Merc 50 water problems. Impeller?

[Hcivic88]

Hi there
I have a 50HP Mercury outboard, I believe its an 85-86, its what they call a "brownband". So my problem is, when I'm driving at a decent throttle everything works fine, but at slow or at trolling speeds, the motor doesn't seem to be spitting any water out. As I slow down it'll work for a bit, but then the stream will slow down, and it'll eventually turn into little spits of water coming out, then eventually that will even stop and it will only be almost a steam coming out of it.
So does anyone have any ideas of what may be causing this? I only bought the boat maybe a month ago, so I'm not too sure on its history. I was thinking maybe impeller? although it works fine when your giving it throttle so I'm not sure.
Thank you very much
Jamie

 

[stnb4ever]

Re: Merc 50 water problems. Impeller?

Sounds like your impeller. If these boats sit up for a while or if the boat engine is started without an adequite amout of water to the impeller the impeller will lose its form and function impropperly or in some cases not at all. They say it only yakes 5 seconds of running without water to destroy the impeller. If it were me I would replace the impeller just to be on the safe side. It is a lot cheaper to replace the impeller then it is to replace the engine. It will also give you a little peice of mind. Hope this helps.

 

[Hcivic88]

Re: Merc 50 water problems. Impeller?

oh wow, I didn't realize they could damage that easily, looks like I may be changing out the impeller then.
thanks a lot for the help, I greatly appreciate it
is this is a big job to change? something I can do by myself or would I be better off bringing it in to get done? I've done a lot of work on cars so i have some basic knowledge, never worked on an outboard before though

 

[nickandm]

Re: Merc 50 water problems. Impeller?

I just replaced mine. It wasn't to hard, however, my outboard is much smaller than yours. If you go to this website:http://www.mercurypartsexpress.com/PartsExpress/ProductSelection/ServiceParts/sphome.asp?CID= you can find a diagram of your motor that should be helpful.

 

[GreatRiverDucker]

Re: Merc 50 water problems. Impeller?

Usually a waterpump is fairly simple to replace. You should get a manual, it helped me a ton my first time. You can order a kit for the whole pump here at iboats. Good Luck!