# Honda Four stroke making oil.What making oil?



## matthewmagness (Oct 6, 2012)

Well my trip to the lake is called off.I pull the dipstick on my engine and oil comes out.What the crap..I changed it at the first of the summer and checked it a few times and looked good.So I drain it to find thinned oil by gas.Not good....Been looking around and found that this can be a problem with four strokes at low rpm (trolling or at idle.)So has anyone else gone through this?Hope I don't have major engine problems.


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## bassboy1 (Oct 7, 2012)

matthewmagness said:


> Well my trip to the lake is called off.I pull the dipstick on my engine and oil comes out.What the crap..I changed it at the first of the summer and checked it a few times and looked good.So I drain it to find thinned oil by gas.Not good....Been looking around and found that this can be a problem with four strokes at low rpm (trolling or at idle.)So has anyone else gone through this?Hope I don't have major engine problems.



The oil is definitely diluted by gas, and not water?

My experience suggests that 4 strokes making oil is more likely caused by water than by fuel, but not to rule out fuel.

Could be a matter of how you operate the engine (long idling, trolling, too much prop pitch), or could be an engine issue such as a fuel system leak, or it could be engine wear causing too much blow-by.

Best recommendation would be to run the engine at WOT on a more regular basis (assuming it gets lots of low RPM time), to see if the problem persists, and get a prop that allows the full throttle revs to stay right in the recommended zone.  This will at least determine if the problem is due more to outside factors, or if there is an internal engine issue.  

Also, more frequent oil/filter changes are probably a good idea if you continue to 'make oil.'


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## Alan in GA (Oct 7, 2012)

*Wot.....*

of course your motor MUST be checked out for gasket leaks, cracks in head/block.

About the WOT with 4 strokes. My little 40 hsp Mercury EFI is a 4 stroke. Talking to a Mercury mechanic about how to run it, he also said it  was designed to run full throttle much of the time. 40 years ago and running 2 stroke outboards, my dad trained me to run up to WOT, and then pull back to about 3/4 to 4/5ths throttle which he called 'cruising speed'. He believed it to be easier on fuel use and let the motor run easier.
My Merc mechanic disagrees and said WOT.
Hmmm.....might be another topic to post about.
Hope you get your motor figured out as to what's wrong. Gas or water in the oil is not good!


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## cetaws6 (Oct 7, 2012)

if its gas it could be an injector stuck? just throwing that out there


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## Luckybuck (Oct 7, 2012)

More chances it being gas in oil, is viscosity of oil very thin, can you smell dip stick for gas evidence.  Can you shut fuel off engine when finished running, this will eliminate most gas passing to sump.


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## Bugpac (Oct 7, 2012)

If its water it will look like chocolate milk, if its thin and still black fuel.


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## matthewmagness (Oct 7, 2012)

Almost positive it is gas.I have a pint in a glass jar if it is water it will start to separate.Water should start to settle down.I drained out the oil from the motor and put the plug back in going to check in a day or two to see if more gas has seeped back in.I have read that the pressure from heat in the gas tank can force fuel in.May be a stuck or broke ring.Although it is not burning oil or smoking.I let it idle most of the time when I fish because it is so quite and have done a lot of trolling with it.


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## bassboy1 (Oct 8, 2012)

Here is a good article on the subject.

HERE.

I'd definitely quit on the idling while fishing, for starters.  Certainly not helping anything.


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## matthewmagness (Oct 8, 2012)

Thanks I found that thread yesterday as well, lots of good info.I'm changing oil next week and going to stop extra idling try some small things first.I just have replaced my fuel pump as well that may have leaked a small amount prier to replacement.Need to check prop size as well the guy I got it from put a new SS prop on it.I don't want to miss out on fall fishing if I can get by till winter to deal with more major issues it would be great.


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## striper sniper (Oct 8, 2012)

That is ridicolous that is caused from ideling. I have ran my merc 4 stroke on idle half the summer pulling leadcore and dont have that issue. I work on small engines and know boat motors arent the same but we see this problem alot. Usually the needle gets stuck in the carb and fuel goes through it while its sitting causing that issue. One other possibility is tank not venting and pressure builds up pushing fuel through the system. Hopefully you can get it resolved, can definately blow it up if you run it that way long. Good Luck


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## matthewmagness (Oct 9, 2012)

The gas tank is not vented at all I noticed that it was swelled up.So that might be the cause I could only hope...So the gas can pass by the rings when the engine is cold right?


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## bassboy1 (Oct 9, 2012)

striper sniper said:


> That is ridicolous that is caused from ideling.



If it is fuel diluting the oil, perhaps, but if it's water (and it hasn't been posted for sure one way or the other - oil can retain some water before turning milky), the low temperatures involved in idling an outboard definitely make it much more prone than any other engine.

