lower unit leaking

[jdilo1]

I have a 1970 Mercury 200 20hp that I have resurrected. Motor runs great now but I'm leaking water into my lower unit. I put new oil in, run it in a tank for a few minutes then drain the oil out and it's a milky gray color.

So my question is how hard is it to dissable the lower unit and replace all the seals and gaskets? I have good mechanical skills and a SELOC manual but no special marine type tools. Would I be better off taking it to a shop?

Thanks for the help.

 

[Laddies]

Re: lower unit leaking

It's a nuts and bolts type of job and quite with a manual so if I were you I would go for it. Keep in mind that the driveshaft may need a seal sleeve to repair it as they wear quite often.

 

[jdilo1]

Re: lower unit leaking

Thanks so much for the help.

 

[racerdonnie13]

Re: lower unit leaking

I just pulled down my 1966 merc 350 35hp because it was doing the same thing. the only hard thing for me was getting the bearing carrier dislodged out of the case. I ended up rigging up a jig with my press to get it out. mine had also sat in the rain for 3 years after a season of salt water, so you may not have that problem. The cover nut is a bear too, if you dont have the "special tool" make sure you replace the large o-ring on the bearing carrier, and the prop shaft seals. that is what was bad on mine.

 

[JB]

Re: lower unit leaking

The most common cause of water intrusion into the gearcase is reuse of the gaskets under the Vent and Drain plugs.

Did you use fresh gaskets ?

Hate to see you doing major surgery if it is really that simple.

 

[jdilo1]

Re: lower unit leaking

Well the gasket on the fill plug was missing and the vent plug gasket was in pretty bad shape. So I initially replaced both with new hoping that was the problem. Unfortunately it wasn't so here I am looking at replacing all gaskets and seals.

My question now is if I really am getting water in the oil. When the lube goes in it looks pretty much like regular motor oil but comes out gray and milky looking. I've had the oil sitting in a clear plastic cup for almost 4 days now and I don't see any separation. Do I really have a problem?

 

[Mac uk]

Re: lower unit leaking

Ive got a 200 20hp Lu im trying to strip down. Ive drowned it in WD40, I had a plate Laser cut in the shape of the nut and welded a tube onto it. I fixed a half inch socket from a knucke joint in the top and used a 12v torque wrench on it. Didnt work though. Reads easy in the Seloc manual but you try it.

If you do decide to strip it. the cover nut and bearing carrier are cast Ali and easy to break. Id get a price of a marina first a weigh up their cost to the cost of replacing the nut and carrier if you break them.

If you go for it and do ok then let me know how you did it.


Good luck.

 

[Laddies]

Re: lower unit leaking

First if the oil turns gray you have a leak. The easiest way to break a carrier loose that is stuck is to remove the nut, put 2 wide steel plates across the opening or 1 with a large hole if you don't have a junk prop around then use anything to space out to the end of the prop shaft leaving enough room for a thick washer or plate install the prop nut and tighten the nut to pull the carrier you may have to change the amount of spacing as it comes out. We have used this on engines that the factory puller won't touch for years and never had it fail.

 

[Mac uk]

Re: lower unit leaking

Hows the best way to remove a pain in the a** stuck cover nut

 

[jdilo1]

Re: lower unit leaking

I spoke to a Mercury dealer today and he seems to think the water is coming from around the driveshaft seals because the shaft may be rusted and pitted. So I'm assuming that's where I would use the seal sleeve that Laddies mentioned.

Any idea on where I could get one of those? Thanks for the help.

 

[Laddies]

Re: lower unit leaking

Check the drive shaft for exact diameter, then go to a auto parts store and ask for a seal sleeve for that size shaft.

 

[Mac uk]

Re: lower unit leaking

Can you get the drive shaft seals from an auto place instead of the expensive ripoff marinas?.

Still cant get the cover nut off mine, Ive drilled it in several places and broke a bit out but cant get the rest out. stiil say its a funny shape, its rebated on the bottom inner edge.

_____
| |
| _| -- Cover Nut shape
|__|_
| |
| | -- Bearing Carrier
|____|

 

[hamit59]

Re: lower unit leaking

Mac,
Most times I don't ever try to save the ring nut. We get motor from the sail club. 2hp to 20 most have been in the water all year around. with very little care (sail boat owners) When We see them well it's to late to worry about a ring nut. When the gears are trashed.I drill them I three places break them out.I use tread comb to restore the threads on the gear box .
Oh I have found that wd 40 was made for a water displacement. I like Kroil or pb buster for penetrating oil.

 

[jdilo1]

Re: lower unit leaking

Check the drive shaft for exact diameter, then go to a auto parts store and ask for a seal sleeve for that size shaft.

Planning on working on this over the holiday weekend. Do I measure a section of the shaft that is not worn or the worn portion? Also, how precise does this measurement need to be? Can I use a tape measure or do I need to use calipers to get very specific.

Thanks again for all the help.

 

[Laddies]

Re: lower unit leaking

It needs to be measured in thousandths, you need to measure it where it is not worn and the sleeve is very thin and slides over the shaft, use some loctite to seal it to the shaft and keep it from moving.