*Updated that is a vent PIC* 1967 120 I/O water in unit lube question.

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1965GTFB

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[/IMG]1967 Mercruiser 120 I/O Question. For the past few years I have had the problem of water getting mixed in with the outdrive unit gear lube. I drain the lube(and water) each year or after a trip with a lot of use to keep too much water from being in there at one time(I know any water is too much water). I think it mainly gets in during higher speed operation because when I am on my slalom ski with the boat running about 3,600 rpm I will see lube(looks like pancake batter) coming out of the overflow vent at the top back of the unit. So once enough water has gotten in it is forcing a water/lube mix out the vent. It does not do it until after a few runs or days on the lake depending on how much I ski and doesn't seem to do it at the slower speeds used for wake boarding. I have replaced the seals between the two halves of the unit at least a couple of times during other maintenance but can't seem to stop this. Also replaced all the big o-ring seals the lower unit the last time, water still got in and forced stuff out the vent. It seems that the water must be getting in under some kind of pressure to force fluid out the vent.
Questions:
Is the little passage between the two halves that gets the o-ring the most likely point of entry for the water?
Since it seem the water must be coming in under pressure would the water pump some how be involved?
Should I be using some sealer, like permatex ultra black, on all the water pump gaskets and other seals?
Any other ideas?
I know water in there is BAD and I'm getting tired draining and refilling the unit with lube, including having to pull it off the lake mid-week on longer camping trips to drain and refill it.
Help & thanks.
 
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NHGuy

NHGuy

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

You need to pressure &/or vacuum test the drive. Then depending on where the leak is you will be able to research whether you fix the leak or pay someone with the right skills and tools. The teardown and assembly tools for a drive are pretty uncommon and ain't cheap.
 
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boattech

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

O-rings rarely fix a leak in an outdrive. Most common seals to leak are the shift shaft seal, and water pump base seals. The o-ring between the two drives rarely ever gives problems unless installed wrong. The only other seals allowing water to enter the drive would be the propshaft seals or the upper driveshaft seals. If you are not willing to reseal the whole outdrive i would start with the shift shaft seal and water pump base seals! AS the previous poster said pressure checking would point out the problem quickly
 
cr2k

cr2k

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

There is NO overflow/vent on the outdrive. That is probably where your leak is.

I and guessing you are referring to the small rectangular looking hole on the back of the top of the drive just below the top cap? That is just a pry space to pull the top cap. Your O-ring is probably shot at best, you really do need to have it resealed and pressure/vacuum tested, unless you want to replace it this summer. Or are you referring to the oil plug on the top of the drive? It sez vent but it is to vent the air out as you fill with oil from the bottom and then is sealed with the plug and a new drain plug seal every time as the bottom plug should be.

There really is NO way to get out of servicing a boat. If you don't do it as required regular maintenance you will have to pay for costly repairs eventually.
 
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1965GTFB

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

It is the small rectangular looking hole on the back of the top of the drive just below the top cap. That is where I have seen it coming out with my own eyes while skiing. Again, it seems like the higher speeds/rpms of skiing is when it pukes out the pancke batter. I'm pretty sure I'm just going to go through it and install all new seals since I am do to install a new water pump impeller too.

I already did that about 4 years ago with the advice of a local shop and them doing some of the work. Not sure that I'll have the shop touch it again since they broke the housing in the lower unit trying to remove it the last time, even though I took it to them since they had the "correct tool for the job". This is not a corroded old unit, it has never seen salt water, always garaged with limited use each year.

Maybe I should just do it all myself this time. If I can build this with my daughter and it know has 103K miles in nine years I would hope I can handle sealing the out drive?
05_jenny_mustang.jpg

http://www.meguiars.com/shiningstars/
My daughter assembled her cylinder heads herself so maybe I need her help:redface:

I need to read up on the pressure/vacuum testing procedure and do that. Is the testing done with the unit on the boat or after it is pulled? Also should a sealer be used on all the gaskets?
Time to build a pressure tester.

Also where is the best place to get seals and parts for some thing as old as my 1967?
Thanks all.
 
cr2k

cr2k

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

Any MCM dealer of even NAPA auto parts has a marine catalog. Your parts are still available.
 
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boattech

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

Buy a service manual that will help. There are several special tools you will need to disasemble the outdrive, and there are several tools for each seal that installs them at correct depths and keeps the seal from distorting. When you are taking it apart take your time and watch for shims. there will be shims in several places on that outdrive and you dont want to loose any or not see where they fell out of. Honestly if you want to do it right the tools will cost alot more than a service shop should charge to reseal it. If they are honest and compatent they should be able to pull the drive, reseal it and reinstall it in 3-4 hours labor.
 
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spect8r

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

Pull the outdrive yourself and take it to a shop for repair. It's easy to do and will save the labor for this part of the job.
 
Eric 3.7LX Alpha 1

Eric 3.7LX Alpha 1

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

If you go to the "Adults Only" at the top of this forum at the bottom there is a link on how to make a pressure tester for your drive. If you remove the drive, you can submerge it in a kiddie pool or the like to see where the bubbles originate from.

A long term leak like that will eventually cost you a new drive. My drive leaked very slowly from the prop shaft seal from wire line getting wrapped around it. Well I just kept refilling it as I would use the boat. (trailered). This year my upper half top bearing was toast from that leak. Now Im using a spare complete drive.

It's like going to the dentist, it isn't goin away on it's own.
 
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1965GTFB

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Re: 1967 120 I/O water in unit lube question.

Re: 1967 120 I/O water in unit lube question.

I built a pressure tester and used it today. Results are in this new post http://forums.iboats.com/showthread.php?t=416505
So now knowing that my cap does have a vent, everyone kept telling me they don't, and that is where the goop was coming out under higher rpm power I should plug the oil passage hole from upper to lower and pressure test just the lower.
 
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