Merc 140 lower unit issue

[Merc140]

Hi all.
Bought a 79' Runabout in January and have been having a good time fishing and boating around here on Lake Washington. Yeaaah.
Last couple times out Ive gotten signs of a needed water pump replacement so I decided to do it this past week.
Im way above average in mechanical ability and have a manual etc. but Im stuck and dont want to break everything so I thought Id ask.

I followed the procedure to remove the lower unit by the book but it wont come off. Never been in salt water by the way. Brackish at most.
All bolts are off. the unit has a space of about a 32nd that opens and closes as I pull back and forth. There are also other pry marks where someone has had the lower unit off before. (or maybe tried to).

Is there a secret handshake?
can the driveshaft seize in a bearing race up top somewhere?
The book didnt mention it but is there a shift linkage to un hook somewhere?

Ive got it in Neutral as the book suggests. i even tried it in fwd and reverse.

Ive gone too far to turn back now. Maybe a bigger hammer? Ha!

Thanks for any help!!

 

[emckelvy]

Re: Merc 140 lower unit issue

So you got the "secret" bolt that's under the trim tab too? That's usually the one that gets you!

Beyond that, you've got one at the front, one on each side, 2 from underneath, plus the pesky trim tab and hidden bolt.

If she's not wanting to come even the least bit down once all those bolts are off, I'd say it's likely the driveshaft is stuck in the crankshaft.

Seems odd though because that year motor has a stainless driveshaft and improved seal assy at the bottom of the crankshaft, which was supposed to help prevent this.

Haven't seen a terrible amount of Inlines stuck like this unless improperly assembled by the last 'mechanic'.

The shift shaft has male splines which correspond to the female splines in the upper shift rod. So, they just pull apart. Sometimes they will corrode together, but usually the shift rod will pull out of the lower unit with a bit extra force applied. Then of course you've got the fun of getting the shift shaft reinstalled, but I know the secret for that!

The only other thing I can think of is if the exhaust tube was badly corroded into the lower unit. But being a fresh water motor, everything should just 'fall' apart.

You might try using the upper 'side' nuts as jacking points. Put the nuts back on and screw them down a ways until there's stud showing. Then, load up the top of the stud with flat washers until you can't get any more in.

You'll be able to apply a lot of force with the fine-threaded nuts using this method. Not a lot of travel but it might be enough to bust things loose.

If you can get hold of some very thin machinist's metal wedges, you can get those in-between the 'split' and apply a lot of prying force. Don't use screwdrivers as they're not wide enough to spread the load out and will likely break something.

If you have a "Wonder Bar" kicking around, that would also make a good prying tool.

If nothing else, a set of hardwood or plastic wedges would be better than nothing.

Hope that Helps, let us know what happens..........ed

 

[cannonford57]

Re: Merc 140 lower unit issue

well said master chief

 

[Merc140]

Re: Merc 140 lower unit issue

Well I spent the afternoon messing with it and finally got it off and prepped to go back together. The impellar was missing two vanes and three others were cracked real bad. Im gonna need to go get a few nuts and bolts to re-assemble so I'll save that for tomorrow,

Gotta say thanks to you emckelvy. I did have everything apart and the driveshaft WAS siezed in the crank. When it finally came out you could see the chatter marks on the splines.

All I needed was someone to say "bigger hammer"

It took 6 prybars, in and wedged before it gave its first centimeter.
Its scary smacking and prying on all that aluminum.

Turned out fine though.

By the way, does "emckelvy" have any Navy connection? (electronics mate chief Kelvy?)
Just wondering. I got out in 92' as a QMC

Thanks again!!

 

[Chris1956]

Re: Merc 140 lower unit issue

Clean the corrosion off the driveshaft before you try to install the new impeller. If the driveshaft has rust, it is likely an older lower unit was substituted. Don't forget to grease the splines of the driveshaft and shiftshaft. Use some marine grease. I coat the entire driveshaft with a bit of grease, since I boat in saltwater.

 

[emckelvy]

Re: Merc 140 lower unit issue

By the way, does "emckelvy" have any Navy connection? (electronics mate chief Kelvy?)
Just wondering. I got out in 92' as a QMC

Thanks again!!

Nope, just "E" for "Ed", you know, like Mr. Ed, "Hello Wilbur" !

Looks like I got a promotion, not sure if I like Ensign though; Master Chief has a lot more clout!

Although I wasn't in the Navy, I've worked around Navy personnel for 33 years.

In fact, I'm working for a Retired Master Chief of the Navy who just happens to have been C.O.B. of one of those Big Black Sewer Pipes running around in the depths!

And don't know if it counts but I did my apprenticeship as a Marine Electrician. So I knows my ways around a few trons, and can claim to have grad-e-ated from One Wire Electrician to Two (and sometimes) Three-Wire Electrician!!!

Well, glad to hear you got 'er whipped into submission! Now you'll be able to enjoy this beautiful sunny weather we've been having in the PNW lately. Just watch out for the winds on Lake Washington, they should be pretty fierce in this hot weather.

If the Merc conks out, just hoist sails and away you go!

Happy Boating...........ed