1980 mercruiser 140 prop wont turn and engine overheats

[av8tor3sp]

Hello all,

I have a 1980 17' galaxie tri hull with a mercruiser 140 i/o I am not sure excatly which outdrive I have, it has power trim, I believe it is either an alpha or pre alpha since it is a 1980. Anyways, I took it out last week for the first time in a couple months and had a major problem at the end of the day and actually had to get towed in. We were on the lake for about 4 hours, the boat was running great, but then all of a sudden after about a half hour of trolling I started to hear a slight grinding noise. As soon as I heard that I shifted the boat into neutral then tried to shift back into forward. The outdrive would not engage and we were dead in the water. I tried shifting the outdrive manually at the base of the drive but couldnt get anything. While doing that the engine started to overheat. So I shut it down and waited for a boat that could tow us back in. Got the boat on the trailer and couldnt see any signs of the shift cable being damaged but it had already been such an arguous day that I didnt even want to mess with it.

I went back out to the boat yesterday, started it up and saw that with the ear muffs hooked up the outdrive wasnt sucking any water up and pumping it into the engine. I also noticed that the prop wasnt turning at a very slow speed like it usually seems to do while idling in the driveway. I tried to shift into forward and reverse, nothing. Any ideas on what could be going on?

I checked the gear oil, seems relatively clean, no water present. I was thinking shift cable but it doesnt make sense as to why the prop isnt turning while idling. Any suggestions would be greatly appreciated!

Thank you all!

 

[Don S]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

Sounds like you spun the hub of your engine coupler. Look behind the engine for a bunch of metal shavings. The coupler is what turns the input shaft of the drive. No splines, no shift. The raw water pump is also in the drive, when it doesn't turn, it doesn't cool.

 

[nola mike]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

ruined upper gearset will also cause this problem. you should be able to see the outdrive shaft behind the engine; if it's spinning, it isn't the coupler. if it isn't spinning, it's the coupler. bad news either way. it isn't a problem with your shift mechanism if the water pump isn't working.

 

[dingdongs]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

popping the cover on top of your drive off where the gears mesh will tell you if there are any teeth on the gears or even any oil in the drive.if you crank engine over by hand with plugs removed to make it easier you may see whats turning and what isn't.have seen also the splines sheared off the verticle shaft which drives the water pump into the gear shaft of which is visible of the gear looking straight up.good luck in your search and keep all informed of progress.

 

[Bondo]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

Ayuh,... I think Don's right,....
But...
If the coupler looks alright,+ the top gears aren't trashed...

Pull the Lower unit,+ you'll probably find the top of the vertical shaft Sheared off at the o-ring groove...

 

[achris]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

Well, I've seen all 3 of those things, plus one more. Splines in the bottom of the drive-shaft in the top box corroded out. Usually because someone keeps putting the 'O' ring back on the lower box drive-shaft.

Chris......

 

[nola mike]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

manual says to put the o-ring back on--though i didn't on the advice of some here. common thread is that either:
a) your coupler's trashed (pull engine to replace), or
b) your outdrive is trashed.
pick your poison.

 

[zbnutcase]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

And the O-ring is there to keep in the GREASE you apply BEFORE you reinstall the lower. 'nutcase

 

[av8tor3sp]

Re: 1980 mercruiser 140 prop wont turn and engine overheats

Thank you for all of your quick responses! After thinking about it, the engine coupler really sounds like the problem, although if the outdrive is shot then anyone living in southern california will be seeing a galaxie that needs an outdrive on craigslist very soon. Pulling the engine is an undertaking that I will not be able to do myself, so I will be taking it to the person that I bought the boat from to see what he might charge. He is a very skilled mechanic that restores boats and gives me a very large discount on labor, hopefully he will be able to help me out. On a side note how many hours do you all think would be needed to pull the engine and change the coupler? I looked at the price of couplers online and I figured I would be looking at about $200 for the part itself.

I bought the entire boat last year for 1600, and have used it about 15 times so if I do part with the boat I figured I definitely got my moneys worth out of it. I will get back to everyone with the diagnosis and the possible solutions very soon.