25 hp Evinrude clunking at high speed

Hi there,<br /> I have a small problem with my 25 hp Evinrude outboard ( model 2540ZM ). It has developed a rather harsh clunk at high speeds only, the first time it happened I thought I had hit a log or something. I have read through similar topics in the forums that indicate a worn Dog clutch however there a few things that dont make sense. The fault only occurs at high rpm in a plane, when it is under full load pushing into a plane the fault does not occur. I have also noticed that if I hold presure on the gear selector lever , in the forward position , the fault does not occur at all. Is it an indication of a worn dog? Or is there some kind of selector asembly adjustment or repair that may fix the problem. <br />Thanx for your help.

Re: 25 hp Evinrude clunking at high speed

You have a timing problem: Time for a new clutch dog - Sorry, couldn't resist <br /><br />There is no adjustment to the shift linkage on the 25 hp models, it's just an upper and lower shift rod, connected by a link. I've seen them do exactly as you describe, it'll only get worse, eventually jumping under the slightest load. Good news is replacement parts are generally available.<br /><br />-John

Re: 25 hp Evinrude clunking at high speed

Check the forward gear carefully, too. If the edges that engage the ears of the dog clutch are rounded, you need to replace the gear, too. If you just replace the clutch, it'll eventually do it again.<br /><br />And every time it jumps out of gear, more damage is done. So, it's adviseable to not run it until the problem is repaired.<br /><br />HTH........ed

Re: 25 hp Evinrude clunking at high speed

Yeah...new dog should do the trick. Or if ya' know a good machinist, the lobes can be milled square again. But the have to be perfect. What ya' take off one lobe, comes off the other. Look at the forward gear also and check the shape of it's lobes. Ususally best to fix or replace both.<br /><br />Timing problem????? That was bad John....really bad....

Re: 25 hp Evinrude clunking at high speed

Dang Ed you type quick!!

Re: 25 hp Evinrude clunking at high speed

Thanx for your advice guys, I guess I had better break out the spanners and pull the bottom half of the leg apart. Damn, no fishing this weekend, oh well. Ill keep you posted on what I find.

Re: 25 hp Evinrude clunking at high speed

hahaahahaha<br /> o my gawd<br /> timing<br /> hahahaah I gotta remember that one. will be useful someday. awww I am still giigling. what break out the spanners???<br /> mmmm nah break out the Fosters then the spanners. <br /> I dunno about fosters but over here bush cant navigate and bud caint fix anything.<br /> may as well do a seal kit and a water pump job while your in there. <br /> good luck and keep posting

Re: 25 hp Evinrude clunking at high speed

You guys were right. The dog clutch was the problem! I got hold of a re-conditioned gear set and clutch dog, Installed the parts and took it for a test run. Hey Presto, problem fixed. The whole operation cost $160. $150 exchange for the gear set,$10 for a new shear pin and water pump grommet.<br />Thanx heaps for the assistance.