gray/black oil under outboard pan

[tinboatman]

Hello everybody I have been continuing fixing up my old 1972 25 johnson. I noticed about 2 weeks ago a bunch of tacky gray and black oil gathering up where the midsection meets the pan and was starting to leak onto the midsection. After that I pressure washed it all off and after only a few hours of running its all back. What I am wondering is what can cause this and could this be why my idle is still not 100% correct even after I fixed the spark issue. I am providing some pictures of the oil to this post.

 

[kevinj]

A couple quick possibilities:
1) Exhaust cover gaskets are bad: https://www.marineengine.com/newparts/part_search.php?part_num=316162
2) Exhaust Baffle gasket is bad: https://www.marineengine.com/newparts/part_details.php?pnum=OMC0314421

With the engine hood removed run the engine at idle in a barrel or on the lake. Look around the exhaust cover and base gasket where the engine block meets the mid-section for exhaust or water coming out.

 

[tinboatman]

How do I tell if exhaust is coming out do I put my hand near it and see if a I feel it? Il try to get it in the water tomorrow to find out. Thanks for the info!

 

[kevinj]

You should see a little blue smoke around the gasket if it's leaking. You could also make up a small tank of fuel at 25:1 or even 16:1 so it's overly rich with oil. That should cause a lot more smoke and make it easier to see. Also, try getting the water a little high so that the exhaust relief port is under water. This will cause backpressure and if there's a leak will help to ID the location.

KJ

 

[tinboatman]

Sorry I havent tested the motor yet, I am waiting for a fuel pump rebuilt kit to arrive because the pump was pumping air with the fuel and had a leak. I was wondering if the oil I am seeing could have been coming from the carb due to gas leaking out when I tilt the motor up because I keep the boat pulled up on shore. I was wondering this because I have not seen any noticeable performance loss at WOT with the hood on vs it off and generally from my research when there is a exhaust leak it causes the performance to drop significantly from the carb not getting enough fresh air.