Freezing up!!!

retired teacher

Recruit
Joined
Dec 1, 2008
Messages
5
I'm having a problem with my 25 hp Mercury freezing up when temperatures reach down in the 20s. I'm a duck hunter and when we arrive at the boat launch with these cold temps I cannot shift into either forward or reverse. I've got a water problem somewhere in the lower unit, I think. The gear case oil looks fine. Is it something to do with the impeller? Anyone with ideas??
 

cwglo1

Recruit
Joined
Dec 16, 2007
Messages
3
Re: Freezing up!!!

Hi,
there are several linkages which would be worth checking to see whether they are sticking on you. My thinking is that the problem is there at all temps, but evident at low temps.

there is the cable or linkages from the controls or the side which rotate the shift shaft, make sure they arent worn. there are crappy plastic bushes which the shift shaft rotates in down the central pivot these can somethimes play up, but they are a prick to get to.

then there is the reverse lock cam, this can be problematic when worn in older motors. this pushes a rod upwards to engage the claw on the transom mount. make sure that the transom linkages arent frozen also.

then there is the gearbox, which is a tricky one if you get this far. there can be a worn selector cam, faulty return spring, grit in the guide of the pin, or the dog selector itself doesnt move freely on the prop shaft. to get into the guts of the gearbox you need to pull the prop of and then the hub where the exhaust comes out, there should be some threads on this if you get this far..

This all can be done in a shed with only a slight knowlege of a motor.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Freezing up!!!

Of course it is also possible that you have water inside the shift cable, freezing and locking the shift cable.

When if 'freezes' again, disconnect the shift cable from the linkage at the engine and see if you can shift the motor by moving the linkage by hand, if so, replace the cable.
 

retired teacher

Recruit
Joined
Dec 1, 2008
Messages
5
Re: Freezing up!!!

Water in the shift cable is what I've been thinking is the problem. This is a tiller model. I don't see how it could have gotten in but anything is possile when it comes to outboards. i've talked to mechanics and they are puzzled. All linkage looks good and the lower unit checked out good as well. No sign of water in the lower gear case. Looks like I'm down to the shift cable. Probably will replace it, if I can figure out how it's done.
 
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