35hp Mercury, lower unit will not come off.

[timberman]

Hi all,

I trying to replace my impeller of an old Mercury 35hp engine (I think its produced somewhere in the 80's) and Im getting no succes with getting off the lower unit of the engine.

I removed all the bolts an took the gearshift off at the top of the engine.

The lower unit only is getting about 1 inch lower, but I cant get it any further down. I already spoke to a local dealer, he said that I had to turn the flywheel and maybe that would help. Also try different gears but nothing seems to help, its stuck on something.

I can make some pictures if you guys prefer.

I hope to hear from you guys cause Im quite out of ideas:redface:

Thanks in advance!

 

[timberman]

Re: 35hp Mercury, lower unit will not come off.

Anyone who might know a solution? I still dont have any progress with this annoying problem..

 

[timberman]

Re: 35hp Mercury, lower unit will not come off.

Hmm, Ive read that I have to cut a hole near the shaft (above in the tail piece) and get it hot with a torch and that may take it loose. First going to try some WD40 or other stuff and hope that will help.

 

[ddennis]

Re: 35hp Mercury, lower unit will not come off.

Hang on before you cut! Someone will be along here that can help you out!!

 

[Starcraftguy1]

Re: 35hp Mercury, lower unit will not come off.

I believe that motor has a pin going through the shaft holding the 2 together.Look up the shaft,Do you have a manuel?Get one you will need it,check for the pin.Don't cut anything

 

[timberman]

Re: 35hp Mercury, lower unit will not come off.

I already toke out a pin thats holding the shift rod thats located underneath the carberator.

I have read this topic: http://continuouswave.com/ubb/Forum3/HTML/009982.html


They say that it is common for the driveshaft to "weld" itself inside the crankshaft.

Anyway, I hope to hear from you guys if you now some things I can try.

 

[jimg984]

Re: 35hp Mercury, lower unit will not come off.

tim, wd40 id good idea
its tougher than playing rook tho, lol
JIMG

 

[mark_gober]

Re: 35hp Mercury, lower unit will not come off.

Timberman,

I have a 18HP that I'm sure is pretty much the same motor. On mine, I have to disconnect the linkage from the shifter at the power head. Is your's tiller? Mine is, so if not, disregard. When I shifted from forward to reverse, there is a linkage that pushes/pulls a rod that is heading down to the lower unit. You have to disconnect that linkage. Then I removed the six bolts and it should slide right out. The linkage on the top of that rod may be hanging on the very small hole that it passes through. Otherwise, I can't see any things else that is stopping it. The only things between the upper/lower unit is the drive shaft, the water uptake tube and that linkage.

Mark

 

[Chinewalker]

Re: 35hp Mercury, lower unit will not come off.

There is no shift disconnect on the 35s ('60s model or the '80s version - same idea). They use a splined coupling.

If you are getting a full inch of downward movement of your gear housing, I doubt the driveshaft and crankshaft are rusted together. More likely the exhaust tuner or water tube are hung up somehow.

- Scott

 

[timberman]

Re: 35hp Mercury, lower unit will not come off.

The unit is not really lowered a full inch, more about 1cm I think .

We have made a hole in the tail piece (above) and hung the motor upside down, sprayed anti rust spray at the shaft were its attached to the crankshaft, I hope this is going to help.

Im 100% sure everything is loose, so thats not the problem, its the shaft that is stuck and wont go out, a common problem with this model as what I have heard en read.

If this wont work than we will probaly have to cut the shaft, replace waterpump and reallign the shaft and re-attached it by welding it etc.
My dad is a metal worker so I'll let him do all the hard work.

BTW: whats a powerhead? Im dutch and dont know the translation for that word, is it the engine itself?

 

[mark_gober]

Re: 35hp Mercury, lower unit will not come off.

Powerhead is the top of the engine....aka the engine itself.

Mark

 

[timberman]

Re: 35hp Mercury, lower unit will not come off.

YES! I got it loose!

We used a simple steel construction to push the both parts off each other, worked great. Here are some pictures:

http://img27.imageshack.us/gal.php?g=algmeensideshot.jpg

The impeller is broken, so now its just a matter of buying and placing the new one in and get everything back together

Thanks all for the help and suggestions!

 

[ohmeohmy]

Re: 35hp Mercury, lower unit will not come off.

does a 50 hp 500 4 1972 model thunderbolt come off the same way?
I have been searching on here for the last hour mine is stuck exactly like what you have described.

 

[timberman]

Re: 35hp Mercury, lower unit will not come off.

@ohmeohmy, You can atleast try it the way I did it by putting lots of pressure on the lower unit and I might just pop off,. See the pics and you can see how I did. Might just work for you to.