Lower unit oil leak

[alltypesofstuff]

Hey guys, I've got a 4.3 LX Merc Alpha 1 I/O
It's leaking gear oil out of the small hole in the back of the lower unit. (what is that hole btw?) I bought a lower unit gasket set and managed to get the unit off. When I did so I found a lot of water in the back of the housing by what I think is the gear shift? Also the pipe that I believe delivers water up the unit and into the engine looks fried. Any thoughts on the oil leak/water issues? Thanks

I posted pictures of
The hole I mentioned
The water hose that looks fried
The area that was full of water
And just another looking up into the upper unit.

Thank you again for any help

 

[Bt Doctur]

Re: Lower unit oil leak

pic 1, water guide tube.melted from hi exaust temp and low/no water flow.
pic 2 copper tube and water pocket cover, they look ok
pic 3 drain hole from water pump area
pic 4 is a cavity that leades to the drain hole.
Either the water pump base seals are bad, the shift shaft seals are bad, or the upper unit driveshaft seals are bad.

 

[Don S]

Re: Lower unit oil leak

The only way to find a leak, is to drain the gear lube and do a pressure check of the drive. A spray bottle with some soapy water in it works great for finding leaks, (the leak blows bubbles).

Since you have the drive apart, just plug the oil passage between the upper and lower and pressure test each half separately.

 

[Oshkosh1]

Re: Lower unit oil leak

The driveshaft upper oil seal(pic #2, partially obscured by copper pipe) is toast. Oil will drain from the upper unit into the lower cavity and exit through the weep hole(the hole in question) which drains the lower void.

 

[alltypesofstuff]

Re: Lower unit oil leak

Ok great, so water in that cavity is ok and normal? Probably not normal that it wasn't draining out though right? So I'll try to clean up that drain hole.
I have all new water pump seals that came in the lower unit gasket set so I'll replace those anyway.

Do I need to replace that water guide or does the copper pipe do all the actual work there and the pipe is exactly that, just a guide?

And replace the driveshaft upper oil seal.

I do believe I read that the water pump itself should be replaced every year? Good idea to go ahead and replace that now too then I suppose.

 

[ktbarrentine]

Re: Lower unit oil leak

Hey guys, I've got a 4.3 LX Merc Alpha 1 I/O
It's leaking gear oil out of the small hole in the back of the lower unit. (what is that hole btw?) I bought a lower unit gasket set and managed to get the unit off. When I did so I found a lot of water in the back of the housing by what I think is the gear shift? Also the pipe that I believe delivers water up the unit and into the engine looks fried. Any thoughts on the oil leak/water issues? Thanks

I posted pictures of
The hole I mentioned
The water hose that looks fried
The area that was full of water
And just another looking up into the upper unit.

Thank you again for any help

Good replies so far...also, you need to re-orient yourself to the drive. What you are calling the "back" is actually the front (forward end).
I recommend that you get the whole water pump kit that includes the pump impeller, the pump housing, base, gaskets and O-rings, and the plastic guide tube you need to replace.
If the upper driveshaft seal is in-fact bad (as will be evident in a pressure test), then you actually have two seals up there that need to be replaced, and the upper of the two is only replaced by dis-assembly of the upper gearset (the lower of two, a grease seal for the vertical shaft splines, is replaced from below and is easy to get to with the halves split). Are you up for replacing those seals? There are several threads on here about that topic. (I would say by the photos that there is oil sheen evident coming from this seal area, but that could be from other causes coming from the dis-assembly). Pressure test both halves independently, and then when you are all done replacing seals and putting the halves back together, do a final combined pressure test before putting new oil in it. HTH... Best of luck! (BTW, My guide tube looked just as deformed as yours, and the rest of the drive looked like yours on my first impeller and seal job on a new-to-me used alpha-1 drive, and now the drive is operating great!)

Oh, and yes, water in that area where you found it is normal, but should drain out through the weep-hole you originally saw the oil coming from. It is especially important to keep this hole clean so it will drain water, so in case it gets real cold where you are, it wont freeze and crack the casing! (ok...you have to do all that other winter-stuff, too! But what do I know? It never gets that cold where I am anyways!)

 

[alltypesofstuff]

Re: Lower unit oil leak

Yeah I guess that makes sense when you call it the forward end lol.
Thank you for all the great advice and for the encouragement, misery loves company I suppose and it's nice to know someone has gone through it. I don't think the guy I bought the boat from took care of it at all.

Yes, I think I can tackle taking the upper unit off too. I'm about to order the rest of the seals and what not but can someone confirm the upper unit seal kit for me. This is what I'm looking at:

Upper Unit Seal and O Ring Kit for Alpha One Gen II Compare to 26 88397A1 | eBay

I actually don't have an air compressor to do a pressure test with. I've been on the look out for a cheap yard sale one but keep in mind I'm just a college student on a college student budget.

And I'm south of Miami so I don't think I need to worry much about freezing! But I'll make sure to clean that weep hole out well regardless.

 

[ktbarrentine]

Re: Lower unit oil leak

You dont have a gen II..... provide your drive serial number. (year gets close, but there are differences..... most likely an alpha-one, 1990 or prior).... Go to places like Mercury Mercruiser engines and parts (example) to look up parts by serial number/year....good pictures and exploded drawings. Then you can cross ref the numbers to places like here, and ebay, amazon for the right stuff.
You dont need a compressor to do the pressure test. There are threads on here (search on "pressure test" or go here: This is from the adult stickys section at the top of this forum: http://forums.iboats.com/mercruiser...sure-check-prior-post-233546.html#post1573303 ) on how to build a simple pressure tester and you can use a bicycle tire pump as the source.

Also..in photo #1 in your first post, you are missing screw #37 in the pump housing.

I wouldnt replace anything until you do the pressure tests and can confirm the scope of what you need (especially since you are on a tight budget.... dont buy what you dont need).

 

[alltypesofstuff]

Re: Lower unit oil leak

Ok I finally got some time for the boat again. The serial number on the stern drive is faded but i believe it's 0C313908
I came up with R/MR Alpha One?
And thanks for the info, I'm working on the pressure tester now.

 

[alltypesofstuff]

Re: Lower unit oil leak

This one here says that it fits most R/MR models, is there a way to tell if it's for mine or not?
Upper Unit Seal Kit Mercruiser Pre Alpha One Generation 1 Outdrive 1973 1990 | eBay

 

[ktbarrentine]

Re: Lower unit oil leak

When I order things like that off ebay, I generally cross my fingers and hope the description is correct (this one matches your description), then match up the pieces as I take my rig apart. If it turns out not to be the correct one, then I go somewheres else, like iboats, mercruiserparts.com, amazon.... good luck!
How did your pressure test go? Any "smoking gun?"