78 johnson 140 locked up

[fastgtfairlane]

my name is mark and i live in wilmington nc. im new to this forum. anyhow back on track, i have a 1970 sidewinder 15ft fast v hull boat with a 1978 johnson 140 outboard on it. yesterday 3 of my friends and i went crusing around. while out about half the day later cruising around the engine died. it acted like it had a dead battery but i couldnt turn the flywheel over at all. i remove 3 plugs while on the water and it didnt make any difference. i would love to avoid a costly rebuild. is there anything i can do to try and free it up. i was thinking about marval mystery oil but will not try it until i have some reassurance. please give me some suggestions. thankyou.

 

[Reggie08]

Re: 78 johnson 140 locked up

Drop the lower unit then try to turn the flywheel. If the flywheel turns, your lower unit locked up. If it still doesn't turn, then your powerhead locked up.

 

[CharlieB]

Re: 78 johnson 140 locked up

Check the spark plugs, do any of them have a silvery coating?

If so you toasted a piston and are in need of a rebuild.

I'm hoping that it turns once you drop the gearcase.

 

[fastgtfairlane]

Re: 78 johnson 140 locked up

i removed three of the plugs. i will stop and get an actual plug socket today to check the last one. the other plugs looked normal. how difficult is it to drop the lower unit? im pretty mechanically inclined and have most of the tools i feel i would need. ive never really messed with outboard engines before. im pretty sure i can handle this but does anyone have any suggestions on dropping the lower unit.

 

[emdsapmgr]

Re: 78 johnson 140 locked up

I'd contact Ken Cook Co, in Milwaukee and get an OEM service manual for it. There should be 5 bolts to drop the lower. Don't forget the one under the trim tab fin. You'll need to disconnect the shift rod under the bottom carb.

 

[fastgtfairlane]

Re: 78 johnson 140 locked up

that sounds easy enough. how far down are the bolts that i need to remove. also will i need to disconnect the driveshaft.

 

[iwombat]

Re: 78 johnson 140 locked up

I think that's 6 bolts and one bolt to get to the 6th.

4 on the sides, one in the back and one under the trim tab.

 

[rdnk_4_lf]

Re: 78 johnson 140 locked up

if you need a lower unit i have 1 that fits a johnson 125 4 cylinder

 

[fastgtfairlane]

Re: 78 johnson 140 locked up

i will try and get it apart maybe this weekend. if it is in fact the lower unit, how much do u want for it. does the lower unit have all of the gears in it. also the prop turns freely when not in gear. not sure if that has anything to do with anything or not. its a 78 140 v4

 

[Devdog99]

Re: 78 johnson 140 locked up

I had the same thing happen to my Suzuki 140. The lower unit locked up on it. When it happened, the whole motor came to a very abrupt hault. I couldn't even move the flywheel a 1/4 turn and I couldn't get it out of gear. Unfortinently the bolts holding on the lower unit were so corroded that I couldn't get it off and had to get a new engine. I hope you have better luck than me.

 

[fastgtfairlane]

Re: 78 johnson 140 locked up

mine came to an abrupt hault also. the flywheel will not move either. mine will go in and out of gear. i dont think mine is corroded though. i havent really had a chance to look into it yet.

 

[fastgtfairlane]

Re: 78 johnson 140 locked up

im guessing mine is the lower unit. ive had the boat for 2 1/2 years and havent changed the oil in the lower unit since ive had it. i found out after the fact that it should be changed every year.

 

[fastgtfairlane]

Re: 78 johnson 140 locked up

last night i tried to pull the lower unit off. i got the 2 bolts on each side and the 1 big one underneath. i couldnt get the lower unit off. do i need to take the trim tab off also? what else do i need to do?

 

[iwombat]

Re: 78 johnson 140 locked up

ahem . . .


"I think that's 6 bolts and one bolt to get to the 6th.

4 on the sides, one in the back and one under the trim tab."