Gas in oil

[wewsnu]

Hello all,

I purchased a 42" MTD generic (Lawn Machine or something) mower with a 16.5hp B&S motor for $150. It cranked hard but started when I looked at it. I got it home and put a new plug and fuel filter in it, along with performing an oil change (Valvoline ML 10W-30, sale + thickness = purchased). AFTER I got my new oil in it and the maintenance completed, I tried to start it, no luck.. It must have stopped part way through a "cycle" and there had to be a lot of vacuum in the head because gas began to pool in the carb, spilling everywhere, coming out of where the air cleaner should have been. I clamped the fuel feed hose, pulled the plug, and cranked the motor a few times expelling gas from the cylinder. I then went and purchased a new battery, and mowed my lawn. Approx 2 acres. I know I need to adjust the valves as it still cranks a little slow in one spot. I'm not sure there's anything anyone can tell me to re-assure me to the point of believing the oil hasn't been contaminated by gas, but please try. Please try! I mean, heating the oil from mowing for 2 hours could possibly have "boiled" off some of the fuel in the gas right? And I mean, I don't know anything about what oiling goes on inside mower engines, maybe gas wouldn't have got into the oil? Can anyone tell me something reassuring, or should I just buy another quart of oil? It was an atrocious process to change the oil, rather than neatly pouring out of a hole under the drain plug as I assumed it would have, it spilled onto the entire base of the mower, the deck, basically just poured out everywhere but the hole I had the pan under.

Thanks & have a good weekend

 

[Quest]

Plse by first getting us the engine serial number.

Guessing it's a carb issue at this moment, but won't hazard an educated guess until we get the serial number info from you.

Q.

http://www.briggsandstratton.com/us/en/support/faqs/engine-codes-model-numbers

 

[old1]

You probably got a little gas in the oil, but it probably boiled off in 2 hours of mowing Is it an OHV or flathead engine? Personally I don't believe in using multigrade oil in ope, unless it is full synthetic, as Briggs recommends. Next time you take the oil drain plug out, can you put in a pipe to extend the drain out to the side farther? And of course just leave it there for next time.

 

[old1]

As the carb running over, if it doesn't do it again after mowing, it was probably just a temporally stuck float. Happens sometimes with gravity feed carbs. An in line shut off is not a bad idea.

 

[wewsnu]

The mower says B&S 5bsx.5012 "family" on a plate attached to it, only numbers I could find when looking for plug info. I wasn't really looking to resolve any "issue" just seeking reassurance I didn't kill the fresh oil I put in it. But hey, any help is appreciated..

EDIT: Interesting.. so there's an issue with the float? And it didn't just flood because it was under some sort of vacuum? Great, the things I have to look forward to. It's OHV. Now I'm worried not just about the contaminated oil but that I parked it in my garage and it could suddenly flood with gasoline at any given moment!

Thank you!

 

[mlatour]

Did you tilt the mower on it's side to drain the oil?

If so the float could of stuck open once level and overflowed into the intake/open valve/cylinder etc.

My mower starts up a bit rich after an oil change as I drain it thru the fill tube / laying on it's side.

 

[bubbatime]

Originally Posted By: wewsnu
It must have stopped part way through a "cycle" and there had to be a lot of vacuum in the head because gas began to pool in the carb, spilling everywhere, coming out of where the air cleaner should have been.


Vacumm in the head? Not sure about your reasoning, but the real reason is that the needle and sit in the carb are no longer working for one reason or another which is causing gas to continue to flow through the carb. The $5 jerry rig fix is to put a fuel shutoff on fuel line. Or you need to get the carb rebuilt. Engine vauum and part way through a cycle has nothing to do with it. You need a new needle and seat, possibly a float. Or just throw a $5 fuel shutoff on the fuel line. It should have one of those anyways but MTD would rather save 49 cents per unit.

 

[bubbatime]

Originally Posted By: mlatour
Did you tilt the mower on it's side to drain the oil?

