Billowing smoke from 2004 Honda BF20

sparky77

Recruit
Joined
Jan 28, 2005
Messages
2
I recently changed the oil in a 2004 honda BF20 after 20 hrs of use (motor is new). After 15 min of running at full throttle, the engine started billowing white smoke out of the idle exhaust port and also the prop exhaust and cavitation plate exhaust. The green oil light and water stream were still ok. When stopped and tilted the motor up to investigate, I noticed an excessive amount of oil leaking out of the airbox overflow drain and down all over the lower unit. Also, there were new black oil stains around the prop exhaust and caviation plate exhaust. These stains were black, burned oil. The oil leaking out of the airbox was clean. <br />Of course, when I took the motor to the shop, there was no smoke, and the mechanic said it was "tilting the motor up" that causes this problem by having oil leak into the carburetor. But that doesn't explain the fact that this motor had not been tilted since before the oil change, and the smoke/leak did not start until after 15 min of full throttle running. As well, the motor was previously kept tilted up as the boat is moored, without any problems. <br />The oil change was conducted exactly as per the honda manual - oil allowed to drain and refilled with exactly 1 litre of oil (as specified when oil filter not replaced). The oil level was checked correct prior to running. <br />The shop thinks there is no problem with this motor... any advice/comments would be appreciated as I don't know what caused this problem.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Billowing smoke from 2004 Honda BF20

wow you must have ordered it with the skeeter fogging option.<br /> actually it could have been slightly over filled. if so the excess is called blowby. its when the crankcase pressure forces the excess oil into the airbox through the crankcase breather system and is drawn into the carb on the intake stroke.<br /> so keep an eye on the level and see if it happens again.
 

sparky77

Recruit
Joined
Jan 28, 2005
Messages
2
Re: Billowing smoke from 2004 Honda BF20

Thanks for the quick response. <br />I guess it could have been overfilled, but that seems unlikely as I was very careful about the oil level. <br />If that was the problem, is the engine damaged now?
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Billowing smoke from 2004 Honda BF20

most likely not<br /> as long as so much oil does not get into a cyl and cause a hydrostatic lock. <br /> so I would say keep an eye on the oil level and try not to fill it to the max mark. I would rather see the level about 1/2 way up.
 

eipeldau

Seaman Apprentice
Joined
May 11, 2007
Messages
49
Re: Billowing smoke from 2004 Honda BF20

I have the exact same outboard as yours and just happened to perform myself the 20-hour maintenance service yesterday.
I let the HOT oil drip for around 15minutes and then filled with around 850ml of new oil. This put the oil level to around 80% of the dipstick's marks range. Here comes the tricky part: Our engine has a terrible dipstick. When you're pulling out, it gets "contamined" by the oil on the inside of the tube. So it's pretty hard for you to accurately assess the oil level. The solution I found for this was: Warm up the engine, turn it off and remove the dipstick. Wait until the engine cools down. Now the oil on the inside of the dipstick's tube will have flown down and won't contaminate the dispstick. You can now take ONE accurate measurement with the dipstick.
I believe you probably had too much oil in, likethe others said.
 
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