4.3 merc making noises from the outdrive at High idle

Hello There,
This is my first time on this site and hopefully someone can offer me some advice on my troubles!!
I have a 1991 4.3 merc with alpha one outdrive.I use it in salt water but flushed after every use.I notice after a day of running today in salt water,when i brought it home and ran it on the muffs, i noticed when brought up on rpms (not in gear)i could hear a rattling noise coming out from what appears to be the outdrive.It does not make the noise at idle only when i bring up the rpm,s.also the outdrive was tilted up. I have never heard this noise before, although i don,t ever recall raising the rpm,s on the muffs before. But tonight i was in a bit of a rush and wanted to flush it quickly. Also i don,t know if this as anything to do with the problem, but when i am in the water and go to reverse the engine stalls.
If someone could help with my troubles it would be greatly appreciated.
Thanks
Roy

Re: 4.3 merc making noises from the outdrive at High idle

The engine stalling in reverse is probably a issue that can be fixed by adjusting the sift cables.

The noise could be anything, the first thing that we need to know is what kind of noise, grinding, knocking, humming, growl or what. The kind of noise can tell us what it is. example if it's a knocking, your u joint could be tapping the housing if the drive was all the way up. If it's a grinding it could be the gears in the upper unit. If it's humming it could be a the water pump in the drive, the muffs don't supply a good enough water flow to run it at a high rpm only idle. If its a growl it could be your gimble bearing....and so on and so on.

Welcome to iboats, you can learn a lot hear! Just supply as much info as you can, there is no such thing as to much info.