Honda 30 making oil

[Cascobayboater]

My 2000 model BF30 appears to have an overfilled crankcase. I changed the oil & filter this past spring, adding the correct amount of 5W20. The first few times I checked the oil level, it was good. After about 30 hours of running time, when I pulled the dipstick, oil welled up from the tube. There is no milky white appearance, and no odor of gasoline in the oil.
I confess that the motor is long overdue for a valve adjustment, and the carburetors need to be vacuum synched (erratic idle). This motor sees only intermittent use in the summertime, with 500 total hours on it.This is the first issue I've ever had with it. I have always changed oils (crankcase and lower unit), drained the carbs for winter storage, fogged the cylinders etc. Is the crankcase getting pressurized somehow?

Thanks

 

[JB]

Re: Honda 30 making oil

Howdy, Cbb.

Welcome to iboats.

Check out this article from the Engine FAQs.

http://forums.iboats.com/showthread.php?t=158085

 

[Cascobayboater]

Re: Honda 30 making oil

Hi JB,
Thanks for directing me to the explanation of the 'mystery oil'.
It seems that before I accept this as the cause, I should rule out other problems first, such as leaky fuel pump diaphram, stuck thermostat etc. What other problems could cause the excess oil symptom? I'm not an engine mechanic by trade, though I have some experience from tinkering with stuff over the years. Should I be looking at cylinder compression, valve lash, seals etc? I've never had any smoky exhaust, the spark plugs have always looked good, and when I am running the boat, it's at a full range of throttle speeds. I am turning up to about 5,800-5,900 RPM.

Thanks again,

 

[TOHATSU GURU]

Re: Honda 30 making oil

You need to determine what it is that is adding to your oil volume.

Fuel 98% chance

Water 1% chance

Oil Fairy 1% chance.

No fuel smell = not fuel

No milk = not water

That leaves you with the Oil Fairy

Chances are it is fuel in the oil and the way to eliminate that is to run a thinner oil and not idle as much.

 

[pvanv]

Re: Honda 30 making oil

You need to determine what it is that is adding to your oil volume.

Fuel 98% chance

Water 1% chance

Oil Fairy 1% chance.

No fuel smell = not fuel

No milk = not water

That leaves you with the Oil Fairy

Chances are it is fuel in the oil and the way to eliminate that is to run a thinner oil and not idle as much.

Yep. And don't run synthetic oil.

 

[Packard8]

Re: Honda 30 making oil

Yep. And don't run synthetic oil.

Paul, please enlighten me re no syn oil. Due to low oil operating temps?

(I just changed oil in my MFS 20 and filled w/Valvoline full syn...).

Cheers,

John

 

[pvanv]

Re: Honda 30 making oil

Your Tohatsu (Nissan/Merc/Evinrude) 4-stroke should use NMMA-certified FC-W 10w-30 or -40. If your oil is not rated FC-W, it isn't certified to have the corrosion inhibitors that a 4-stroke outboard needs. Synthetics cost more, may or may not be FC-W rated, and usually promote "making oil".

That said, it will work, just not quite as well as regular dinosaur-based oil.

 

[Packard8]

Re: Honda 30 making oil

Your Tohatsu (Nissan/Merc/Evinrude) 4-stroke should use NMMA-certified FC-W 10w-30 or -40. If your oil is not rated FC-W, it isn't certified to have the corrosion inhibitors that a 4-stroke outboard needs. Synthetics cost more, may or may not be FC-W rated, and usually promote "making oil".

That said, it will work, just not quite as well as regular dinosaur-based oil.

Thanks,

I'll run the fresh fill of syn for a few hours and then switch to the FC-W spec Dino. Another question if you please.... when I recently changed the oil & filter I let it drain for over an hour, both in the tilted and down positions per the manual. Upon refill, it took over 1.5 qts to bring it up to the full mark on the dip stick while the owners manual lists the crankcase capacity @ 1 qt. Would the filter account for .5+ qts? I did start the motor and run it for a few minutes prior to final top off.

Cheers,

John

 

[pvanv]

Re: Honda 30 making oil

The manual says approximately one Liter, not 1 quart. Yes, there is about 1/2 pint or so to fill the filter.

Check your dipstick again; you may have overfilled. It takes some time for the fill oil to register on the dipstick.