Johnson 175 Lower unit problem

[acsamples79]

whats up guys, i recently bought a 1977 viking deckboat with a 77 johnson 175hp outboard on it, everything on the motor is tip top and was well taken care of, but the lower unit has a problem.. basically with no prop on it, if you grab the top drive shaft ( going into the upper part of the motor) and turn it, then the bottom prop shaft will turn like its supposed to... BUT if you put even a slight amount of weight on the prop shaft like by grabbing with your hand or definetely with a prop on it, it wont spin any more

so im wondering are the gears stripped out on the inside? like i said it spins like its supposed to unless you grab the prop shaft, then if you twist the upper drive shaft nothing happens with the prop shaft.... so im confused what he problem is

any ideas will be greatly appreciated

 

[5150abf]

Re: Johnson 175 Lower unit problem

Does it do this in forward and reverse?

Drain your oil, if you blew a gear there will be alot of metal shavings in the oil.

The way those work is, there are 3 gears,forward, reverse on the prop shaft and a pinion gear on the drive shaft, these are always in contact and spinning if the engine is running.

There is a clutch dog that slides either forward or back when you move the shifter to engage the gears.

If the prop shaft is turning at all I would think it is a problem wiht the clutch dog.

First thing is to drain the oil, it will tell you the story prett quickly, post results.

 

[acsamples79]

Re: Johnson 175 Lower unit problem

it does do it in both forward and reverse.... unfortunately when i got the boat and motor the lower unit was already off and oiless... so i wont be able to tell that way... ill def. look into the clutch dog possiblity

the previous owner just said he THOUGHT the gear was stripped but he didnt really know.. i thought he was crazy when i grabbed it and it turned the prop shaft until i realized it only does that when theres no pressure on the prop shaft so ive been lookin at all possibilities..

i do have a johnson 115 full motor and all that works that was sold with the boat extra, but id much rather have the 175 on there

 

[ezeke]

Re: Johnson 175 Lower unit problem

The 1977 175 gearcase is hydraulically assisted, so it will not perform well unless filled with oil.