White milky oil from out of the side of Lower Unit??

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nortac

Recruit
Joined
Aug 23, 2003
Messages
4
Hi, I’m new here but have a question. I have looked in previous pages and did not see the same problem I am having. I have a 1983 Merc 150 outboard. I purchased the motor and boat last weekend. I took the boat out and everything was fine motor ran great but a little slow coming out of the hole. It has a 24pitch prop and the blades where a bit flat.<br /><br />I brought the boat home where it sat for 6 days and no leakage. Friday, I took the boat up and had the prop removed so it could be repaired. Brought the boat home without the prop on and parked it Friday afternoon. This morning I noticed a small pool of oil on the ground below the motor. After inspection the oil was coming from the right side of the LU out from one of the holes. There is one hole in the exact same spot on the left side and then the drain plug next to it on the left side. The right side just has the two holes. The oil is milky white and is coming from the hole facing toward the boat. I’m not sure what the holes are for exactly they are about ¼” in diameter. <br /><br />I realize water is getting in the oil, just wanted to know if anyone knows where it is coming from and how to correct it.<br /><br />Thanks so much<br /><br />Eric
 
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andrewkafp

Lieutenant Commander
Joined
Mar 15, 2003
Messages
1,668
Re: White milky oil from out of the side of Lower Unit??

You have a drain (Bottom) and vent (Top) screw.<br />They are about 1/2 " diameter and when they are removed, there should be a small plastic seal either on the screw or in the recessed hole. If either one is missing, that is where the water is getting in. Remove both screws, and drain out all the gear oil.(It should be clean oil) Replace the seals, fill from bottom hole 'til it runs out the top hole. Tignten the screws.If the oil becomes milky again or leaks,you need to pressure test the gearbox. This will tell you whether you need to have the main seals replaced. The leaking oil could be unburnt 2 stroke.. which is normal<br />You can tell by smelling it... Gear oil has a distinctive smell and unburnt fuel smells like carbon/petrol...
 
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merc 140 pontoon

Petty Officer 2nd Class
Joined
Aug 23, 2003
Messages
129
Re: White milky oil from out of the side of Lower Unit??

A related question--is there a gasket or seal of some sort between the lower unit (gear housing) and the stern drive upper unit?
 
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andrewkafp

Lieutenant Commander
Joined
Mar 15, 2003
Messages
1,668
Re: White milky oil from out of the side of Lower Unit??

No gasket. Just a layer of sealer on my OB.<br />No mention in Merc manual of a gasket.
 
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nortac

Recruit
Joined
Aug 23, 2003
Messages
4
Re: White milky oil from out of the side of Lower Unit??

ok I looked in side the hole with a flash light. there is a shinny flat metal object deep inside the small hole where the oil is leaking from but not a screw head. the other hole has nothing in side of it. the only screw head is on the left side of motor and that is for the grease. but the leak is on the right side from a different hole 5/16 to 1/4 inch in diameter. what would I unscrew to check and see about repairing and also why didnt the area leak when i first brought it home and it sat for a week and only started to leak after the prop was removed? Again, trying to explain this properly, the holes im speaking about are located approximtely in the middle of the lower unit. Two holes on the right and two on the left in the same place. The back hole on the left has a screw head in it for the grease. but it is leakin from the front hole on the right. There is nothing to unscrew at that spot. Any other ideas?
 
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Merc90HPnewbie

Petty Officer 2nd Class
Joined
Jul 27, 2003
Messages
178
Re: White milky oil from out of the side of Lower Unit??

I looked at Nortac's picture. have some holes like that in my LU also that I can't figure out what they are for. Maybe they run to a speed measuring wheel in the LU? But if gear oil is coming out there, maybe someone overfilled the LU oil and it is overflowing up through that area??
 
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Redrox

Cadet
Joined
Aug 24, 2003
Messages
12
Re: White milky oil from out of the side of Lower Unit??

Unicorn, would a 90hp Mariner (year 1990 probably) have these seals around the oil screws as well? I have had my Lower Unit seals replaced and my lower Unit repaired yet I still get milky white oil (signifying water) when I drain my oil from my lower unit.<br /><br />Thanks!
 
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Merc90HPnewbie

Petty Officer 2nd Class
Joined
Jul 27, 2003
Messages
178
Re: White milky oil from out of the side of Lower Unit??

Redrox;<br />I think just about all lower units have seals on the drain/fill screws. They're really just gaskets that get compressed between the head of the screw and the surface they are screwing in to. If you dont have a gasket on your fill and drain screws it's probably a good idea to put some in. I reused the ones that were already there but I probably should have replaced them when I changed the oil last month. However, I didn't have any water in the oil so I'll just leave it be for now :I
 
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andrewkafp

Lieutenant Commander
Joined
Mar 15, 2003
Messages
1,668
Re: White milky oil from out of the side of Lower Unit??

Well I am by no means any expert, but I haven't seen any holes like those in a L/U before. The one that's leaking oil looks almost "punched" rather that stamped or drilled. Anyway... The important thing is.. When you check the oil inside the L/U it should be clean oil. As far as I know all L/U 's have the above mentioned gaskets, but they can easily roll away, when you take out the screw, or be stuck in the recessed area around the hole. (Check your manual)and buy a couple of bright red or blue ones soyou can see them. Merc90 may be right too,as there maybe just a bit of surplus oil lying around in there that is being flushed out of that hole.
 
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nortac

Recruit
Joined
Aug 23, 2003
Messages
4
Re: White milky oil from out of the side of Lower Unit??

I checked the gear oil from the drain hole. The oil was a bit milky and blue in color. I talked the guy i bought the boat from and he stated that he changed the gear oil about 4 times a year because of this and said the last time it was changed was about two months ago. I didnt notice any metal at all on the drain screw but to be honest Im not sure if its magnetic or not. He stated he has never noticed significant metal on the drain screw as well.<br /><br />Is it ok to just change the oil out every few months and fish the heck outta it or do I need to spend the bucks to get it repaired. I bought the boat because of the price - Very solid boat and motor except for this. Im just concerned Im going to ruin the motor by allowing water to enter and mix with the oil even though it would be changed often....<br /><br />Any ideas? Plus I still dont have any clue why the oil is leaking from where it is leakin in the pic above???
 
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andrewkafp

Lieutenant Commander
Joined
Mar 15, 2003
Messages
1,668
Re: White milky oil from out of the side of Lower Unit??

The small amount of metal on the magnetic srew is insignificant.. I don't even bothering looking at it as there will be a bit of wear on the gears anyway. (Small chunks are the problem)<br />Regarding the water in the oil. If you are happy to regularly flush out and replace the L/U oil it will last longer, but if you allow water to build up in there, it will self destruct from pressure and rust.If it is not the little gaskets, it's the seals in the unit. This is a major job needing special tools. It cost around $500.00 Aust which is about $240.00 US. If you check your manual, it means dissassembly of the propeller shaft, replacing inner and outer seals and re-assem to correct torques. Some things are better left for the Pro's with the right tools.<br />You can also pressure test it per the procedure in the manual. Or get it done at a trustworthy repairer. This will pinpoint where the leak is.
 
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