Gas in Oil F250

[captain rednut]

Fuel Dilution

Here in Australia we have encountered a Lot of F250 and F300 models experiencing very high levels of fuel dilution in there oil, in most boats that are experiencing the problem they all do a lot of idling/*****ing and there oil only lasts 50 hrs including my very own engine.
Cheers Jim

[rodbolt17]

oneday outboards may have closed cooling.
until then extended periods of low speed operation will not allow everything to stay at a decent operating temp.
this leads to fuel dilution.

once you rule out any rare mechanical issue look at maint issues and run pattern issues.

that motor MUST run 4000 RPM or above for the last 20-30 mins of trip time.

I had a cust complaint a few years back on making oil.
run history showed about 325 hours with over 300 below 1000 RPM.
from the mans dock to the old manns harbor bridge was about a 2 min run for him.
the next 4-6 hrs are spent *****ing the bridge in water between about 50*F and 40*F.

I explained to him that when done fishing he MUST run it above 4000 RPM for at least 20 min to clear the oil.

while outboard manufactures have spent millions in research and EPA compliance to make these motors start and operate similar to your auto they are NOT automotive.

[Nautical]

One more thought.. Make sure thermostat are working. Condensation build up may fool you by increasing oil level .

[Gunnar00]

There must be a better way...

This kinda looks to me like a "one seise fits all" thing gone wrong...

Both boats that we have delivered here in Iceland with twin Yamaha 4.2L F250 are having massive oil dilution issues and the north atlantic ocean does not always allow us to run 20min WOT (40kts) so

How about swapping out the thermostats for hotter ones for us in the 40 deg F waters?

I guess Having 1 liter less oil in the sump enables the engine to run hotter oil temps, but can you go lower?



Regards, Gunnar

[boscoe99]

This kinda looks to me like a "one seise fits all" thing gone wrong...

Both boats that we have delivered here in Iceland with twin Yamaha 4.2L F250 are having massive oil dilution issues and the north atlantic ocean does not always allow us to run 20min WOT (40kts) so

How about swapping out the thermostats for hotter ones for us in the 40 deg F waters?

I guess Having 1 liter less oil in the sump enables the engine to run hotter oil temps, but can you go lower?

Regards, Gunnar

One size never has and never will be all things to all people. Which is why even in my automobile owner's manual there are different maintenance schedules for different ways of operating the vehicle.

In some Yams they (Yam USA) did suggest using a thermostat with a higher opening temperature. Have not heard that as a suggestion for the bigger HP Yams. You could certainly try it to see if the situation improves.

In a good working oil system I don't see having a quart less oil as having any appreciable (or any) effect on the oil temperature.

The biggest contributor that I see relative to Yamaha outboard motors and their propensity to "make oil", aka fuel in oil dilution, is that Yamaha does not specify a break in procedure that will facilitate the seating of the piston rings. Mercury Marine does. If one follows the Mercury Verado procedure the chances of the rings seating in a Yamaha (and seating sooner than they otherwise might do) will be greatly improved. We hear quite a bit about fuel in oil with respect to Yamaha four strokes. We almost never hear anything at all about a Verado with this problem.

Now is Yamaha ever going to agree that some other engine makers procedures might be a bit better than their own? Won't happen. Particularly with the Japs.

Another possibility for those Yamaha's that have a water/oil heat exchanger is to bypass the water around the heat exchanger to see if the oil temperatures can be increased a bit if one is operating in extremely cold water and one cannot run the motor at a power setting that will get the oil temperature up to snuff.

I once put a temperature sender in an oil drain plug to see what sort of oil temperature I saw on an F150. The oil ran extremely cold.

[zenoahphobic]

Making oil/using oil

This makes one think that design certainly has not kept up with performance increases achieved over the years.

Logic should suggest the oil behind the piston should go past the rings as it does get there through gravity. And the meeting of more environmental standards leading to greater fuel efficiency and engine management systems would suggest that the engine should limit what fuel goes past the rings. Because of the making of oil, eventually the excess unburnt fuel (and oil) must blow out into the environment.
How did Yamaha ever convince authorities that these engines meet emission standards? Did they collude with VW and fudge the figures?
I would never want to have one of these poorly designed engines.

[99yam40]

This makes one think that design certainly has not kept up with performance increases achieved over the years.

Logic should suggest the oil behind the piston should go past the rings as it does get there through gravity. And the meeting of more environmental standards leading to greater fuel efficiency and engine management systems would suggest that the engine should limit what fuel goes past the rings. Because of the making of oil, eventually the excess unburnt fuel (and oil) must blow out into the environment.
How did Yamaha ever convince authorities that these engines meet emission standards? Did they collude with VW and fudge the figures?
I would never want to have one of these poorly designed engines.

If you dislike these Yamaha's so much why are you even here posting on a Yamaha forum?

[boscoe99]

This makes one think that design certainly has not kept up with performance increases achieved over the years.

Logic should suggest the oil behind the piston should go past the rings as it does get there through gravity. And the meeting of more environmental standards leading to greater fuel efficiency and engine management systems would suggest that the engine should limit what fuel goes past the rings. Because of the making of oil, eventually the excess unburnt fuel (and oil) must blow out into the environment.
How did Yamaha ever convince authorities that these engines meet emission standards? Did they collude with VW and fudge the figures?
I would never want to have one of these poorly designed engines.

