Broken Belt - Question

[skolbe]

My port motor, the belt started slipping after we were anchored out when I went to start up. I went down below and tightened the belt and made sure nothing was stuck. All seemed to be fine. Started idling out of our anchorage spot and all was fine. Went to get up on plane and heard clicking then like something fell. Bottom line the belt broke. Water pressure alarm went off and pulled back throttles and shut the boat down. Boat thermostat read higher but it happened so quick. No issues. Planning to replace the belt. All the pulleys seemed fine. I could turn the water pump manually. Anything else I should look for? How can you tell if a pulley is bad. Belt is nine years old. Or is it just a bad belt. I plan to replace the belt and see how that does. Boat is 350 MAG - V Drives.

 

[Lazy Daze]

Visually inspect the pulleys... rust/corrosion.
Put a straight edge on the pulley faces, from one to another... make sure they are flush with each other.
Spin the pulleys by hand - both fast and just "back and forth" - look, listen, feel for anything other than a smooth, rolling feeling with no grinding/bearing noise. A mechanic's stethoscope or a long handled screwdriver or even a dowel can help you hear better.

From what you said, I doubt any damage was done to anything. The first culprit would be the impeller but if you got to it as quick as you said, I doubt there's any damage there, either.

In most cases, you can cross-reference the belt at NAPA to a Gates or Dayco belt. Buy two of them - replace the stbd one and keep it onboard as a spare.

 

[skolbe]

Thanks great advice. I will buy two belts.

 

[Lazy Daze]

Come to think of it... I seem to remember getting pulleys at NAPA, as well, for my engine... Although it was a while ago and I may be mistaken. If you do replace any, keep the old ones as spares, too.

Good luck!

 

[scoflaw]

Take a good look at your water pump, that shaft/pulley can walk right out of the housing. That belt broke for a reason

 

[CliffA]

In most cases, you can cross-reference the belt at NAPA to a Gates or Dayco belt. Buy two of them - replace the stbd one and keep it onboard as a spare.

I recommend using Gates belts.....I put two new Dayco belts on my engines last year when I tuned the engines up....both belts were tensioned properly but they both slipped when the engines were running causing a 'chirping' sound....i put two new Gates belts on and no issues....

I would use a small wire brush to clean the groves of the pulleys......

cliff

 

[Lazy Daze]

I recommend using Gates belts

I know of plenty of people that have used Dayco with no issues. But, personally, I prefer the Gates, too.

 

[rondds]

How do you match up the Merc belt to get the right Gates? How do prices compare. I think my Merc belts are around $60.

 

[CliffA]

How do you match up the Merc belt to get the right Gates? How do prices compare. I think my Merc belts are around $60.

just take one of the belts with you to the auto parts store that sells Gates belts....they will be able to match it....the price of a Gates belt will be 1/3 to 1/2 of the Merc belt.....

cliff

 

[skolbe]

Take a good look at your water pump, that shaft/pulley can walk right out of the housing. That belt broke for a reason

How do you know if the shaft/pulley is backing out? Obviously pulling the pump apart. I was planning to change impellers in the spring. But if it needs to be done it needs to be done.

 

[rondds]

You'd see water drip onto the bilge floor. Or a fine aerosol of water spray as the unit spins.

 

[Lazy Daze]

just take one of the belts with you to the auto parts store that sells Gates belts....they will be able to match it....the price of a Gates belt will be 1/3 to 1/2 of the Merc belt.....

cliff

Yup - there's a number printed on the belt that they can use. If it's worn away, just look up the Merc number and take it with you.

 

[bbwhitejr]

Here is the part number off of my 2006 350 Mag and the Gates part number I replaced it with. Runs perfect.

865615Q03(Merc-2704mm long)(6 ridges/grooves)- K061066(Gates Multi groove)

Bennett

 

[rondds]

Of course, I just replaced both in the spring. I'll try to remember this tip next time around!

 

[skolbe]

Replaced the belt and all is good. I ended up splurging on the Mercruiser Belt. But I am planning to buy a backup belt for the future.