Gettin into the lower unit

[hag]

I have a: Mercury (7059157 Serial#)
65 hps 1975
Canadian motor.

Lower unit leaking water in. Probably because of stripped oil plug I will fix but need to get into the lower unit to do it.

But seems to be one solid unit. Have not seen anything like this before so good learning adventure but need help.

Hag

[beerman57]

Have to go in through the water pump cover and prop shaft seal cover. Go to marineengine or seaway websites and look at the parts breakdown.

[hag]

Thanks beerman57 but was hoping for more detail, I actually have a manual but it’s up north in canada. I brought the lower unit home but forgot the book.
Well guess I have to wait until I get up there.

[beerman57]

You just need a spanner wrench and look at the exploded view of the L/U at one of those websites. If your ’75’ L/U is similar to Merc MK’s, after you get into the prop shaft area & remove the shaft w/gears, bearings, etc. – remove the bolt holding the pinion gear. Then with the pump cover off, if you don’t have all the special merc tools, clamp the driveshaft in a vice, use a block of wood and tap down on the L/U to pull out the impeller cup (or does a ’75’ have a "modern" water pump?) Catch the L/U in something as you tap on it to remove the shaft, or have someone hold it for you. I’ll go take a quick look at seaway to see what your L/U is actually like.
NEVER MIND – your L/U is more "modern".
Your only problem will be getting the "nut" off, holding in the bearing carrier and everything else. Go look at one of those websites, nothing that hard to figure out!

[hag]

Well got it apart just fine, glad I did the bearing carrier was cracked , got that replaced changed the oil rings on it, no problem.
Problem is the pinion gear, it’s bad several teeth seem crushed or broken off. Got a new one but having trouble getting the nut off to change it. I presume it had been secured with lock tite. Tools seem to slip off and they are tight, don’t want to strip it.
Any suggestions?

[jeff-register]

Hag,
Sounds like your ring gear is running to high or your pinion gear is too low. What shims did you find when you took it apart. Sounds like someone before you has messed up the alignment. I have made a few tools for removing the carrier nut. Go to a junk yard & get a piece of metal & drill a hole for the prop shaft then drill two holes for the pins. It works great if the metal .5" thick or more to hold the pins straight.
Look for the shims in the old lower unit & save them, you will need them to set up the new gears. Takes time to set them up correctly, have your book sent to you. Have you ever set up a Mercury gearset? If you take a 7/16 6 point box end wrench & sand the rounded side of the box end until it has no bevel & straight 90 degree config the pinion bolt will seat much better & not slip off. Use a vice grip on the driveshaft to keep it from turning it will come off. If I was you I would use the pinion & ring gears together as your old gears may have transferred damage to the other meshing gear, worth a look at any rate. Do not put pressure against the gearcase with the wrench you run the risk of breaking a chunk out too. The Mercury gearcases are thinner than OMC stuff too.
Jeff

[hag]

Thanks Jeff,

Well, I like your spanner tool I think I will make it but still get one from the hardware store also not too expensive.

Can you post picture of the modified box wrench? The pinion gear nut is proving to be a pain.

As for the other gears, the forward gear is fine and intact, the reverse gear had some damage to it along with the bearings. That was replaced with the new bearing carrier.

Once I get pinion nut off I can check the alignment of the teeth of the new pinion with the rest of the teeth.

[cajuncook1]

quote hag:

Thanks beerman57 but was hoping for more detail, I actually have a manual but it’s up north in canada. I brought the lower unit home but forgot the book.
Well guess I have to wait until I get up there.

Hag, if you PM me with email address, I can send you a couple of digital manuals. They are quite large.

[hag]

I just sent you pm (2 actually) but it says it was sent but stays in the outbox not the sent box. Not the way I’m used too. Did you get them ,Cajun?

[cajuncook1]

Hag, I got your email address. Check to see if you received a link from wetransfer.com. Click the link and download the files. They will be zipped files, so right click on the file and choose the option to unzip the file and you should be able to view them.

If you have issues with the above process, let me know and I will send you a drop box link.

Please let me know.

[Author]

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