Idled out of the channel, got on plane and ran about 2-miles at 3000 rpm. pushed the throttles and starboard motor would not rev higher. stopped to check the engines and found the idler pulley bearing on the blower had desintigrated and thrown the belt. Never saw temps go up or any other signs. Replaced the bearing and seems to run fine.

Should I be concerned or check anything else?? How long can you run the motors at low rpm w/o a blower belt? Idled a couple minutes and ran below 3000 for a few more.

Thanks

I beleive you can run it for as long as you want with out the blower belt, but it only has about 1/3 the HP, ran one for several hours before just to get home, put new belt on and everything was fine.

Thanks. paranoid I guess. we idled in on one engine.

You generally don't have to worry much when you break a blower belt, just get her back on plane and run home real easy.

If you run your oil pump off your bottom pulley be sure you didn't damage your oil pump belt our pulley..

last Fall while running real hard our broken blower belt took out the oil pump belt,thus zero oil pressure and a snapped rod the following day..
We have since fabricated oil pump belt guards for this season.
Hope this helps!

Are you running 575sci power? I just seized a 256 blower (with 200 hrs on it) this past weekend. Popped the belt off and couldnt even get it on plane. Anyway, just a matter of time befor these tiny blower experience problem.

Ya need a bigger blower? I know someone that knows someone

This really depends on what really happen and what SC you have. With a roots locked up, rotor to case or rotor to rotor, you going to have almost no power because the engine can't get air through the SC. If it had a bypass system, well then it would at least feed through that. If the belt just falls off, then it should still make somewhat decent power, although nothing compared to before because the sc will still spin when the vacuum from the engine sucks the air through it.

Thanks

Dustin, I would love to whipple it...and it might just pay off in the long run...however gas is going to kill me this year. My insurance company also decided they did not want to cover cats anymore so my rates are doubling also.

I really lucked out on my blower situation on the 4th. After the blower seized, I idled back to the sandbar, (still in pretty good spirits from running sub hundred speeds with heavy load) wrote the day off and cracked a beer. As luck would have it a guy walked bye, started talking about my situation and he had a brand spankin new blue merc 256w sitting on the shelf in his garage. $1100 bucks later and 2hrs I was back in business.

Dustin, I also went down to a 3.5" pulley and a 126* thermistat. Am I pushing the limits of the fuel map? It was my understanding that higher manifold pressure would throw more fuel at it. I did a shut down plug check at 4000rpm and they looked on the lean side.

Wow, right place at the right time. Good to hear. The stock map does not add more fuel as the boost goes up, its the same as stock boost fuel so it does lean up when you change the pulley size. It's a good idea to have the ECM modified for just a touch more fuel at the higher boost. For whatever reason, mercury did not even extrapolate the map. No problem other than that. Normally, I touch the boost fuel table a touch and bump the rpm limit to 5600rpm.

Thanks,
Dustin

Thanks all for the replies. the blower was not locked up. Ran fine to 3000. I can get the boat on plane w/out going over that. Once I replaced the idler bearing all was good.

BTW they are 575sci with Whipple intercoolers. Ran 92.6 at 5300 the other day. Still have 300 rpm left.