Anyone know small engines? Weird gas leak.

[Jacobson]

Honda GCV160 5.5
Attached to a log splitter.

Engine sputtered to a stop, and I noticed gas leaking from the air filter!
Air filter was soaked. There was even gas pooled in that cavity!

I took off the air filter housing to take a closer took.

I checked the gas line, and it did not appear to be dripping anywhere.

I noticed the gas was coming from that wet black gasket on the left.

I also noticed wetness under that muffler grille area.
Black water (or gas) was coming off that.

It was tricky to line up the 3 gaskets with the long bolts. But, I re-installed everything, tightened it all up, and the leak seems to be gone, and the engine runs again.

I know the carb was rebuilt recently. Could the air filter housing bolts that keep the filter/carb/intake all held together have been loose? Would this cause the gas to backflow into the air filter?

 

[gotmud13613]

Your float was sticking, after you removed it, it re-seated itself.

 

[Wakefield]

Float may have gasoline inside of it.

 

[Buster21]

I agree with the stuck float theory. I had a snow blower that was leaking gas just like that. The fuel had varnished the bowl and the float would stick to the bottom of the bowl and would not return up to push the needle into the seat. I cleaned it all out with carburetor cleaner put it back together and worked fine. You might also have a worn out needle and seat and it just won't seal anymore.

 

[Jacobson]

What is the float? Can someone school me?

 

[Sheriff Roscoe]

The float is inside the carburetor bowl and is used to control the level of gasoline within the bowl. There is a float needle attached to the float. As the float falls, the connected needle falls with it and opens to allow more gas in the bowl. As the float rises, the connected needle rises with it into a "tube" and reduces the flow of gas into the bowl. When the bowl is full, the needle should fully seat into the tube thereby shutting off the flow of fuel into the bowl.

Your float could have a hole in it thereby filling with gas and no longer floating. The float needle could have debris on it not allowing it to fully seat and therefore no shutoff the gas flow. Or the float need could be worn such that gas is leaking around it not shutting off the gas flow. Lastly, the needle is attached to the float my a small piece of metal called the tang. This tang can be bent (very slightly!) to "adjust" when the needle seats in relation to the float level.

 

[Sheriff Roscoe]

BTW, do a Youtube search for "carburetor float needle adjustment". This should greatly help understand what I tried to explain above.

 

[theoldwizard1]

Your float could have a hole in it thereby filling with gas and no longer floating.

The float is a "balloon" made out of thin brass. The float looks like a very small donut and is hinged on one side. If there is a leak in the "donut", the float sinks and will not shut off the flow of gas even when the bowl is full. a pin hole in a float is not common, but it does happen.

Adjusting the "tang" is almost NEVER required. (I have rebuilt dozen of small engine carbs over 30+ years. Never had to do it.)

 

[PBCampbell]

It's possible the actual float has gone south, more likely it's the needle seat. Find the engine tag with model and serial number and work from there toward your carburetor make and series. Once you have that info you can get an overhaul kit and over the winter tear down, soak, and replace parts so that you'll be good to go for another few years.

 

[justme-]

Floats have been injection molded plastic for over a decade. Leaks are almost ancient history these days. Odds are float is fine and needle had some debris holding it open. Watch for this as that can cause the crankcase to fill with gas via the breather and dilute the oil which will result in an engine seizing.
Common occurrence.

 

[Chris Stapley]

Check the oil level as well before running it much if the crankcase is filled with fuel this will take the crank bearings out quickly, a very common small engine problem..

 

[Jacobson]

Yes, the oil smells of gasoline.
Unfortunately, I ran the engine for 10 mins after I put it back together.

I will change the oil today with 10w-30

Is that the drain plug on the bottom right base?

 

[Jacobson]

If the engine was ruined, where could I order a replacement GCV160 engine?

 

[bob15]

Yes, the oil smells of gasoline.
Unfortunately, I ran the engine for 10 mins after I put it back together.

I will change the oil today with 10w-30

Is that the drain plug on the bottom right base?

Yes, that is the drain. Not sure if your engine has a dipstick or not (don't work on Hondas), but it doesn't you are probably to fill the oil until it is level to the inside of the fill tube.

If only run for 10 minutes, the engine is probably fine.

Not sure on your engine spec, but most small engines prefer 5w-30. Do a search on the net for proper oil weight.

 

[Jacobson]

Thanks Bob.

The engine case is labelled 10w-30.

The fill cap has a dipstick.

 

[Jacobson]

I changed the oil. Engine seems to be running fine, and no gas smell when I checked the dipstick.

If the engine is running along fine,
does that mean the float is definitely not stuck anymore?

 

[joel63]

I changed the oil. Engine seems to be running fine, and no gas smell when I checked the dipstick.

If the engine is running along fine,
does that mean the float is definitely not stuck anymore?

Does your machine have a manual fuel shutoff?

 

[theoldwizard1]

I changed the oil. Engine seems to be running fine, and no gas smell when I checked the dipstick.

If the engine is running along fine,
does that mean the float is definitely not stuck anymore?

