1990 force 90hp lower unit leaking oil

[Kalian]

Hey folks,<br />I just noticed a pool of oil underneath my outboard. It looks like it came from the propeller area. The boat has been sitting in the garage for the last 3 weeks. I have been feeling under the weather, and this was the first time I have been in the garage since I took the boat out 3 weeks ago. I don't know if it was leaking when I brought it in, or if it started leaking after.<br /> Does this sound like a reasonably easy (ie, replace some gaskets) thing to fix or is it going to be complicated? I won't be able to get to it until maybe this weekend. I don't have anyone to help me, so if it requires complete disassembly of the lower unit or special tools I won't be able to do it.<br />Thanx in advance!

 

[eurolarva]

Re: 1990 force 90hp lower unit leaking oil

The problem can be from different things. First off smell some of the oil that leaked out. If it smells like gasoline what you are seeing is unburned fuel oil mix that is draining down the leg. If this is the case it is not lower unit related and a different fix will need to be done.<br /><br />If you have determined that the smell is lower unit oil (pretty nasty smell, nothing smells quite like it) the first thing you should do is remove the drain plug and let a little oil come out then re seal it. If the oil is white or water comes out first then oil you have a leak in the lower unit. It could be from faulty seals on the drain and vent plug, the pivot bolt washer is shot. Most likely spot is where the propeller seal is in the bearing cage. Remove the prop and look closely at this seal. Is there fishing line? by slowly cranking motor do you see any oil seeping out there. Another place water can get in is on the drive shaft seal under the water pump.<br /><br />The best thing you can do if the leak is bad is to have the lower unit pressure tested. This is done by putting about 5 PSI of air in the lower unit and submerging it in water or using a water soap combination and looking for bubbles.<br /><br />First verify if this is gas or lower unit oil. If lower unit oil let us know what the oil looks like when you drain a teaspoon or so of it.

 

[Kalian]

Re: 1990 force 90hp lower unit leaking oil

Thanks Euro, now I have an idea of where to start. I can't smell the oil, I have the flu and can't smell anything. It looks really thick, and appears to have large air bubbles in it. It also looks slightly milky. <br /> Would there be an relativly easy way to determine if it's fuel mix besides smelling it?

 

[Kalian]

Re: 1990 force 90hp lower unit leaking oil

As an afterthought, when the boat is sitting in the water,(tied off at the dock) with the cowling off I see water in the leg. The water level inside the leg is equal to water level outside. This is normal right?

 

[Kalian]

Re: 1990 force 90hp lower unit leaking oil

Some more info. I looked closer at it and there appears to be several small holes underneath the fin on both the port and starboars side. Some of these holes definitely had "oil tracks" coming from the hole and running down the lower unit towards the rear, where it dripped onto the ground. Are these "holes" drainage holes? It doesn't look like it's possible for the leaks from the holes to have leaked toward the prop, due to the angle of the lower unit. There are 2 seperate puddles on the ground, it looks like one is from the leaks from the holes in the fin and the other puddle is from the prop area. I'm sorry if this is not clear, I looked through the seloc manual but couldn't find any reference to these holes under the fin.<br /> Also, on closer inspection the oil puddles look like they have water drops in it that probably dropped in the puddles after the puddles were formed. The puddles don't really look milky at all upon closer inspection.<br /> Does it sound like too much pressure built up and blew several seals or gaskets?

 

[eurolarva]

Re: 1990 force 90hp lower unit leaking oil

Those holes you mentioned are exhaust port holes. When the lower unit is in the water the entire leg fills up with water except the gear housing at the very bottom of the lower unit which is sealed. Water goes through the motor and most of it is expelled through the leg and comes out those small holes. Typically when oil is coming out those small holes it is unburned gas and it will look frothy or almost milky white. It will have a strong smell of gas not lower unit oil. The best way to test if you are loosing lower unit oil is to remove the drain plug and let some come out. If it is amber colored it is not leaking. If it is milky white or water comes out then oil you have a leak in the lower unit.<br /><br />If oil in lower unit is fine you may try doing a decarb to help eliminate the excess gas that is not being burned. Other things could be fuel recirculation system not working properly or running too rich.

 

[Kalian]

Re: 1990 force 90hp lower unit leaking oil

Thanks eurolarva, I'll check it tomorow.