B&S sudden white smoke on startup

[SC Maintenance]

I have a 140CC B&S engine - no choke type - on a toro push mower. Its season 10 - maybe 30-40 hours a year? Run only E0, change the plug, oil and air filter every spring and vacuum the filter out a couple times a season. I have never had any issues. Until yesterday.

Yesterday I give it a pull. It was a kind of limp wristed pull, which is usually plenty - nothing. Gave it 5 or 6 real pulls and it finally sputters, blows a huge cloud of white smoke, for about 10 seconds, clears up, starts running properly. Not good - white smoke is oil correct? Anyway its running fine so I mow the lawn. Didn't lack power. Didn't use anymore fuel than usual best I can tell.

Today I pulled the plug - didn't look burnt but the bottom was covered with some oil. Replaced the plug, vacuumed out the air filter. Its not overfull of oil - just at the full mark on the stick or maybe a touch over.

The intake where the crankcase hose enters had a little oil film but not dripping. I checked the crancase breather tube - it looks open from the top. Getting the other end off would be a bit of a chore - I would need to take the carb off to get my hand in there. I can't see the crankcase end plugging could it?

Anyway fired it up again cold. Another puff of white smoke, much smaller but for sure there - this time only a second or two, then cleared up and ran fine.

So thoughts? Did it suddenly start weeping oil? Why all of the sudden and only on startup.

 

[Soft Cars]

Have you tipped the mower on its side recently?

 

[PontiacHO]

With my sorry little mower: if the air filter gets dirty it pulls more oil past the rings. Owned another mower that the float was heavy and allowed raw fuel to drain into the cylinder washing down the rings causing hard starting and a puff when started.

 

[football]

1) A bad needle and seat can dump a ton of fuel into the engine. The oil level will be high.

2) synthetic oil with lots of hours can smoke. Change the oil and try SAE30 conventional.

3) drain the oil. Refill with SAE30 oil. Fill the oil to the halfway point on the dipstick. Keep it there at the halfway point.

4) monitor the oil level. If it goes up from halfway point on the dipstick, then your engine is dumping fuel into the oil. Replace the carburetor or the needle and seat .

That should fix your issue (small engine mechanic years ago)

(A small puff of smoke on startup is pretty normal)

 

[jhellwig]

The way the “evap” system works on these is there is a tube at the top of the filler neck in the gas tank that dumps gas right onto the air filter If you over fill it. Probably washed the oil down on it and it made its way into the intake.

 

[hemitom]

white smoke is usually not oil , sure it wasn't light blue did it smell like oil burning ?
These engine's are finicky about air ! change the filter and plug and report back.

 

[Oliveoil2]

Sounds like oil over-fill to me.

 

[wag123]

I have a 140CC B&S engine - no choke type - on a toro push mower. Its season 10 - maybe 30-40 hours a year? Run only E0, change the plug, oil and air filter every spring and vacuum the filter out a couple times a season. I have never had any issues. Until yesterday.

Yesterday I give it a pull. It was a kind of limp wristed pull, which is usually plenty - nothing. Gave it 5 or 6 real pulls and it finally sputters, blows a huge cloud of white smoke, for about 10 seconds, clears up, starts running properly. Not good - white smoke is oil correct? Anyway its running fine so I mow the lawn. Didn't lack power. Didn't use anymore fuel than usual best I can tell.

Today I pulled the plug - didn't look burnt but the bottom was covered with some oil. Replaced the plug, vacuumed out the air filter. Its not overfull of oil - just at the full mark on the stick or maybe a touch over.

The intake where the crankcase hose enters had a little oil film but not dripping. I checked the crancase breather tube - it looks open from the top. Getting the other end off would be a bit of a chore - I would need to take the carb off to get my hand in there. I can't see the crankcase end plugging could it?

Anyway fired it up again cold. Another puff of white smoke, much smaller but for sure there - this time only a second or two, then cleared up and ran fine.

So thoughts? Did it suddenly start weeping oil? Why all of the sudden and only on startup.

After 10 years of use it's getting old. This is perfectly normal for an aluminum bore B&S engine. It can run another 10 years or longer like this if you keep an eye on the oil level.

 

[SHOZ]

My old John Deere F510 will do that once or twice a year. Smoke for a good 5 minutes when it does it. Other than that it does not use oil. I just figured it was making a sacrifice to the gods.

 

[SC Maintenance]

Thanks everyone!

Have you tipped the mower on its side recently?

No

1) A bad needle and seat can dump a ton of fuel into the engine. The oil level will be high.

2) synthetic oil with lots of hours can smoke. Change the oil and try SAE30 conventional.

3) drain the oil. Refill with SAE30 oil. Fill the oil to the halfway point on the dipstick. Keep it there at the halfway point.

4) monitor the oil level. If it goes up from halfway point on the dipstick, then your engine is dumping fuel into the oil. Replace the carburetor or the needle and seat .

It is SAE30 and its pretty new, but it does seem a little higher than I thought and it does smell a little gassy. So I will change it and keep it a little lower as well. Unfortunately the only way to drain I can find is to dip it and drain out the dipstick - so I will need to let it sit a couple days after.

