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496 Mag Serpentine Belt debris

Old 03-01-2012, 06:23 AM
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Default 496 Mag Serpentine Belt debris

Need some guidance on my Cobalt. Powered by twin 496 Mags, Both motors exhibit alot of belt debris. Really fine shavings.....I have sighted the belts and they look straight, wondering if this is a sign of a failing component? Replaced both belts last year and checked tensions. Anyone else have this issue?

Thanks!

Eric
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Old 03-01-2012, 07:01 AM
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It's been many years since I sold my Baja with a 496, but I remember vividly that there was always a great deal of nasty black "belt soot" all over the front of my engine room. They all do that and it's quite normal.
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Old 03-01-2012, 07:14 AM
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I think it's pretty normal to have some. I guess it depends on what you consider a "great deal".
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Old 03-01-2012, 08:20 AM
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Yes, my twin 496s get nasty black dust on them as well. Just keep an eye on the belts.
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Old 03-01-2012, 08:22 AM
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Wow ...I was hoping it was a curable item. Anytime I go into the bilge I track black streaks across my seats on my way out....Any thoughts on how to solve this issue?
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Old 03-01-2012, 10:21 AM
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They all do it and some boats are worse than others as the proximity to bulkhead or flat surface makes a difference.

I have the same issue with black streaks everywhere. Just keep a clean rag in the boat wipe good before you step in and around. It comes off pretty easily.

The only answer I have been able to come up with that makes some sense is the mere fact that belt system is a mess. It's compact and very nice closed cooling setup but the belt has a lot of load on it everywhere. It really needed an extra groove or two.

Ever notice how much belt coverage there is on all the pulleys? It's about 80% or more belt contact on everything. They knew that it was at its limit in my opinion.

I put a slightly bigger pulley on my alternator to show it down a little.

Also, most all of the components are moving at crank speed which is crazy to me.
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Old 03-01-2012, 10:52 AM
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Lots of 496's we see that have a lot of belt debris are generally the ones with a moderate amount of rust on the steel pulleys. If your pulleys are rusting the rough rust pits and such act as sandpaper on the belt. remove the belt and wire brush and clean up the pulleys and put a coat of gloss black acrylic appliance paint on the belt grooves and give that a try. Try to keep excess amounts of water, especially salt water, out of your bilges. STOP THE LEAKS! Engines are not supposed to rust. They rust mostly from to much water sloshing around in the bilge.
If this is whats happening to your engines, hope this helps.

Best Regards,
Ray @ Raylar
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Old 03-01-2012, 11:05 AM
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anyone with al. pulleys w/ experience? I know my pulleys have some rust on them. I'll have to take a look at coating them..As for water in the bilge....I've never been on a boat that didn't hold some water...Since I bought it, my coalt holds about an inch....I may have to be more dilligent with my water removal techniques this year...
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Old 03-01-2012, 11:35 AM
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I am seeing this also and never liked it. In my opinion, SDfever is correct and the belt is undersized (in width) and a small amount of slippage is occuring. My pulleys are not rusted but neither am I seeing a lot of material all over the engine bay, but a good amount on the firewall (bulkhead) in front of the engine. The firewall is very close to the front of the engine on this boat which may keep the debris confined to that area.

Looking at the part numbers, the newer automatic tensioner is about a $100 retrofit. It is just a bracket and the tensioner and a pulley. Does anyone have any experience that the auto tensioner makes any difference (good or bad)?

I am also installing a new Dayco belt. They have developed a new belt that has a small (very small) groove in the rib of the belt that is supposed to improve pulley grip and increase the pulley alignment tolerance. This should decrease wear and noise. I will let you guys know if it makes any difference or not.

Dan
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Old 03-01-2012, 12:05 PM
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The debris is only on the front of my engines, but make a heck of a mess. Its tough to clean off too. The debris is so fine - and its basically melted rubber, so it smooshes around when touched. Was the new idler setup developed to increase belt tension? For a 100 bucks if it would stop this issue I'm game! I actually have a spare belt with me as a just in case - because I thought it was specific to my motors -

What is the belt you are referring to? Diff material/configuration than factory belt?
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