Probably

Does your machine have a manual fuel shutoff?

A good addition to any small engine.

 

[Dust Devil]

Usually when the float sticks you get gas out of the overflow tube.

 

[theoldwizard1]

Floats have been injection molded plastic for over a decade.

I must just work on old engines ! I had 2 carburetors apart this year, 1 Briggs & Stratton and 1 Tecumseh, and both were brass.


It is interesting that all "modern" (<20 years old) small, single cylinder engines use carburetors that are almost identical. The main jet is the bowl nut. Bowl uses a rubber gasket between it and the carburetor body. Donut shaped float.

I maintain the family fleet of outdoor equipment and actually stock bowl nut sealing washers, carburetor gaskets and intake manifold gaskets and rebuild kit (needle, seat, rubber bowl gasket). These are all cheap when you buy them on eBay.

 

[theoldwizard1]

Usually when the float sticks you get gas out of the overflow tube.

What overflow tube ? Not on these carbs.

 

[purplezr2]

I must just work on old engines ! I had 2 carburetors apart this year, 1 Briggs & Stratton and 1 Tecumseh, and both were brass.


It is interesting that all "modern" (<20 years old) small, single cylinder engines use carburetors that are almost identical. The main jet is the bowl nut. Bowl uses a rubber gasket between it and the carburetor body. Donut shaped float.

I maintain the family fleet of outdoor equipment and actually stock bowl nut sealing washers, carburetor gaskets and intake manifold gaskets and rebuild kit (needle, seat, rubber bowl gasket). These are all cheap when you buy them on eBay.

I have never seen anything BUT plastic floats...... But I'm young(30)

 

[Jacobson]

Does your machine have a manual fuel shutoff?

Yes, why?

 

[Advan]

I've seen both brass and plastic floats fill up and stop "floating". In my limited experience, it actually seems to be a more common problem than worn float needles and seats. I've kinda made a habit of turning the fuel off and running my carbs dry every time I'm done using power equipment (When possible). I've heard conflicting opinions on doing this, but it works well for me!

 

[joel63]

Yes, why?

Shutting it off when not in use prevents the possibility flooding in the event that the float system (needle and seat and float) malfunction.

Commonly used when the fuel tank feeds the carb by gravity.

 

[theoldwizard1]

I have never seen anything BUT plastic floats...... But I'm young(30)

some of my equipment is older than you. A LOT older than you !

 

[Ponchoguy]

I must just work on old engines ! I had 2 carburetors apart this year, 1 Briggs & Stratton and 1 Tecumseh, and both were brass.


It is interesting that all "modern" (<20 years old) small, single cylinder engines use carburetors that are almost identical. The main jet is the bowl nut. Bowl uses a rubber gasket between it and the carburetor body. Donut shaped float.

I maintain the family fleet of outdoor equipment and actually stock bowl nut sealing washers, carburetor gaskets and intake manifold gaskets and rebuild kit (needle, seat, rubber bowl gasket). These are all cheap when you buy them on eBay.

---I can tell you the brass ones are still out there and you can still purchase them. The "big 3" of the small engine aftermarket parts world (Stens, Oregon and Rotary) still sell the brass floats for many engines, including Tecumseh.

Many Briggs carbs now are plastic and there's no float. The diaphragm kit goes bad and for $2 for a kit, you can get these running great all day. I have "curbside shopped" several with bad fuel and these $2 kits get them running like new again .

 

[theoldwizard1]

Many Briggs carbs now are plastic and there's no float. The diaphragm kit goes bad and for $2 for a kit, you can get these running great all day.

Most 2 strokes have diaphragm carbs. The quick way to tell is they have 2 fuel line. A feed and and a return fuel line.

The biggest problem with small 2 stroke fuel system is vacuum leaks from old fuel. lines. Any 2 stroke that is older than 5 years old and won't start should get ALL new Tygon fuel lines. Quick and easy.

 

[PBCampbell]

Briggs likes Walbro carbs and they went to plastic floats over a decade ago I think. I can't recall ever seeing a Zama 4 stroke carb and Tecumseh always had their own carbs as far as I remember. My 91 Ford Ranger's fuel pump (sending unit) had a brass float as a replacement a few years ago and a Nikko(?) carb on a Vanguard(Daihatsu?) uses brass floats as well, so they're still out there.
I can't recall seeing a small engine carb with an "overflow"(return?) line. The only reason I suggest a rebuild is I've seen problems with the seats going bad and making it incapable for the needle to seat.

 

[Buster21]

I rebuilt my carb on my 20 year old snow blower several times: new needle, seat, float etc. I could never stop the gas from leaking, it had to be getting past the needle and seat somehow. I finally installed a shut off valve just past the tank and when I am done I just shut off the valve and let the engine run out of gas and stop on it's own. No more leaking gas. And by the way it has a brass float.

