engine slips at high rpm; clicking sound 25hp 1987

[yahoox]

Hi all. Just bought a 1987 mercury 25hp 2 stroke. Its the type that engages in gear by turning the throttle. It idles fine, puts at low rpms fine, but winds out of gear at higher rpms. <br /><br />In the garage, I put it in reverse and turned the prop. It definitely turned the innards. I then put it in forward and turned the prop. It made a clicking sound???<br /><br />Any ideas? TIA

 

[Rob Isaacs]

Re: engine slips at high rpm; clicking sound 25hp 1987

Sounds like a spun propeller hub. These can be replaced for little cost. Remove Propeller and put a mark on the brass inner (splined part) then mark in alighn part of the outter (Propeller housing. Test the motor again. after you hear it slip a few times remove the prop and check the markings to see if they have moved. If so the hub is deffinatly the problem. Regarding the cliking noise try turninning the prop the other way (not to far. dont keep turning) It souldn,t rachet both way. This is normal the gears are desighned this way

 

[yahoox]

Re: engine slips at high rpm; clicking sound 25hp 1987

Thanks Ozzie Bob! The shaft is splined. Am I to understand that the prop is a two piece unit? (a hub pressed into the finned portion?) Thanks again.

 

[andy6374]

Re: engine slips at high rpm; clicking sound 25hp 1987

Originally posted by ateweight:<br /> Am I to understand that the prop is a two piece unit? (a hub pressed into the finned portion?) Thanks again.

You got it. This is a failsafe in case you hit a submerged object for instance. Instead of creaming your propshaft/gears/etc. you get a spun prop hub.

 

[Texasmark]

Re: engine slips at high rpm; clicking sound 25hp 1987

One of the things that sold me on mercs early on was the !@#$%^&*()_+ shear pins on OMC....and Scott Atwater.<br /><br />Just about the time you got positioned on the winward side of rip rap with the big waves and all, where you just knew the fish were ready to tear up whatever you chunked at them, you'd hit something and bam goes the shear pin.......before the days of trolling motors. So it's over the side to save your dingy form the spoils of the waves.<br />-----------------------<br />Forgive me Andy, but I have a different idea. Hopefully one of us gets the problem corrected.<br />-----------------------<br /><br />But the clicking sound gets me. If the hub is spun, you have rubber on aluminum (or brass or SS) and that should squeak if anything. And if it spins, it should spin or attempt to spin in both directions.....and I never spun a hub and on a 25 you would really have to whack something. I would think the prop would be trashed out.<br /><br />I had an I/O (140 Mercruiser) that clicked and it was a shift linkage problem. The drop pawl in the "foot" that switches from forward to rev (slides back and forth on the prop shaft) only has a short distance to travel but must engage both directions with vigor. If your linkage is amis, you could be over engaging one direction (rev in your case) and barely engaging in the other (fwd) so when you put pressure on it it skips (hops outta gear).<br /><br />Before you chase the prop, I'd disconnect the shift linkage from the twist grip and manually put it as far as it will go in rev and then in fwd and see if the problem goes away. Then it's a matter of tweaking the linkage so that it moves the shift lever as far as you did manually and your done.<br /><br />HTH,<br /><br />Mark

 

[yahoox]

Re: engine slips at high rpm; clicking sound 25hp 1987

Yup, the prop was gorfed when we bought it (three of us bought the boat to keep at the company beach house.) I had it repaired and my business partner promptly gorfed it on the rocks in Netarts bay the next week. I have a new prop coming already and perhaps this will solve our woes.<br /><br />But I'm not so sure. While the prop was being repaired, the shop gave us a loaner. It wasn't the same prop, but it fit. We seemed to have the same problem. If the new prop doesn't solve the problem, I’ll try Texasmark’s advice. I’ve already examined the linkage, and it appears not to have any unusual wear, but it should be an easy enough test to pull the linkage and put it in gear manually. <br /><br />Thanks for all the great advice; I’ll report back.