serpentine belt blew after 10 hrs

[c-caron]

Has anyone replaced their belt with an automotive type? I put in a Goodyear brand. Seemed to fit fine and tight but it blew up after about 10 hrs. The Mercruiser OEM part is $70. Is there something special about the Mercruiser belt that makes an automotive part not work? If not, I'll have to check my pulleys more closely.

[hoopykat]

I would think the Mercruiser belts are reinforced more because they are subjected to higher RPMs for a longer time period, since automotive belts get sort of a reprieve as engine speed slows with higher transmission gears. Marine engines don't have that luxury, and when we're at WOT, the engines can be revving 2-3 times faster than an auto engine. I wouldn't chance using an auto belt on a marine engine. Plus the damage that can be caused when the belt lets loose and components suddenly spin to a stop.

Mike

[walkers2rad]

While you have the belt off so to speak you might want to check to see that all of the things it spins still spin like they should, especially the raw water pump. I have had the vanes flip over backwards which caused all sorts of problems with belt slipping at high rpm's and overheating.
Ray

[chpthril]

Belt is a belt is a belt. There are about 4 co's (Gates, Dayco, Good Year, Continental) making 99% of all the belts out there.

check for pulley alignment

Check for play in any of the pulleys caused by a bad bearing or loose nut/bolt

Check to see if all the pulleys will spin free. No noise or jerky motion.

inspect the pulley grooves for damage.

if the engine has a spring loaded tensioner, check that it will load and unload looking to make sure the spring is not broke/binding.

Double and tripple check the belt size

[spharis]

Yep, you've got something besides the belt going on there.

[Keith22v]

c-caron, same thing just happened to me this past weds.
Same belt (goodyear)with almost no hours too.
I bought a Mercruiser belt today and am going to check pulley alignment tomorrow. How would alignment change though? hmmm
My 2003 22v had a TSB about shredding belts.

[dogbert]

I just had to replace my alternator and pulleys. They were whining alike a loud sewing machine and my alternator stopped charging. Robbed the engine of a lot of horsepower.

Water splashing around in the bilge and kicked up by the belt could be a cause.

[c-caron]

Some of you said I need a marine reinforced belt. Some said I just have to check everything else. So I'll try an automotive Goodyear one more time. Tightened it up just enough so it doesn't slip and I have about 1/4" play between the top 2 pulleys. Also cleaned the pulleys and applied belt dressing. I'll watch the belt for a while and keep a lookout for wear.

[Paublo]

I don't know if it applies to your boat but Merc had some problems with belt alignment and I think the tensioner pulley.

[R&T Babich]

The belt on our boat was the original (7yrs) so I replaced it with an auto belt and carried the old one as a spare. Put 30+ hours on it and it started squeeking last trip. There was also a fine powder of rubber all over. The original Merc belt is .81 inches wide and the auto belt is now .825, but was probably wider. The Merc belt is a little thicker, too. The idler pulleys and alt pulley fit fine, but the raw water pump pulley seems to be the one that is grinding off the edges of the belt - that's where most of the rubber piled up. I'll try the original Merc belt next week to see if the noise goes away.

[Domsz06]

belts are belts, sometimes, like everything else you may have a bad one, why I always carry a spare. like 15 bucks at autozone, if your blowing through belts you have an issue, if you put a new one on and it's fine looks like you just had a bad one.

[R&T Babich]

c-caron - How's the belt holding up?

The aftermarket belt I tried was a Drive Rite and it appears to have not been made correctly. The ribs on the belt are too narrow and allowed the belt to sit further down in the pulleys, thus grinding the edges off. I found a Prestone belt, 880K6 ($14), that fits much better and looks very similar to the original Merc belt. I've put 12 hours on it without a problem.

[c-caron]

i replaced with the same goodyear that blew. had some trouble getting the right tension on it... sometimes belt wouldn't catch. but after keeping an eye on it closesly, seems to be fine. no frayed edges and no belt on the engine.

[R&T Babich]

c-caron, same thing just happened to me this past weds.
Same belt (goodyear)with almost no hours too.
I bought a Mercruiser belt today and am going to check pulley alignment tomorrow. How would alignment change though? hmmm

Our new Prestone belt was thrown off yesterday after 14 hrs with no noises, except for the temp alarm. The outer rib was half stripped off with pieces hanging. The picture shows one way the pulley alignment can change. I had replaced the impeller at the beginning of the season. Guess I didn't get all the bolts tightened properly which is strange because I usually triple check every bolt. The loose upper bolt allowed the pump to wobble about 1/4".

At first I thought it was a flipped vane in the raw water pump. I have a spare pump that is a brand new take-off, same part no., everything looks identical. When you look in the ports the vane is oriented the opposite direction of the one on my engine. From the direction of belt rotation my pump is spinning correctly. I don't know why the new one is backwards.

[walkers2rad]

I think the vanes get flipped backwards if the engine diesels backwards a couple of revolutions after it is shut off. Having the idle speed too high or shutting the ignition off before the engine is fully wound down can play a part. It only takes a little bit just one time and it may not even be noticable. Internal issues like carbon build up or a leaky fuel injector(s) can contribute so it might be worth it to try some top cylinder cleaner and/or fuel injector cleaner if that is the case.
I also think the urathane globe impeller is so much more pliable that I give it a much better chance of survival if this happens. It will also outlast the others several times over and in my opinion is well worth it. If you use the black impellers and let your boat sit for months with out turning it over (off season) they take a set in the area that it is squished down and those two vanes crack. This is why you need to change it at the beginning of the season! Not only is the globe a better material but you can crank the engine over every once in a while to move it around. If the engine happens to start it is no big deal because it can run dry without damage, just shut if off right away.
Just my two cents!
Ray