New to boats and have a problem. Oil leak

mark reinwald

New Member
Aug 23, 2022
13
Boat Info
1983 Sea Ray Seville 120
Engines
Mercruiser 2.5
I have a 1983 sea ray Seville 120. It has a mercruiser 2.5 with an alpha drive. It’s in great condition and well taken care of. Just started getting oil in my bilge and it’s coming though the drive shaft (sorry if my terminology is off). So if my research is correct then my Stern drive seal is leaking?
min going to pull it out of the water and check the bellows and see if they are full of oil. Then check the oil in the lower unit. I think this is the right direction but please point me in the right direction if I’m off about something. Thanks!
 
If it is engine oil, which is the most likely to be found in the bilge, then there are multiple area's to investigate. The typical engine oil leaks are the valve covers, the oil pan, and the main seal at the rear around the crankshaft.

Oil from the outdrive is not likely to get to the bilge. I don'r see a path for that.
 
Clean the bilge and dry it out then place a drip towel under the motor. Prime areas would be the timing chain cover, rear main seal, oil cooler lines / remote oil filter / or the filter itself. Run the girl then check those pads. This will give you an idea as to where to start
 
I checked it out and took a picture. It’s coming in at the shaft that gos to the out drive. I checked the seal on the motor and it’s dry. Didn’t try the oil mat yet but it’s definitely a good idea. I’m thinking my best bet is to get it out of the water. Aside from the oil coming through the shaft it’s all clean and free of oil.
 

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Well it’s dirty so it looks blackish brown. My motor oil on the dipstick is new looking.
 
It's most likely grease from his gimbal bearing. Odds are its overgreased which just means it'll be messy. Either that or the bellows are leaking and water is getting mixed with the gimbal bearing grease long enough for it to dribble down the back into the bilge and make a mess.
 
Its probably grease. I love those little 4 bangers. Run for ever. I miss mine.
+1 on that. I had an 1984 19’ Seville and it ran like a scared rabbit, trimmed out with two people she’d hit 43mph. Bought her new and had her in the family for 22 years. My daughter told me I sold her childhood when I let her go. Lol, missing her as well. The boat that is….
Good luck with her, they are about as simple as they come as far as working on.
 
I checked it out and took a picture. It’s coming in at the shaft that gos to the out drive. I checked the seal on the motor and it’s dry. Didn’t try the oil mat yet but it’s definitely a good idea. I’m thinking my best bet is to get it out of the water. Aside from the oil coming through the shaft it’s all clean and free of oil.

How did you check the crankshaft seal?

I agree with the others, if it's not engine oil then it's *probably* grease from the gimbal bearing / u-joint. Have you serviced this area lately? If not I'd guess you have a small bellows leak and what you are seeing is dirty water and grease. If you have serviced it perhaps it was over greased.
 
'Sounds like you're needing to pull the outdrive to make sure you don't have a leak in the bellows. A leak there can make your u-joints and gimbal bearing go away really fast!
 
Lay across the engine and stick your finger in the blob of brown stuff. Then you will know if it's just excess grease from an overly lubricated / greased bearing or input shaft, or if it's oil and such.

If it's drive oil. it will stink like regular gear oil.
 
Well…. I have a bigger problem. So the oil I’m sure is somekind of motor oil. The out drive is fine. I checked the oil today and it’s milky. I’ve checked this multiple times this season and it was good. So my bigger problem is this. I’m all over the googles trying to find reasons for this, but it’s probably not good.
 
Well…. I have a bigger problem. So the oil I’m sure is somekind of motor oil. The out drive is fine. I checked the oil today and it’s milky. I’ve checked this multiple times this season and it was good. So my bigger problem is this. I’m all over the googles trying to find reasons for this, but it’s probably not good.

If the oil inside the engine is milky, stop running it immediately. More than likely the head gasket has failed. It's not as hard of a task as you would think to fix. Get yourself the proper SELOC repair manual for your motor and get er done. If you keep running it like that you may need a whole new motor.
 
Well…. I have a bigger problem. So the oil I’m sure is somekind of motor oil. The out drive is fine. I checked the oil today and it’s milky. I’ve checked this multiple times this season and it was good. So my bigger problem is this. I’m all over the googles trying to find reasons for this, but it’s probably not good.

You may have two different problems as water in the oil is not generally going to be the cause of your first problem. It happens, and can be from a number of things. Everything from head gaskets to cracked head/block, and points in between :)
 
If it's any consolation, the 2.5 is a piece of cake to work on / pull out if need be. Don't get all worked up yet. Very 1st thing to do is get the milky oil out and refill w/ clean oil and filter and get that circulated.

Just start trouble shooting and find where it's coming from. I would start by getting the cooling system pressure tested to see if it's coming from the water jacket (warped or cracked block or head), 1st. 2nd would be a compression test to see if there is an obviously blown head gasket.

The oil in the water is a big issue, but can be caused from a multitude of things, such as a cracked block or head, a bad exhaust manifold, a bad head gasket, water coming back in the exhaust and down through the exhaust valves or even as something as simple as getting water in the carb from rain / bad engine hatch. If those little engines are overheated, they like to blow out the head gasket / warp the head.

I would acquire a Mercruiser service manual (can be found online). The ones like the Seloc are ok for generalizations, but can leave something to be desired when getting down to granular details.
 
Anyone have a walk through on how to pressure test the cooling system? I’m very familiar with cars so I have an understanding of the motor.
 

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