The moisture enters the oil of ALL engines, the difference is that most engines run warm enough to evaporate it off.  The thermostat in a small outboard is generally set in the realm of 135 degrees, whereas it would be around 200 in a car.  Furthermore, in a long idling scenario, the motor may not reach operating temperature, or even if the _motor_ does, the _oil_ may not, and thereby, the moisture accumulates.  

The moisture problem is generally unique to outboards - operating conditions of other types of engines tend to eliminate that problem.  

I'm not saying there isn't a fuel system issue, or if the motor was broken in poorly, and has excessive blow-by.  I'd just be hesitant to rule out water, as in my experience, it is more prevalent than a fuel issue (and I don't wrench on outboards daily, so I am dealing with a smaller sample size than a mechanic).


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## bassboy1 (Oct 9, 2012)

matthewmagness said:


> The gas tank is not vented at all I noticed that it was swelled up.So that might be the cause I could only hope...So the gas can pass by the rings when the engine is cold right?



Simple fix for that would be to unhook the fuel line during storage.  If you have a portable fuel tank (either no vent, or closeable vent), this is good practice for a multitude of reasons.  But to answer your question, it can.


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## Bugpac (Oct 9, 2012)

Gas will go by the rings, yes. And if its that full and it is water it would be milky, oil might take a few ounces of water per quart, sounds like you have a large amount of some substance in there. Is it getting fuel in the oil when its running, or just after it sits? Unhook the fuel line when sitting for sure. If the fuel pump runs on vacume, it likely could be entering through the fuel pump. If its injected the pressure should not be bypassing the injectors when sitting.


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## Alan in GA (Oct 9, 2012)

*not vented???*



matthewmagness said:


> The gas tank is not vented at all I noticed that it was swelled up.So that might be the cause I could only hope...So the gas can pass by the rings when the engine is cold right?



I don't think I've ever had a fuel tank that did not have a vent or vent screw. Is this tank 'made for' the motor or are you using something else for a fuel tank??
Definately could be the cause! [IMO].


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## Wild Turkey (Oct 9, 2012)

Making oil is typically a result of rings that havent seated yet. Yamaha 115-150 4 strokes are notorious for this.
Gotta break it in correctly then run it hard and hot enough to seat the rings. A lot of times this corrects itself over time.
How old is your motor?


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## HMwolfpup (Oct 9, 2012)

I had it happen to me and it was a mapping sensor that had gone bad. Replaced the sensor and haven't had that problem since.


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## btt202 (Oct 9, 2012)

I Got a BF25hp Honda 4 stroke Had the same problem ... Tank not vented in storage pressure builds up in the day time heat and jets not seat in carb . leaks into oil.


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## matthewmagness (Oct 9, 2012)

Alan in GA said:


> I don't think I've ever had a fuel tank that did not have a vent or vent screw. Is this tank 'made for' the motor or are you using something else for a fuel tank??
> Definately could be the cause! [IMO].


Yes it is a plastic 6 gal tank for outboards Blitz brand I think.No vent the and cap does not vent.


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## matthewmagness (Oct 9, 2012)

The engine is a Honda BF25A 25 hp tiller motor.Late 90's low hours on it. Carburetor not fuel inject.Engine is clean for the most part.Had the glass jar with some of the oil sitting since sat night no sign of water yet.


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## matthewmagness (Oct 9, 2012)

btt202 said:


> I Got a BF25hp Honda 4 stroke Had the same problem ... Tank not vented in storage pressure builds up in the day time heat and jets not seat in carb . leaks into oil.


So what did you do to your engine?


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## btt202 (Oct 9, 2012)

Changed oil !!!!! New gas tank thats has a screw vent on cap!!!!! and Carb. rebuild !!!!!!!  for new float jets


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## Alan in GA (Oct 29, 2012)

Makes me wonder if I should tighten the gasoline tank vent so much! Maybe just snug???


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## matthewmagness (Nov 20, 2012)

I changed the oil and added a shut off valve to the fuel line to close off fuel flow every time the engine is off.This should prevent any gas from being forced in the carbs due to expansion of the gas.I took the boat back out on the water this weekend for a fishing trip.Still getting gas in the oil after trolling for 3-4 hours at idle.From the time I changed the oil to the time I returned home there is no way expansion caused the fuel to enter the carbs because every time the engine was not running I closed the valve.I did however catch a nice fish! 

http://www.idofishing.com/forum/showflat.php/Number/415591/fpart/1/4-stroke-making-oil


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## angler557 (Nov 20, 2012)

Wild Turkey said:


> Making oil is typically a result of rings that havent seated yet. Yamaha 115-150 4 strokes are notorious for this.
> Gotta break it in correctly then run it hard and hot enough to seat the rings. A lot of times this corrects itself over time.
> How old is your motor?



This absolutely true. 

Years ago I bought a used Crestliner with a Yamaha F115 and it did the same thing. I spoke to the factory techs at a boat show and they said those four strokes need a hard break in so the rings will seat properly.

Other than the "making oil" problem, that was  a sweet little engine. Just bump the key and it would fire right up.

Brian


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