How to Check Pulley Alignment

[jdoe71]

How does one check to ensure the drive pulleys on the front of the engine are aligned correctly? Eyeball test says they are and there is no sign of the alternator mounts being bent or weak and flexing but I want to be sure.

Our boat had a Dayco top cog drive belt on it that looked a little worn. So last month I put a new Gates Premium XL belt on it, having read that a cogged belt dissipates heat better. Yesterday while motoring across the bay to our winter storage, this belt with only 30 hours on it blew itself apart, which caused an anxious moment while my brain tried to decipher why the tach would suddenly quit but the batteries still had full voltage showing. The temp gauge needle skyrocketing up quickly gave the answer within 20 seconds or so. Anchor down, put the spare on and carry on.

This belt was properly tensioned, I check it daily along with oil levels and a general visual of the engine. It looks to me like there was a void in the inner belting material but there is a lot of material missing, it blew individual cogs all over the engine room. The outer casing of the belt is intact and there are no nicks or marks that might indicate it hit something so I really feel the belt was defective but that has to be really rare. Or not?

When this belt was installed, it left rubber dust all over the place for the first hour or two, then after re-tensioning it settled down and did not do that anymore. I wipe the oil filter down as that's the easiest place to see whether it is shedding dust or not and it was not after that initial hour or two. Was motoring at 2200 rpm and had just increased revs to 2500 when it blew, we have run it as high as 2700 with that belt on there and no issues. The batteries were fully charged, having been on the float cycle of the charger, so there was little load on the belt, just the water pumps.

Because the P/O had left other belts on board that looked pretty thin, I am wanting to make sure the pulleys are aligned. There is a fair amount of rubber dust on the front of the engine and bulkhead beside the belt. Engine has 480 hours on it. Does any of this sound like pulley alignment might be a problem?

And as a side issue, does anyone have any comments on choice of belt? This is a Universal M3-20, stock 51 amp alternator and stock everything else. The Dayco Top Cog is supposed to be good but it's odd because the cogs are on the top not the bottom which is why I went to the Gates cogged belt. Comments? Thoughts?