What poorly designed engine are you speaking of? Honda, Suzuki, Tohatsu, Yamaha, Mercury or ??? They all (four strokes that is) can "make oil" depending upon the state of break in and the manner in which they are used. Condition of the thermostat and type of propeller can also effect this anomaly.

[zenoahphobic]

99Yamaha and Boscoe,
It stands to reason that there seems to be problems with these engines by what has been said about them.

If I were an engine designer I would need to go back to the drawing board because the conditions mentioned will become eventual unacceptable to the buying public- it was suggested Verado did not have anywhere near this "oil making " problem.

It is sort of like very early ignition systems (a burning candle!) worked to make the engine run but often lead to the engine incinerating , consumer pressure eventually leading to the invention of an electric ignition system.

If I saw as a problem of oil behind the piston, or the oil was to cold, or whatever, I would focus on research to invent something that solved the problem. It was suggested the engine was not "hot" enough, for goodness sake that problem was solved 100 years ago, so why does Yamaha (or others?) persist with a pathetic cooling design- as another example.

I don't dislike Yamaha, but their 4st outboards appear to let the brand down.

[boscoe99]

If an automobile with a four stroke motor is idled quite a bit the oil will get contaminated sooner than it otherwise might. Thus the reason the manufacturers recommending more frequent oil changes. Same with idling a four stroke outboard. It is severe duty. Oil will need to be changed more frequently. Say when the oil pan goes over the fill mark due to fuel in oil dilution.

The four stroke Yams are there most popular models. Hundreds of thousands of the buggers being sold. They probably sell more than all of the other brands put together. One reason that we read more about Yams with the making oil issue. If one sells four times the number of motors it is reasonable to read about the problem being stated four times as often.

Aluminum blocks and heads being used in salt water don't lend themselves to being operated at the temperatures that aluminum blocks and heads with a closed circuit cooling system using corrosion resistant coolants can.

The craftsmanship of Yamaha is superb.

The engineering of Yamaha is acceptable. About on par with the other brands. All four strokes suffer from making oil.

Where Yamaha really lets the customer down is with respect to their data. Their owners manuals. Their service manuals. They shoot themselves in their feet with their four stroke break in procedure. They spends tens of thousands of dollars helping customers with the making oil issue when with the stroke of a pen they could prevent a number of those issues from arising in the first place. Strange.

Call Yamaha USA and get a technician on the line and to a man they will tell you to run the shit out of a four stroke from the get go. Don't let it idle they will say. Power is needed to seat the piston rings. Unfortunately most users are never going to call Yamaha USA. They will read the owners manual. They might then suffer from making oil.

[zenoahphobic]

In fairness to engines that "make oil" some fuel always went past the piston rings with all combustion engines since the dawn of time. But the volume of oil increase was always lesser than the oil that was lost going past the rings out through the valves. That is, for many decades oil levels always dropped and was added regularly at fuel station stops ("fill 'er up and add a pint of oil too please").

It is therefore become an issue as oil going past the rings has been dramatically reduced (suspect by manufacturers being pressured to meeting hydrocarbon emission standards).

The future has to be closed coolant with a heat exchanger. In essence this would not actually add much weight to the boat (or transom) when it is in the water! Other than developmental costs, the cost to manufacture must be little also. But we have to wait to see who will break away from the "collusion" between O/B makers.

And obviously more work needs to be done to get these piston rings to seal better under lower combustion pressures. Ridiculous really, piston rings and piston groove design has been done to death.

Lastly, I question whether seating rings by driving hard actually would have any great affect, as it would raise the temp of the ring higher than it would be in normal service, expanding it and therefore wearing it distorting the actual mating contact surfaces. Not to mention, this procedure does nothing but deteriorate the "seal" between the piston groove top and bottom surfaces!

Cars do not need this breaking in and go for many many miles without issue (including all those horizontal cylinder cars (VW, Subaru etc)), so why is it that O/B apparently need all these particular procedures mentioned in previous posts? (Revving at WOT for 20 mins at the end of the day - really!!)

[zenoahphobic]

Seeing we have time to wait (OP findings due next April) I hope I am not criticised for dragging out the thread.

I did say that emission figures must have been fudged; as fuel that is meant for combustion is going elsewhere. For running purposes it is being contained albeit within the oil. It is disappointing that frequent oil changes seems to be the solution. Not very environmentally friendly as more dirty oil needs to be disposed of eventually polluting the planet more. And I am being deliberately sarcastic in saying that what would the OB manufacturers care, so long as it doesn't leave the engine while it is operating!

Of course this fuel in the oil was once mist and should have been recycled before it mixed with the oil - just as it is done with automobiles crankcase ventilation (not) systems.

No one has highlighted that this process (issue) is a result of the fuel mist condensing on the cylinder walls and therefore would have been unable to be collected by conventional means (sucking up the vapour and sending it back to the inlet).

This highlights a blurring of opinion of what is happening. Optimal or whatever engine operating temperature is a bit of a furphy. The only thing that needs operating temperature is the combustion mixture! Everything else, everything else can remain cold. This includes the engine oil! As you raise temperatures you also create greater molecular activity. These can be seen as increased friction wear, greater chemical reactions such as in corrosion, and increased oil breakdown; to name a few.

So if one was to improve on these poorly designed engines one could start by looking at where higher than ambient temperatures are actually required, and address it from there.