excessive oil in exhaust? 40 hp 2 str. Merc.

6/17/14 @ 10:04 AM
ORIGINAL POST
watspan
watspan
USER since 8/3/12
1996 C40ED Merc 40 hp 2 stroke. everything seems to work fine, but after doing lots of trolling I get what seems an excessive amount of milky-white gas/oil globules from the exhaust and from vents on each side of the lower unit just above the cavitation plate. attached video shows condition, however at times it can be worse than shown--thumbnail size globules coming out. normal blow-by or a problem? http://youtu.be/7uSI3NHLlv0
Post Your Comment
Displaying 1 to 8 of 8 Posts
6/18/14 @ 12:24 PM
watspan
watspan
USER since 8/3/12
Thanks for the responses. I think I'll pick up a 4 stroke 4 hp for trolling--better for the lake and I'll save on gas too!

Post Your Comment
6/18/14 @ 10:31 AM
poptop
poptop
USER since 10/1/03
if you do a lot of trolling you could get a spare prop and drop down in pitch this would require higher rpms to maintain trolling speed. of course it would change your holeshot and top speed rpms.

Post Your Comment
6/18/14 @ 9:20 AM
Rifleman1962
Rifleman1962
USER since 4/16/11
What Plmlk said.....That is what is causing the white excessive oil. Open the motor up after trolling and warm it up. It will be gone. Oh'' The. white oil is caused by cooling being not up to the right temp. Running 2 long at idle.

Edited on 6/18/14 9:29 AM
Post Your Comment
6/18/14 @ 8:52 AM
nihsif
nihsif
MEMBER since 6/15/01
unburned oil is an issue if you are running at low rpm's like mentioned

don't know if you pull the boat out of the water, but if you do, the unburned oil drips out and is usually very dark, almost black

as a precaution, I would also take a look at the oil in the lower unit to be sure it isn't milky or low

Post Your Comment
6/17/14 @ 6:33 PM
Plmlk
Plmlk
MEMBER since 12/18/07
That happens frequently to smaller motors that are only used for trolling...

Your motor needs 50:1 at WOT, but could likely get by at 75:1 at idle. When you mix your fuel at 50:1 and don't get above idle speeds all of the oil does not have a chance to burn off, and you see what you are describing...

Every once in a while open her up to WOT.

Post Your Comment
6/17/14 @ 4:47 PM
watspan
watspan
USER since 8/3/12
yes, they would float to the top and burst into a sheen on the surface of the water

Post Your Comment
6/17/14 @ 1:55 PM
crappieguy
crappieguy
USER since 2/11/02
Could be a leaking lower seal on the prop shaft, are these floating to the top of the water?

Post Your Comment