Spun prop or worse?

falconer

Recruit
Joined
Jul 12, 2004
Messages
4
I'm looking for possibles. I have an 1986 26'loa 10' beam 350 w/ Mercriuser alpha outdrive. A month ago at launch it ran at 20 mph at 3000 rpm; now I get 15mph at 3200 under the same load. Is this the beginning of a spun prop or is there some coupler problem that I'm not aware of due to the boat's age? Any thoughts on the possibilities before I call the mechanic will be appreciated.
 

motox6

Petty Officer 3rd Class
Joined
Apr 4, 2004
Messages
85
Re: Spun prop or worse?

Is your outdrive trimmed right? Is the out drive creeping down?
 

crazy charlie

Vice Admiral
Joined
May 22, 2003
Messages
5,604
Re: Spun prop or worse?

Usually after a boat is in the water for about a month.There are things happen that can slow the boat.First is any growth or barnicles on the bottom and drive and trimtabs.This is the easiest thing to check.Then what always follows is the constant bringing of supplies and gear aboard that stay on the boat adding weight as the season goes on.The water tank is usually another way that weight is added.holding tanks as well and if there is more fuel on board now than when it was launched.When you add all this extra weight up and take the extra drag of a dirty bottom into account,it can slow you considerably.A spun prop will usually make it sound like you are overrevving and is easy to notice.Make sure your trimtabs are not stuck down,this would also slow you down.Check these things out before calling the mechanic.Post back what you find Charlie
 

Trent

Captain
Joined
Nov 17, 2001
Messages
3,333
Re: Spun prop or worse?

Make a mark across the prop hub and go try it. If the mark moves its a spun hub. A spun coupler will cause your engine water temp. to go up.
 

falconer

Recruit
Joined
Jul 12, 2004
Messages
4
Re: Spun prop or worse?

Thanks. I did find a crack in the outdrive reservoir at the brass fitting on the bottom resulting in a slow drip on the transom. The bottle is about an inch low since the beginning of June. I don't know if thats allowing the trim to change, but it is now 1st priority. It appears to be Prestolite, or similar, and is marked w/ the Mercruiser logo. Any idea where I can get one mailorder? Are there any tricks to replacing it?
 
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