Oil behind prop on 30 hp evinrude

[MAKO72]

I recently noticed some oil dripping from behind the prop on my 1989 30hp evinrude. I removed the prop and ran the motor. When I stoped the motor I could see that it was dripping down from the exhaust hole. The motor runs fine I was just wondering if this was normal or is their a bad seal somewhere? Thanks for any help.

 

[robertmcp72]

Re: Oil behind prop on 30 hp evinrude

my evinrude 9.9 does the same thing.<br />more than likely it's oil residue from your fuel mix.Is it black? or yellow in color?

 

[mountainboy]

Re: Oil behind prop on 30 hp evinrude

My evinrude 9.9 does the same thing. I thought that is a seal problem, but never thought it would be oil residue. After a day of fishing it usually drips then slows then stops. The oil is a black color. MB

 

[mountainboy]

Re: Oil behind prop on 30 hp evinrude

Is it ok to have oil residue drips from the fuel mixture? What does this mean exactly? Thanks MB

 

[Down South]

Re: Oil behind prop on 30 hp evinrude

Hi MB,<br /> They are talking about unburned two cycle oil dripping out of the exhaust around the prop. It's not uncommon nor is it a problem. The unburned oil is a dark sooty color. If you notice a clear or milky oil in this area it may be lower unit oil and needs to be investigated.

 

[MAKO72]

Re: Oil behind prop on 30 hp evinrude

Thanks for the replies but the oil I'm seeing is a grayish (milky) color not like the black oil that drips from the little hole by the cavitation plate. I checked the lower unit oil and there was no water the oil was full and it was clean. Any other suggestions thank you.

 

[Down South]

Re: Oil behind prop on 30 hp evinrude

Highlines,<br /> The only two places that you can get oil from is the lower unit or unburned two cycle oil. If you have checked out the lower unit then you've eliminated a leak there. What your seeing is probably just the unburned two cycle oil mixed with water.

 

[MAKO72]

Re: Oil behind prop on 30 hp evinrude

I ran the motor in the driveway again and now I see that the oil that used to seep out of the little hole by the cavitation is also gray or milky this oil used to always be very black. I think I might have water leaking into the cylinder(s). Any ideas suggestions thank you. I also checked the compression and the top cylinder was about 5-10 lbs. less than the bottom. Could it be a head gasket can water enter somewhere else? Thanks

 

[DJ]

Re: Oil behind prop on 30 hp evinrude

high lines,<br /><br />What do the spark plugs look like? Are they real clean almost new looking?

 

[MAKO72]

Re: Oil behind prop on 30 hp evinrude

The spark plugs were pretty clean not completely but I guess cleaner than usual I did notice they were wet but it smelled like gas. If it was the head gasket could I remove the head without taking the whole powerhead off. Are there any tests I could do to help determine the cause. Thanks for the help.

 

[DJ]

Re: Oil behind prop on 30 hp evinrude

highlines,<br /><br />If the plugs are clean it is a sign of water ingestion. Yes, you can remove the head without removing the powerhead. It is quite simple actually.<br /><br />The spark plug appearance is really about the only test.

 

[MAKO72]

Re: Oil behind prop on 30 hp evinrude

With the head removed can you usually tell if water has entered? What should I look for in terms of damage etc. Do I need to take the head to a shop to be checked out. I appreciate the help.

 

[DJ]

Re: Oil behind prop on 30 hp evinrude

highlines,<br /><br />About the only thing you will notice is that everything will look really clean.<br /><br />More than likely a new gasket will fix you up.

 

[MAKO72]

Re: Oil behind prop on 30 hp evinrude

djohns19,<br /> I removed the head and you were right the top cylinder was totally clean the bottom one looked normal. I couldn't notice any damage to the gasket that would indicate water leaking but hopefully that is the cause. Is there any other way water could be entering that cylinder? Thanks again for your help. I also noticed my thermostat was stuck open I'll also be replacing that.

 

[MAKO72]

Re: Oil behind prop on 30 hp evinrude

To check if the cylinder head I removed was not warped I put it on a pane of glass the head seemed to rock just slightly. Is it possible to sand it down some or should I just take it to a shop and what would that cost. Thanks.

 

[Cornell]

Re: Oil behind prop on 30 hp evinrude

I thought you might find this report I read in the forum very interesting. Maybe you already had it sent to you, if not here you are. I had the same problem with my 15hp. I used Seafoam and 90% of the problem went away. Spray in carb for about 10 seconds at fast idle so it doesn't kill. Then spray in cylinders, put plugs back in. Wait for a few hours. Start up and let smoke clear run to hot. You can do this twice and it should be cleared out. Motor now shouldn't leave excess oil in lake water but may seep some grease slightly out of prop exhaust area which I hear is normal. My problem was the grease came out of the 3 exhaust ports.
Cornell

Oil leaking around the lower unit

So, you have oil leaking out of, or around the lower unit on your two-stroke outboard and you?re wondering what to make of it all. There?s only a few possibilities. Fortunately for you, most of the time it?s pretty benign.

Reason #1 - Unburned 2-stroke oil.
This is by far the #1 reason for finding oil on your lower unit. 2-stroke outboards use a mixture of oil and gas. Not all of the fuel gets completely burned up. As a result, not all of the oil gets completely burned up either. Since gas is more volatile, it has a tendency to evaporate away, leaving just the oil or at the very least, a more concentrated gas-oil mixture. Combustion is even more incomplete at low RPM. What are you doing right before you put your boat on the trailer? Motoring around in the no wake zone and building up unburned oil.

Unburned oil will normally be black and sooty. However, if there?s a lot of it (and this can happen when purging out all that fogging oil from winterizing) it can look amazingly like old lower unit lube.

Normal places to see unburned oil are out the prop, out the top of the lower unit, and through some of the water drain holes in the lower unit. To add to the confusion, these are also normal places to see leaks due to Reason #2. If you?re not sure what the source is, inspect the lower unit oil as described later. If you find no water intrusion in the gearcase you?re most likely looking at unburned 2-stroke oil.

Seeing unburned oil is fairly common and perfectly normal. It does not in and of itself point to anything wrong with your outboard.

#2 is description of gear housing lower end. If it is clean then you are OK. If not email me or find the article I just gave you, if you don't already have it. Good luck