I also thought about a sticking needle - but its white smoke? Either way, where is a good place to buy a carb? I would rather get a new one and I can clean my old one at my leisure. Are the chines ones on Amazon worth bothering with, or where else can I buy one?

Also the manual lists two carb options- date code before and after 18070100. I assume that is 2018 or????

These engine's are finicky about air ! change the filter and plug and report back.

Just changed the plug today. I have a new air filter here as well so on it goes.

Thanks for the advice. I will report back in a couple days after I have all this done.

 

[JamesBond]

My mower smokes on start up and shut down when the air filter is clogged up.

 

[SC Maintenance]

Thanks again all for your help.

Last night I dumped the oil - via the dipstick tube only way I know how. I changed the air filter even though the old one looked pretty good, and the plug has about 10 minutes on it. I metered slowly in some oil and let it sit overnight. It was just at the bottom hole in the dipstick. Figure I would fire it up to burn off anything that got in it on its side for the real test again tomorrow.

Fired it up - a very tiny puff of black / blue smoke - I would say normal for a carburetor startup but I honestly never paid much attention before - definitely not the same color and much, much smaller. No white smoke at all. So I am pretty convinced the last couple times was oil not gas.

Will try again tomorrow. I will also make sure I don't fill it above 3/4 on gas per the comment above about the "evap" overflow. I wonder if I filled my crankcase with gas previously.

Will do so again tomorrow and see how it goes. I may not really know until I run it for a full mowing and let it sit.

 

[tnt_motorsports]

Thanks again all for your help.

Last night I dumped the oil - via the dipstick tube only way I know how. I changed the air filter even though the old one looked pretty good, and the plug has about 10 minutes on it. I metered slowly in some oil and let it sit overnight. It was just at the bottom hole in the dipstick. Figure I would fire it up to burn off anything that got in it on its side for the real test again tomorrow.

Fired it up - a very tiny puff of black / blue smoke - I would say normal for a carburetor startup but I honestly never paid much attention before - definitely not the same color and much, much smaller. No white smoke at all. So I am pretty convinced the last couple times was oil not gas.

Will try again tomorrow. I will also make sure I don't fill it above 3/4 on gas per the comment above about the "evap" overflow. I wonder if I filled my crankcase with gas previously.

Will do so again tomorrow and see how it goes. I may not really know until I run it for a full mowing and let it sit.

FWIW you might want to add a little more oil if it’s right at the add line before a full cut. Mower’s are splash lubed so I prefer not to run it on low.

Just my $0.02

 

[SC Maintenance]

FWIW you might want to add a little more oil if it’s right at the add line before a full cut. Mower’s are splash lubed so I prefer not to run it on low.

Just my $0.02

Yes, I measured it out carefully and it took 14 oz to get to that bottom hole. I think spec is 16 oz?

I added one more ounce - see where I end up in the morning. I assume unlike cars you check this when cold? After its run its all up the stick and there is no realistic way to measure anything.

 

[Ride_Red]

Yes, I measured it out carefully and it took 14 oz to get to that bottom hole. I think spec is 16 oz?

I added one more ounce - see where I end up in the morning. I assume unlike cars you check this when cold? After its run its all up the stick and there is no realistic way to measure anything.

Hot or cold doesn't really matter much on a lawnmower. Pull the dipstick and wipe it off. Then insert to get a reading on the oil level.
If checking after mowing, I usually let it sit for a few minutes for the oil to settle before checking the oil level.

 

[tnt_motorsports]

Yes, I measured it out carefully and it took 14 oz to get to that bottom hole. I think spec is 16 oz?

I added one more ounce - see where I end up in the morning. I assume unlike cars you check this when cold? After its run its all up the stick and there is no realistic way to measure anything.

As a habit I always check oil cold, regardless if it's OPE or a vehicle.

Just my $0.02

 

[SHOZ]

Started my JD Kawi today and no smoke. Almost 10 hrs on it. Oil runs hot at 250F or so at the end.

 

[football]

Hot or cold doesn't really matter much on a lawnmower. Pull the dipstick and wipe it off. Then insert to get a reading on the oil level.
If checking after mowing, I usually let it sit for a few minutes for the oil to settle before checking the oil level.

My mowers always show about 1/4 higher with hot oil than checking cold before running the engine.

I think checking cold gives a more accurate reading. I always check my oil so I have a habit of keeping it in the middle of the dipstick.

 

[SC Maintenance]

Round 3. I added 1 more ounce of oil. Then I learned that one side of the dipstick reads different than the other side. So one side is now at half, and the other side is just filling the bottom hole. From being not straight at the bottom - I don't know? Which one or is either accurate - sounds not like an exact science anymore.

Wheeled it out, gave it one real pull and it fired right up - not one puff of smoke - of any color.

?

I guess I need to mow some grass and see what happens next.

 

[Trav]

Try a splash of Berrymans Chemtool in every tank, you will never have carb issues guaranteed.