BF 225 Counsuming oil

"I have a 2006 BF225 that is c

"I have a 2006 BF225 that is counsuming about a 1/2 quart of oil on a 3 hour trip. There is no visible smoke, spark plugs look fine, no visable leaks or oil in the water. Can anyone tell me how this is happening?

Tom"

"How many hours on that engine

"How many hours on that engine? How do you use it?

I assume you have inspected the bottom of the lower cowling for any oil setting in there. If not, do so. That would indicate an external oil leak somewhere.

1. Check the oil in your lower unit. If motor oil is in it (it will float to the top after sitting for awhile) you likely have a leaky or blown main seal.
2. Your rings may not be seating in one or more cylinders. Do a compression test on each cylinder. If you do a lot of trolling and don't run enough at WOT, the rings may not seat properly.
3. One or more valve stem seals could be leaking. However, that should show up as black soot on at least one of the plugs.
4. You could have a blown head gasket. But that would usually show up as an oil slick in the discharge water, unless it is pushing oil into one of the cylinders. If so, there should be a foued spark plug.

If you eliminate that there is a problem with oil getting into the lower unit, you may want to try a decarbonizer like Yamalub Ring Free or Sea Foam and see if that clears up the problem. Be sure to do a complete and thorough oil change after decarbonizing. Then carfully monitor oil consumption."

Re: "How many hours on that engine

I'm a OMC guy and know their 2 stroke now I have 2 bf225 and was wondering how oil gets from the motor to the gearcase. I can't see how it can get there.

Motor oil can not get into the gearcase -----they are sealed units !!!!!!!!-----------------If it does , then there are bigger problems I would say.

What was chawkman talking about in #1 above?Did I misunderstand what he was saying?

Tomtemp was losing oil - 1/2 quart on a three hour run. I was trying to give him some diagnostics. Bottom line, initially I would decarbon engine to see if that helped. If not, then run a compression and leak down test. If that doesn't uncover the problem, then it's time for a bug hunt - the oil is going someplace.

Hi chawk_man--I think your suggestion that Tomtemp check out the lower unit for oil might have been confusing. I'm presuming that engine oil would never be found mixed with gear oil--are we missing something in your diagnostic recommendations? thanks

Correct me if I'm wrong chawk_man but I interpreted what you said to mean that the main shaft seal could be puking oil, it's running down the shaft and pouring on top of the gear case in the lower unit. Not in it.

Totally plausible and might match tomtemp937's description of "no visible leaks or oil in the water" because it is most likely occurring at higher shaft speeds so it would be pretty much washed away when stopped. You might see something if you ran it dockside at high rpm for an extended amount of time but even then, with exhaust turbulence and bubbling, it still might be fairly hard to detect.

If that is what is happening it should be readily evident if you pulled the gear case and inspected the shaft, the inside of the extension and the top of the water pump housing.

Jimmy,

You are absolutely correct.

Do four strokes really ever need "Decarbonizing"...auto engines can run for hundreds of thousand miles and still have excellent compression...are marine engines any different in this respect?

Yes, four strokes can and do benefit from decarbonizing. Gasoline is a hydrocarbon hence carbon and water are residue byproducts of combustion. It's just that the water vaporizes and doesn't really hang around but the carbon deposits will adhere to the valves, pistons, rings and cylinder heads.

Outboards ARE different in that they are typically used considerably different from automobile engines. An outboard may experience many hours of low throttle, low load operation when the boater is fishing and this can lead to carbon build up in the cylinders due to the lowered combustion temperatures that the engine will experience. Poor cooling system maintenance resulting in stuck open thermostats is also a culprit in lowered operating temperatures and poor combustion. This can lead to carbon deposit buildup in ANY gaseous fueled internal combustion engine including diesel, propane and natural gas.

Additionally, outboards are routinely operated at much higher rpm when traveling from port to fishing ground or for pleasure. The average car engine is usually subjected to no more than 3,000-4,000 rpm during normal driving and cruise. Outboards, on the other hand, are routinely subjected to 5,000 to 6,000rpm full throttle operation.

The bottom line is that results will vary from one guy to the next guy based on how well he maintains his equipment and how gently or harshly it gets used.