Mercury Lower Unit 101

About inboard or outboard motors.

Moderator: Bill Edmundson

User avatar
Roberta
Posts: 5946
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Mercury Lower Unit 101

Postby Roberta » Thu Nov 10, 2011 10:02 am

Thanks, John!! With all this time on my hands, I am always looking for something interesting and challenging to do. Yesterday I finished the outboard, finished repairing the loose valve seat on our Onan motor in the tractor, and cleaned up the shop. Today I am heading to Badger Hardwoods to find some mahogany for that Super Spartan. Never a dull moment!!!

Roberta :D :D :D :D :D

No rest for the WICKED :twisted: :twisted: :twisted: :twisted: :lol: :lol: :lol: :lol: :lol: :lol:
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

swndlr27
Posts: 1
Joined: Fri Jun 06, 2014 8:42 pm

Re: Mercury Lower Unit 101

Postby swndlr27 » Fri Jun 06, 2014 8:44 pm

I would like to also add that can operate the shift shaft linkage with a 9mm socket. It fits onto the splines.

User avatar
Roberta
Posts: 5946
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Mercury Lower Unit 101

Postby Roberta » Sat Jun 07, 2014 5:35 am

That'll work!! Good to keep this thread alive as many people are getting into their lower units.

Roberta :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

dgates1
Posts: 2
Joined: Sat Aug 09, 2014 1:23 pm

Re: Mercury Lower Unit 101

Postby dgates1 » Sat Aug 09, 2014 1:31 pm

Great post Roberta! Lots of helpful info.

I have a 1969 Mercury 650 4 cylinder and when I removed the lower unit the shift shaft became "stuck" in the power head and pulled out of the lower unit, breaking the retainer clip. I have gotten a new clip among other parts to rebuild my lower unit. I am having trouble getting the shift shaft to release from the power head??

Any tips or thoughts on why it may be stuck? I have moved the shift lever and does not seem to release however I did this by myself and could not pull on the shaft at the same time...

Any help would be greatly appreciated.

Thanks,

David

User avatar
Roberta
Posts: 5946
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Mercury Lower Unit 101

Postby Roberta » Sat Aug 09, 2014 2:22 pm

Most likely the end of the shaft corroded in the socket. If you can get some penetrating oil in the socket, then grip the shaft with a vice grip and tap on the vice grip to help pop it out.
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

dgates1
Posts: 2
Joined: Sat Aug 09, 2014 1:23 pm

Re: Mercury Lower Unit 101

Postby dgates1 » Sat Aug 09, 2014 9:24 pm

Yeah that worked. Thanks.

I made my own tool to take out the shift shaft seal assembly out of an extra spark plug socket I had laying around. Just file it down on the sides to leave two tabs that fit the grooves. It has that piece of foam in it meant to grab the spark plug and it works perfect to line up the tool around the shaft. Also it has an end that can be used with a rachet or a wrench. I've included a picture.

IMG_1902.jpg
This was a lot cheaper than buying the tool. And it still works to take out spark plugs!

andykaut
Posts: 4
Joined: Sat May 21, 2016 7:41 am

Re: Mercury Lower Unit 101

Postby andykaut » Sat May 21, 2016 7:47 am

Okey, folks. So I'm trying to put my Merc 500 together and have used these posts a few times in the last few days. Thank you so much for a clear and concise explanation of the problems I'll run into during the rebuild, and thank God for all of your helpful hints.

The cables up top are a complete mystery wrapped in an enigma to me, however. I will get the switching correct on the engine side, but the Mercontroller seems to move both cables a little, and I'm not sure which goes where any more.

As well, there seems to be a choke/cold-start lever on the backside of the controller that does some other rather odd things with the cables. I'm half-tempted to change it out, but I'm sure it could be serviced if I could only figure out exactly what the heck it all does.

That and the button labelled 'choke' seems to do absolutely nothing; to choke it I have to hold my finger on the connecting rod between the two carbs.

Any comments and/or help would be appreciated. Such as, is there supposed to be a choke cable? There's a corresponding hole in the top of the cowling, but I don't know if that's for a rod, though it would make sense that its for a cable. And if so, where would this (apparently) missing cable attach to the Mercontroller?

andy.

User avatar
Roberta
Posts: 5946
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Mercury Lower Unit 101

Postby Roberta » Sat May 21, 2016 8:25 am

On the Mercontrol, The first cable to move, when operating the control lever, will be the shift cable. Once the shift into fwrd or rev is completed, the throttle cable will move to open the throttle. The lugs on the cable holder in the engine compartment are engaged into the cables. The upper cable will be the throttle.

On the Mercontrol, the lever by the control handle is for a fast idle. Lifting will engage the throttle slightly for fast idle and engine warmup.

The choke button is for the electric choke. The should be a manual lift for the choke on the motor and a solenoid on the linkage for electric operation of the choke,

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

andykaut
Posts: 4
Joined: Sat May 21, 2016 7:41 am

Re: Mercury Lower Unit 101

Postby andykaut » Sat May 21, 2016 8:33 pm

K,

I figured the choke bit out now, it seems I'm missing the plunger from the solenoid.

Anywho. Got the whole leg back together and she's still leaking oil pretty good out the bottom. Bloody frustrating, I changed the prop seal and put a new water pump in.

Must be missing a seal - there was a groove in the bottom of the water pump housing that could have held an o ring, but I couldn't get it to fit in with ring present. Could this cause oil to get into the leg?

