150 hp, lower Unit Leaking gear oil out vent hole

22trophy

Seaman
Joined
Aug 2, 2003
Messages
54
My 2001 150 hp leaks gear oil out the vent hole. It leaks out the hole adjacent to the oil screw fill hole. Freshly filled 25 hours ago. This occurs after running the engine on the garden hose, and in gear at low idle. Any suggestions on how to stop the gear oil from leaking out this vent hole would be geatly appreciated!
Thanx
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 150 hp, lower Unit Leaking gear oil out vent hole

Remove lower unit.
Drain gear lube.
Then do a pressure check of the lower unit and determine what is leaking.
 

Strength454

Cadet
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Jul 26, 2010
Messages
10
Re: 150 hp, lower Unit Leaking gear oil out vent hole

What is pictured is a 1977 johnsosn 85 hp, I like to start it once a week to keep the batteries & everything else in check When running w/the earmuffs everything seems ok, when I stop the motor & the water drains a mix of oil & water seep out of the weephole(top) as shown in pic, I recently had the water pump replaced, and lower unit oil replaced, have only had it out twice since then...Is this going to be a seriuos problem?? any help would greatly be appreciated....
 

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joed

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Sep 28, 2002
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1,132
Re: 150 hp, lower Unit Leaking gear oil out vent hole

There are NO vent holes in the lower unit. The oil would leak out ( and water leak in)under operating conditions. That is some other vent hole. The oil is likely unburnt fuel.
 

carholme

Rear Admiral
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Sep 4, 2010
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4,845
Re: 150 hp, lower Unit Leaking gear oil out vent hole

On both engines mentioned above, the vent holes are there to drain any trapped water. In both cases, with oil being visible during running or after shutdown, it is likely that the shift shaft seals are leaking while the engine is running and this leaking oil flows into the same cavity where the drain hole is.

A second possibility is the Main Drive shaft oil seals under the water pump.

If you drop the lower units after running you should be able to see water and oil mix remaining in the deep cavity surrounding the shift shaft and you will probably see an oily residue on top of the shift shaft seal holder.

You can pressure test them in a water tank to see for sure which one is leaking.

carholme
 

Strength454

Cadet
Joined
Jul 26, 2010
Messages
10
Re: 150 hp, lower Unit Leaking gear oil out vent hole

Thanx Guys, i just had the lower unit oil changed, and water pump kit changed, before then I had no problems, now im leaking, maybe it was not properley re-installed...back to the mechanic, I will update after holidayz......
 
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