If so the float could of stuck open once level and overflowed into the intake/open valve/cylinder etc.

My mower starts up a bit rich after an oil change as I drain it thru the fill tube / laying on it's side.


Nobody tilts a 42" riding lawn mower on it's side for an oil change. If they do, they are doing it wrong.

 

[wewsnu]

Originally Posted By: bubbatime


Vacumm in the head? Not sure about your reasoning, but the real reason is that the needle and sit in the carb are no longer working for one reason or another which is causing gas to continue to flow through the carb. The $5 jerry rig fix is to put a fuel shutoff on fuel line. Or you need to get the carb rebuilt. Engine vauum and part way through a cycle has nothing to do with it. You need a new needle and seat, possibly a float. Or just throw a $5 fuel shutoff on the fuel line. It should have one of those anyways but MTD would rather save 49 cents per unit.


Thanks, I had no idea there was an issue with the carb. I figured it was because there was suction or pressure somewhere, on whatever is on the end of this black hose that goes from the carb to up under the engine cover. I'll see if I can't find a shut off valve at the parts store next time I'm there, probably buying oil for the mower! If I can find more numbers off the motor I'll buy a rebuild kit for it.

 

[DSparks]

If it has one of those plastic external pulse type fuel pumps they go bad and fill the engine up with fuel also.....

 

[wewsnu]

Thanks for your reply. I know nothing about mower engines. I didn't see anything between the lines between the tank and the carburetor going to any pump but I suppose that black hose that I can't trace could be going to a pump.

 

[old1]

I think the black hose you are referring to is the crankcase breather hose. Also, as I said before if it has not continued to leak gas, it was probably just one of those fluke things that held the float needle open temporally. A hair or grain of dirt so small you need a magnifying glass to see can do it, and then wash itself out. But a shut off to turn the gas off when not using it is a good safety device. Of course if all is right they SHOULDN'T be needed. But then you could say dual brake cylinders or even seat belts in a car SHOULDN'T be needed either.

 

[wewsnu]

Originally Posted By: old1
I think the black hose you are referring to is the crankcase breather hose. Also, as I said before if it has not continued to leak gas, it was probably just one of those fluke things that held the float needle open temporally. A hair or grain of dirt so small you need a magnifying glass to see can do it, and then wash itself out. But a shut off to turn the gas off when not using it is a good safety device. Of course if all is right they SHOULDN'T be needed. But then you could say dual brake cylinders or even seat belts in a car SHOULDN'T be needed either.


Thank you, I have half a can of seafoam sitting around, I could dump some through I suppose, before the oil change. The last thing I want is a gas puddle in my garage, so a shut off valve is on my shopping list. I know there's dirt in the tank, I can see it, very macroscopic. I'm hoping something small like you said got through when I changed the fuel filter. So far no leaks. If anyone knows the proper oil capacity I'd appreciate it. A quart seemed to bring it into the "safe" range..

Thanks for your help.

 

[Rand]

extremely common on those, just go get a 4$ fuel shutoff valve and 2 hose clamps.. and mow with it for another 10 years.

I'd change the oil after you install the fuel shutoff.

When you check the oil be extremely careful to note the highest "wet point"

you can have gasoline in the oil that will separate out and be on top of the oil.. then you don't notice its extremely overfull because its transparent on the dipstick. It then gets blown into the exhaust making MASSIVE mess.

I've worked on 3-4 of these and they all had a leaky carb draining fuel into the oil.

 

[bubbatime]

If you can see dirt in your tank you need to unbolt the tank (two bolts) and flush it out. While its off, put a new fuel line on it with a Briggs fuel shut off and a Briggs red fuel filter. Shut off valve is about $5 and fuel filter about $4.

 

[Dallas69]

Oil changes don't have to be messy.
Get a piece of cardboard and make a funnel type piece for the oil to drain out on.
Alot of gas in the oil will just clean up the inside real good.Does it have a filter?
I would change the oil anyway.