(Sorry for the 2x post; it seems I wasn't ready for the delay in posting and thought maybe this one hadn't been rec'd.)
Last edited by andykaut on Sun May 22, 2016 5:45 am, edited 1 time in total.

andykaut
Posts: 4
Joined: Sat May 21, 2016 7:41 am

Re: Mercury Lower Unit 101

Postby andykaut » Sun May 22, 2016 5:31 am

Okay, I've got that figured out and back together, but it still looks like the darned thing is leaking. I only have two more o-rings that I didn't figure were ultimately necessary when I took it apart. One around the carrier and one at the base of the water pump lower housing. I guess it will be the latter; it leaks way more when running.

There is an electric choke solenoid, but it looks like its missing a plunger inside of it. There's nothing connecting it to the choke linkage.

It backfired twice yesterday when it was putt-putting and spewed oil onto my siding. I'm thinking there has to be a leak. Its not shipping oil via water pump, but it sure as heck isn't sealed as well as I'd like it to be.

And another question (I've got no shortage of things I don't yet understand...) what's the plug in the front of the mercontroller for? Right now its running the power to my fishfinder, but this just through silly little wafer-contacts. The whole engine electrical seems a mess, as I also have a spare 'mystery wife' under the cowling that just sorta hangs out. No evident place to put it, yet. I haven't tried grounding it while she's running.

andy.

P.S.- Thanks for sharing the road you've already walked. I have a BIL from ontario that is convinced the spine will break and sink the moment she sees water, and is therefore refusing to help. I've got mechanic friends, but none of them that have ever fixed up a boat before. :)

User avatar
Roberta
Posts: 5946
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Mercury Lower Unit 101

Postby Roberta » Sun May 22, 2016 9:15 am

Thanks, Andy.

Under the water pump there should be a gasket and an o-ring to seal the pump base. Then there are two oil seals to seal the pump to the shaft, Read carefully in my assembly instructions on how they are oriented. If your shaft has a groove in this area, that is a problem and will need to be repaired or shaft replaced.

The inner larger o-ring on the big gear carrier by the prop shaft is easy to damage. care must be taken in assembling this part to ensure it seats properly.

If you have the manual for this motor, there should be a wiring diagram to help sort out the electricals.

Hope this helps,

Roberta :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

andykaut
Posts: 4
Joined: Sat May 21, 2016 7:41 am

Re: Mercury Lower Unit 101

Postby andykaut » Tue May 24, 2016 5:20 am

Yesterday the SS POS II saw water for the first time in my ownership. There were some legal difficulties to overcome (i.e. no VIN / valid plate), but with an impatient wife inside the house and screaming toddlers outside, I decided that it was time to take her out. We fit/crammed the whole family (5 of us, counting the baby) into a 14' skiff. The 50 HP wouldn't plane with all of us in it, but that's the only smudge on the day.

Had a little trouble loading it - probably buried the trailer just a little bit too much. Still getting a feel for that.

The throttle needs to go an outrageous amount to the fore (prob. to at 8, maybe 7:00) to max out on the Mercontroller. Not sure if its warn or if that's the normal range of motion.

I got the choke working after your last post - it turned out what I thought to be a weight that held the choke open was indeed the plunger for the choke solenoid. I sanded it a little (it was tight in the top) and added some fish oil. It works with a touch now. So far as the o-ring under the water pump, I'm not sure if I'm going to continue tearing apart the motor. It deserves a new shine, and I shall hopefully monitor what's going on with it. But short of shooting some Sea-Foam (I guess its called) into the carbs and using some chrome polish on the beautiful front plate, I would rather use it this summer than fix it the whole time.

I put some seats in her, which I'll have to get some pictures of. Two x 13" square box w/ 2x2 and 1/2" painted a utility grey (same as the new floor I put in) and then just bolted some Costco purchases onto the top. I left the fronts open for storage of tackle, and I'll do the same once I build the back bench. Two rows of seating will probably pretty much be it for the room I have on her.

I'm almost at peace with this restoration thing - yesterday we were unloading next to boats worth 50-60k (we live in Oil Country, Alberta), and at the launch an older fellow complimented us on a 'well-taken care of old girl'. I can barely wait to bring my 1950's BellBoy home and start on her.

BradO
Posts: 1
Joined: Sun Jun 19, 2016 9:20 pm

Re: Mercury Lower Unit 101

Postby BradO » Sun Jun 19, 2016 9:27 pm

1973 Merc 500 outboard 50

Prop struck in reverse. I have taken The lower end out of the motor and when I manually move the shifter linkage in all three points forward neutral and reverse it moves freely and the prop remains in reverse. So in all three positions forward neutral and reverse the prop is running in reverse. I have a torn the innards out of it yet just wondering if anyone could give me any insight on what could be the problem. thanks in advance!! I have torn many of these apart and I have never ran into this issue

User avatar
Roberta
Posts: 5946
Joined: Tue Jul 31, 2007 5:23 pm
Location: East Troy, Wisconsin

Re: Mercury Lower Unit 101

Postby Roberta » Mon Jun 20, 2016 5:37 am

The spring in the clutch ratchet normally pushes the clutch to the forward drive position. Something is preventing the clutch from disengaging the reverse gear. A missing pin or broken spring could be the problem. Could also be the cam follower is stuck or the clutch is stuck on the shaft. You will need to remove the prop shaft from the housing to inspect the assembly.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".


Return to “Boat Power”

Who is online

Users browsing this forum: No registered users and 4 guests