Serpentine Belt Shredded

[dpickett]

I have a 2001 21V with 350 Mag MPI engine. Engine serial # 0L671100. It is not a part of the recall on pulley alignment: http://www.mercruiserparts.com/bulle...2003/EN_04.PDF. Are there other similar recalls that people know of?

Back in October, my serpentine belt popped off and caused my engine to overheat. Luckily, no major damage. At the time, I couldn't find anyting wrong with the pulleys, so I just replaced the belt. I also replaced the impeller. There was belt dust in the engine compartment. I only used the boat for 3 more hours (with no issues) and then stored it.

Upon putting it in the water for the first time last weekend, the belt came off and one rib snapped. Lots more belt dust. I checked all the pulleys again and noticed a few things. There is a fair amount of rust (I'm using my boat in brackish water) on all of them, especially the water pump pulley. Also, the water pump pullley wobbles a little bit. I took a video of it. It's here: https://photos.app.goo.gl/BPvVM8etzwUszXaU9

I have scoured all the pulleys with a wire brush and scraped out a bit of rubber from some of the groves. Also, the pulleys all spin fine (excepting the crankshaft pulley which doesn't spin and the raw water pump pulley which requires from force to spin in).

I took off the water pump and pulley and am considering replacing them. Questions:
- Could that amount of wobble cause the belt to come off and shred?
- Could the rust cause the problem?
- Anything else I should check?

I have a new belt ready to go one once I replace the water pump and pulley. Also, I now have a laser alignment tool and kriket belt tension gauge that I plan to use. I attached a before and after pic of one of pulleys I cleaned and pictures of the broken belt.

[dpickett]

I've had issues with the bilge pump not getting the water out also. I just moved it and got a lower profile one this winter. I ended up moving to nearly underneath the drive shaft. It's a bit off to the side because there wasn't enough clearance right under it. That seemed to be the lowest point where the water goes. We'll see if it does any better there. I'd also like to get a 3 way switch, so I can leave it in automatic mode. Did you come up with a solution for the bilge pump?

So, did the water on the belt cause it to slip? come off? break? I have no doubt my belt got some salt water on it in the fall, but it was dry last weekend. I never got the boat about 5 mph before the belt shredded and came off. Maybe the salt water made it weak over the winter?

Not sure why the video didn't work. My dad had a similar problem on an iPad, but it worked on a computer.

[chpthril]

Even a little play in the circ pump can be an issue. Definitely replace it.

[dithanbyy]

thank you for sharing and wish you a happy existence
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[chopper515]

dpickett, I have same boat. I had similar issues with pulleys squealing and alternator rusting. You'd be surprised how much water can get between the engine cover and the hull at the stern especially if you have kids using the sun deck as a diving board. It's a bad design. I installed a gutter system to route the water away from the belt. Now that I'm reading Gumby's post, I really need to check on the vent issue as well.
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[dpickett]

Chopper, did you cut that gutter piece and make the mouting tabs? I'd like to do that. I think I'm getting water dripping off the engine cover that's going onto the belt. I also want to figure out how to keep water from coming into the vent when I stop. Not sure how much it's safe to block that vent in order to keep out water.

[dpickett]

Make sense.

I took a hose and poured water into the vent from the outside this morning, and there was only a trickle of water that came out of the box. The bottom of my box has a tube running down to the bottom of the bilge, and I only got a tiny amount of water coming through it. Not sure how or why, but I guess that isn't an issue.

I also sprayed some water on the top of the engine cover, and I got quite a bit of water that ran down the back of the cover, then along the underside before dropping down on the engine, on the belt and lots of other places. Not good since I'm in salt water. Working on figuring out how to block that. I'm thinking about trying to use some cloth/vinyl material to attach between the engine cover and transom of the boat. Not really sure yet how to do it.