I picked up an old 1975 Johnson/Evinrude 25 HP tiller. It's an old garage find and my intent is to rebuild her and have a spare motor for my skiff. The little motor has issues (putting it lightly). But for now the flywheel is locked in place. I have sprayed the cylinders with fogging oil and let it sit for a week and still not able to turn the flywheel. My next step is to remove the flywheel and tear down the powerhead. Probably have to use a block of wood to pound out the pistons. Is there any other method or trick that I may be missing? I did pick up a factory service manual, but it's for a 1974. Not sure how much difference there is between the years, but it can't be much. Any suggestions would be greatly appreciated. I am not mechanically proficient and this will be my first attempt at rebuilding a motor of any kind. So keep that in mind with your replies please, Thanks. TR
tilt the motor up (or lay it on the floor spark plugs up) pour some diesel in the spark plug holes and let her sit you said this is a spare so youve go time so once a week go out there and rock the flywheel back and forth a few times and put a little more diesel in leave the plugs in there when your done fiddling with it just so nothing gets in there (bugs bolts your kids GIjoes arm etc.) do this once a week and in a few weeks itlls come undone youll problably need to rebore it though unless its just light surface rust in which case youll need new rings oh and one more thing - take off the lower unit - it sounds dumb but sometimes they lock up and give the appearance that the engine is locked up and you and i both know no amount of diesel in the cylinders is going to free up a lower unit ;D -youll never be able to unstick it if you tear it down just pull the lower and the plugs and soak patiently once you get her freed up let me know and ill walk you through tearing on of these down and rebuilding it
Thanks Levi. I really appreciate the input. I'll try your way for a while. It's my winter project, so I have time. In the event that it is needed, how much can you bore one of these motors? Fair warning, I am not famous for my patience. ;D
you should be able to go at least 0.20" overbore but for now lets hope a rehone and rering will get you where you wanna be dont get to rowdy trying to make it go just rock the flywheel two and fro a dozen or so times put a little more diesel in it and let it ride for the week and like brett said while you wait get a service manual ebay has em used for around 20 bux
The largest I have ever seen one of the 2.992" X 2.5" blocks bored out is .030" or 30 thousands of an inch. If you do one cylinder you should do both and buy a set of oversize rings. You can find a good block for that engine for about $200 on ebay. It would be far cheaper than rebuilding. Frank_S
