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Author Topic:   lower unit oil seepage
Bertramp posted 05-16-2005 09:55 AM ET (US)   Profile for Bertramp   Send Email to Bertramp  
Replaced the plugs, added fresh fuel, applied the earmuffs, started her up ... and noticed oil in the middle of the prop where the exhaust comes out. I am figuring that I have a lower unit seal issue. yes ? ... how difficult to repair myself ? needless to say all marinas and shops are swamped.
Engine is a 70hp Evinrude ... i think 1994.
bsmotril posted 05-16-2005 10:27 AM ET (US)     Profile for bsmotril  Send Email to bsmotril     
More than likely, that is oil residue from the exhaust, and not the seal leaking. Pull the prop off, and thrust washer (if your motor has one), and visually inspect the seal. If there is no fishing line around it, and it looks normal, it is most likley OK. It is normal for two strokes to drip or seap oil out of the exhaust housing. BillS
LHG posted 05-16-2005 12:13 PM ET (US)     Profile for LHG    
Black, thick oil/goo coming from the exhaust is often related to a too rich carb setting, and also seems to be DEFINITELY related to alcohol fuel, made even worse by some of the reformulated big city anti-pollution additives.

My carbureted Mercury's run best and cleanest by far, on pure gasoline. But it seems the only place to get it these days is in Canada.

lloyd13 posted 05-16-2005 04:27 PM ET (US)     Profile for lloyd13  Send Email to lloyd13     
Canada is the answer for several boating items. One I learned years ago when I had an Origo stove and oven. Alcohol. Their alcohol burns clean and pretty dry. The junk you buy in the US has to be half water.
Bertramp posted 05-16-2005 05:04 PM ET (US)     Profile for Bertramp  Send Email to Bertramp     
well ... you folks definitely lowered my blood pressure.
I'll give the seal a look myself and then run sparingly until I can get her checked out professionally.
Fingers are crossed.
Joe Kriz posted 05-16-2005 05:37 PM ET (US)     Profile for Joe Kriz  Send Email to Joe Kriz     

I owned a 1985 Evinrude 70hp for 15 years. The only thing I ever had done to that motor was the lower prop seal.

My boat sits in the garage. One day I went out and saw a small puddle of clean yellow oil. Not good. I knew it was not left over exhast and/or mixed fuel and oil drippings, definitely lower end fluid.

I took it to my Evinrude mechanic. He did a pressure test and a vaccum test. Both test passed. OK, then where is this clean yellow oil coming from?

I had the mechanic do the lower prop seals anyway. Got it home and it never leaked a drop.

Just goes to show you that not all these tests will always find the problem.
Apparently with pressure the leak sealed itself. The leak also sealed itself with the vaccum test. But with no pressure or vaccum, the lube oil leaked out passed the seals and onto my clean garage floor.

Anyway, you need to determine if it is left over oil/fuel mixed in with the exhaust or if it is clean (yellowish) lower gear oil leaking out as several have already mentioned above.

scaleplane posted 05-18-2005 01:08 PM ET (US)     Profile for scaleplane  Send Email to scaleplane     

The day after I ran my 40HP Johnson on earmuffs after a long Winter's nap, I also noticed what looked like oil on the housing around the prop. I was concerned, but after wiping it off and checking back later, I've had no additional stains. The boat's in the water now (for the Summer), and I don't notice any oil marks, so I'm making the assumption that the oil that came out was a result of my excess winterizing lube being pushed out the exhaust.

Legobusier posted 05-18-2005 01:42 PM ET (US)     Profile for Legobusier  Send Email to Legobusier     
Just goes to show you that not all these tests will always find the problem. Apparently with pressure the leak sealed itself. The leak also sealed itself with the vaccum test. But with no pressure or vaccum, the lube oil leaked out passed the seals and onto my clean garage floor.

I had the same exact thing happen on my lower unit last year. Oil was leaking, pressure tests came back normal. Then based on Chuck Tribolet's suggestion (thanks again Chuck) I pressure tested AGAIN, this time with only 3 or 4 psi and it leaked. Like you said Joe, the pressure pushed the seals into place.

Moral of the story is pressure test with low pressures.


Chuck Tribolet posted 07-26-2006 12:30 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
My engine is a '97ish Evinrude carbed 2-stroke 90HP.

I found a 5" puddle of thick black oil under the prop this
week. I drained the lower unit (it's about due anyway)
and the lower unit oil was clean and green and thinner.

5" diameter puddle seems like a LOT, but I also recall that
this puddling phenomenon is related to idling, and this weekend
we did nothing but idle, for about two hours.

Any thoughts?


pglein posted 07-26-2006 05:43 PM ET (US)     Profile for pglein  Send Email to pglein     
Simple solution: Check your lower unit lube level regularly. Change it yearly.

Cheap insurance.

Stevebaz posted 07-27-2006 06:51 PM ET (US)     Profile for Stevebaz  Send Email to Stevebaz     
I had my stroke last month with this issue. Old boat new to me but the first time I used it ever I took it out for an all day boat cruise around Newport Harbor CA. This is my first boat so I get to worry about everything that I dont have experience with. Got home and the next morning a black sluge puddle the size of an orange on the ground under the prop. That gave me the OH shitz for a week trying to find seal parts for the old motor. Found this very helpful website.
This explained the black sluge issue and I crossed my fingers and pulled the prop and the sluge was comming down the exhaust ports and not from the shaft seal. Boy was I relieved. Lugging the engine all day using winterized gas and the engine not run in several years and to top it off I used Chevron gas with its superior cleaning ability to top off the tank. This all contributed to excessive oily sluge. So dont panic just yet.
Chuck Tribolet posted 07-28-2006 06:25 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
I never paniced. I was pretty sure that's what it was and
was looking for some reassurance. Thanks for the idea of
looking into the exhaust passages -- I didn't even need to
pull the prop or get a flashlight to see that there was
lots of the same tar back up in the exhast passages.

BTW, I have to store the boat with the motor tipped down in
order to close the garage door. I suspect that if you store
it tipped up a bit, the tar just accumulates in the angle
and doesn't drip out.

Plus it was hotter than hades last Sunday when I didn't run
the boat (109F at my house, reports as high as 118F around
town), and that probably didn't help.

Anyway, lower unit has fresh oil, and EverRude is ready to
go tomorrow.

Thanx all


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