is this normal? mercury 9.8 (water in lower unit, oil) (((Pictures Included)))

[boater1111]

i just took lower unit off, and water dripped out, is that bad? then i pulled drain plug and oil was that milky color, does that mean water mixed in? if so, where? and the oil barely came out, it is so thick, and it feels like not much is in there...oh boy i dont think this is good. what do you think?

 

[Texasmark]

Obviously the goo is petroleum and water. I was going to say exhaust slobber from too much trolling but you got me on the right track. A pressure test on the order of 5 psig and immersion of the lower unit in a tub of water will show you your leak. Normal places are drive shaft seals (back to back) under the water pump, prop shaft seals (back to back) right in front of the prop in the prop shaft bearing carrier casting, shift shaft seal....very close to the front of the LU casting on the top....forward of the water pump, and drain and fill screw gaskets. If not there you are in deep doo do as it is probably a cracked LU casting.

With all that mess around the water pump, my first guess would be the seals under it are bad. If your engine is 15 or so years old, mite as well get all of them and be done with it.....if seals is your problem, and a water pump redo too. Wallmart has the Merc. lower unit gear oil in the sporting goods section.

 

[racerone]

There may be an issue with the bottom CRANKSHAFT seal.-----Replace the seal on the driveshaft and the seal on the propshaft.---I believe there is only one seal on these and not back to back.---Serial # or year ?

 

[Chinewalker]

Definitely two things going on here.

Yes, you're getting water in your lower unit. If the lower unit oil you're seeing is old with lots of water time on it, then I would drain, refill and keep an eye on it. Crack open the bottom screw after a few outings to check the color. If it turns milky quickly, then you'll want to address that.

Second, the goop in the housing itself aft of the water pump is unburned fuel/oil mix. Might point to lots of idle time, or a carb that's in need of rebuild or set too rich, or a mis-fire on one cylinder leading to excessive unburned fuel dumping down the exhaust. In any case, that's quite a bit more than I'd expect to see on a health, good running motor.

 

[schematic]

the driveshaft is likely rusted out where it enters the gear case. This makes for a bad seal surface for the upper seal....
Oil enters the water pump and makes a mess..,..

 

[Texasmark]

the driveshaft is likely rusted out where it enters the gear case. This makes for a bad seal surface for the upper seal....
Oil enters the water pump and makes a mess..,..

Interesting comment. Back in 1965-6 time frame I was in a Merc dealer in a salt water area. Merc 90 had the lower unit off and I couldn't believe my eyes when I saw the drive shaft.....carbon steel.......scabs and scabs of rust scale. I was an OMC guy at the time and OMC has had SS drive lines for as long as I can remember.

Since you made the comment, do you know when Keik. went to SS drive lines?

 

[schematic]

Since you made the comment, do you know when Keik. went to SS drive lines?

I'm not sure. Late 60s early 70s?
Canadian serial numbers are usually a pain to pin point to the year.
Still lots of the ole rusties around here. Every so often a real primo will come in worthy of a shaft repair.

 

[Texasmark]

I'm not sure. Late 60s early 70s?
Canadian serial numbers are usually a pain to pin point to the year.
Still lots of the ole rusties around here. Every so often a real primo will come in worthy of a shaft repair.

I don't guess I'm hijacking the thread as things are slowing down and this is related. Seems to me that from a mechanics standpoint, having to do any kind of maintenance on a carbon steel equipped engine would be a real pain......just take for example servicing the water pump. I'm telling you, that really turned me off Merc. and it was a lot of years later before I left OMC and went Black!