts manager said put on a GM belt. I did and my squeal was instantly gone!
Best wishes- problems can be elusive

[MDseacraft]

Thanks for the tips. I got a new belt today... Different brand from Daycon and the chirp is gone. So much better. Also think the oil sheen was the piston hydraulic fluid leaking out of the trim piston. Tightened the connection and hoping it is all better.

[Capt Terry]

Originally Posted by MDseacraft

Thanks for the tips. I got a new belt today... Different brand from Daycon and the chirp is gone. So much better. Also think the oil sheen was the piston hydraulic fluid leaking out of the trim piston. Tightened the connection and hoping it is all better.

Glad you solved your belt chirp. I try to solve problems with the least expensive and easy trials first; learned the hard way.