I noticed fluid leaking from my motor and suspected it was oil. It wasn't coming from the lower unit. I discovered that when I have my motor titled almost level that oil is leaking out of the oil tank cap and down the sides of the motor. I normally don't have my motor tilted this much but do have it tilted this much when I'm parking my boat (I have a very highly angled driveway) and when I'm putting it in the water.

 

I screwed the cap on as tight as I could and it still leaks. It's a cap where the more you turn it the more a rubber gasket expands similar to a boat plug. I was wondering if a new cap would fix the problem but I'm not sure. It's a 2000 Mercury 115 horse, 2 stroke.

 

 

 

1.)   How can I fix this problem?

 

 

 

2.)   What liquid is the best to clean it up? The oil is all over the inside of the motor and boat motor well. I was thinking hot water and Dawn dish soap but not sure that's the best.

 

 

 

 

 

 

 

 

I have the same motor on my Xpress.

 

1. Don't overfill your oil reservoir - 1/2 is plenty. 

2. Wipe it off with a rag to get the big goobers, then a rag soaked with some degreaser (Perfect Solution, 409, Simple Green) should get the rest. Finish with a damp rag. 

I have the same motor on my Xpress.

1. Don't overfill your oil reservoir - 1/2 is plenty.

2. Wipe it off with a rag to get the big goobers, then a rag soaked with some degreaser (Perfect Solution, 409, Simple Green) should get the rest. Finish with a damp rag.

Will a new oil cap solve the leaking problem or is this model prone to having leaking oil caps?

Won't hurt to try a new cap. I had a 90hp Merc with the same cap but never had a leakage problem no matter how full the oil reservoir was. 

Won't hurt to try a new cap. I had a 90hp Merc with the same cap but never had a leakage problem no matter how full the oil reservoir was. 

 

 

 

 

Can I just get a cap or do I need to get a new O-ring, dipstick, and nut too?

 

 

 

I wonder if I can just get the cap and O-ring and transfer all the old stuff to the new cap and O-ring.

Not sure. I would recommend if you do have to replace the whole thing, is to get the metal dipstick. I've read on more than one occasion about the plastic dipsticks breaking off and falling into the reservoir. 

Will a new oil cap solve the leaking problem or is this model prone to having leaking oil caps?

 

Probably not - the cap is designed to "breath."  Oil expands once the motor reaches operating temps.  If you over fill the reservoir, it's gonna leak. I kept mine around halfway.  Notice the stain on the inside of yours? The previous owner did that too.  I don't think I ever approached using 1/2 a tank of oil in a days boating.

Purple power diluted a little bit is what my auto shop uses.

Hand sanitizer does a pretty good job at removing oil and gunk. 

I had a similar problem with an older mercury that had a similar oil tank configuration. I just kept the reservoir level low enough that it wouldn't leak out when I trimmed the motor all the way up. Whether you replace the cap or lower the oil level you definetely want to do something about it. I ran into a problem where the oil that leaked out was drained down out of the head and down towards the lower unit and got into my impellar and ate it up.(Petroleum and rubber don't mix well) I went through a couple of impellars before I figured out the problem. Definetely something to take care of.

I had a similar problem with an older mercury that had a similar oil tank configuration. I just kept the reservoir level low enough that it wouldn't leak out when I trimmed the motor all the way up. Whether you replace the cap or lower the oil level you definetely want to do something about it. I ran into a problem where the oil that leaked out was drained down out of the head and down towards the lower unit and got into my impellar and ate it up.(Petroleum and rubber don't mix well) I went through a couple of impellars before I figured out the problem. Definetely something to take care of.

Thanks.

Problem solved. It was the oil cap. I replaced it and tilted it fully for 20 mins. No leaking. It used to leak almost immediately. The shop guy said it will leak after 1/2 a day but shouldn't leak before that unless it gets really hot. He said normal tilting shouldn't cause it to leak.

I sprayed everything down with Simple Green and then cleaned it off. Worked well. Thanks for the advice.