 

[Wakefield]

Tecumsehs had a very simple way to pop out the old seat with a special screwdriver,the special screwdriver was then used to push in the new seat and then the needle could also be replaced the screwdriver side even served as a guide to try to see if the float height was right

I think a shut off valve and a little screen filter are good to have in the fuel line
when the mower is transported in a bumpy riding pickup truck the shaking might cause the fuel to overfill the carburetor without a shutoff being closed

 

[theoldwizard1]

Tecumsehs had a very simple way to pop out the old seat with a special screwdriver,the special screwdriver was then used to push in the new seat and then the needle could also be replaced the screwdriver side even served as a guide to try to see if the float height was right

You can use a small, coarse thread, screw like a drywall screw, twisted into the seat and then pull it out.

Use the **** end of an appropriate sized drill bit to seat the new one.

 

[Jacobson]

I watched a few videos of how a carb works. How exactly does a stuck float cause gas to flood into the intake and the air filter (both directions) Does it typically get stuck closed (no fuel) or stuck open (bowl fills to capacity, then what?)

 

[Wakefield]

I watched a few videos of how a carb works. How exactly does a stuck float cause gas to flood into the intake and the air filter (both directions) Does it typically get stuck closed (no fuel) or stuck open (bowl fills to capacity, then what?)

goes down to bottom because too heavy to float or stuck because of sticky varnish to bottom of bowl
where the gas goes depends on whether the air pipe/air horn is horizontal or up/down (side draft,updraft or downdraft carburetors such as were on large old fashioned Briggs engines-trying to remember the 10 horsepower cast iron engine on an old Toro commercial walk-behind
if the engine happened to stop with the intake valve open fuel could very well seep in-also that valve is cracked open just a little bit during the compression stroke on some old Briggs engines when you wouldn't expect it to be open-was called "Easy Spin" I think.

 

[Wakefield]

When you leave a Tecumseh mower engine sitting a couple years with gas in it-can slowly evaporate from the carburetor,more probably goes in from the tank until most of the gas is gone and the carb begins to dry out-at that point all the gum is in the bottom of the bowl and the float sits in it on the bottom and becomes stuck-at least that is my theory-I like to close my fuel line shutoff valves and run out some of the fuel before I shut down the engine-but might not be good for it to keep it sputtering lean too long-maybe shut down as soon as it begins to sputter after closing the shutoff-also like to put Stabil or something similar in my gas can when I first buy gas
best to store them empty during the offseason although some claim better to fill them with ethanol-free gas with stabilizer before storage
better to avoid ethanol gas if possible but even ethanol free gas can go bad if stored too long

 

[Ponchoguy]

Most 2 strokes have diaphragm carbs. The quick way to tell is they have 2 fuel line. A feed and and a return fuel line.

The biggest problem with small 2 stroke fuel system is vacuum leaks from old fuel. lines. Any 2 stroke that is older than 5 years old and won't start should get ALL new Tygon fuel lines. Quick and easy.

The basic Briggs 4 cycles do too. The one I use at my grandparent's was a 2006 and was thrown out a year later. I picked it up, pumped out the bad gas, put in fresh, started right up. A half of year later, I TLC'd the whole thing and put in the $2 diaphragm, and it's been good ever since. I just change the oil regularly, change/clean the plug and air filter and it's happy mowing .

 

[steed andersen]

The bowl vent for this engine also uses the black gasket between the carburetor and engine. If someone had it off for work and it was installed upside down it will not vent
and allow the float to return to its closed position.

 

[justme-]

First - the easiest way to drain the oil from a regular walk behind mower is usually pull the dipstick and tip the whole thing over. You'll notice the dipstick is almost always on the opposite side the carb is - helps since that keeps the carb up and helps prevent flooding or oil entering the valves/carb/muffler while draining. Professionally we service hundreds of mowers every season and never pull a drain plug on a walk behind.

As to oil- F head/flat head engines (like Tecumseh and briggs) should use SAE30. 10w30 if that's all you have will do just fine. All overhead cam engines (most hondas, newer Briggs) should use 10w30 unless it's a snow blower or will be used in cold weather, which should then get 5w30.

There are many ways to cause a float/needle to stick - evaporating fuel leaving deposits sticking the float down is one - not always the float stuck to the bowl, but the residue on the pivot will cause it, as will the residue on the needle and seat keeping them from sealing. Same for drying out of the needle or seat from fuel or age. When the needle doesn't stop the flow of gas the gas flows into the intake and starts filling what it can which is almost always the breather (rubber connector to a metal tube on some older engines, just a bent rubber hose on newer that goes to a breather "box" on the block) which is for crank case ventilation and gas combustion - think PCV for a car. Fuel entering here generally goes right into the crankcase diluting the oil and can actually fill the entire crankcase effectively hydrolocking the engine.

If the gasket between the carb/manifold is blocking the bowl vent you'll also get hard starting and poor running because the gas can't get into and out of the carb correctly. Those symptoms should manifest far before causing a sticking float or flooding.

Yes you could order a replacement engine should this one die, but cost wise you''d be better off either having this one rebuilt (depending on the damage if/when it happened) or buying a new mower. Often an engine is 90% the cost of the mower.