Engine smokes

[bertsmobile1]

Your engine has a blown head gasket.
Nothing to do with having had an oil change .. it's a single cylinder overhead valve B&S engine, so it was ALWAYS gonna get a blown head gasket.
They ALL do.
Your local B&S dealer's Service Manager will know exactly how much it will cost to fix coz it's such a common problem.

That is a rather bold statement , particularly as Zippy specified it was pumping out BLACK smoke which is usually considered to be the sign of flooding

 

[slomo]

Your engine has a blown head gasket.
Nothing to do with having had an oil change .. it's a single cylinder overhead valve B&S engine, so it was ALWAYS gonna get a blown head gasket.
They ALL do.
Your local B&S dealer's Service Manager will know exactly how much it will cost to fix coz it's such a common problem.

LOL

 

[OzPete]

That is a rather bold statement , particularly as Zippy specified it was pumping out BLACK smoke which is usually considered to be the sign of flooding

I can't argue .. yes a bold statement, but I think that we can all agree that a blown head gasket is highly likely to be the case.
And the black smoke ? .. if it was flooding enough for black smoke it wouldn't run well enough to mow.
It's more likely to be the choke is sticking, and staying stuck shut after starting.
Also extremely common coz the plastic choke shafts swell, and the little return spring isn't strong enough to open the choke butterfly.
Sometimes the engine's vibration will jog the choke open, but not always.
And if the choke's return spring is broken (or dislodged) then the choke can vibrate itself between open & shut, thus varying the symptom.

 

[Scrubcadet10]

Your engine has a blown head gasket.
Nothing to do with having had an oil change .. it's a single cylinder overhead valve B&S engine, so it was ALWAYS gonna get a blown head gasket.
They ALL do.
Your local B&S dealer's Service Manager will know exactly how much it will cost to fix coz it's such a common problem.

blown head gasket won't allow fuel into the crankcase.

 

[bertsmobile1]

I can't argue .. yes a bold statement, but I think that we can all agree that a blown head gasket is highly likely to be the case.
And the black smoke ? .. if it was flooding enough for black smoke it wouldn't run well enough to mow.
It's more likely to be the choke is sticking, and staying stuck shut after starting.
Also extremely common coz the plastic choke shafts swell, and the little return spring isn't strong enough to open the choke butterfly.
Sometimes the engine's vibration will jog the choke open, but not always.
And if the choke's return spring is broken (or dislodged) then the choke can vibrate itself between open & shut, thus varying the symptom.

Inteks do eat head gaskets but the ratio of failed float vales to blown head gaskets would be around 20 :1 in my workshop.
Now I only do around 300 tickets a year and that covers everything from sharpening the blades on hand mowers to rebuilding 72" commercial ZTR's.
Intek head gasket replacements have been getting fewer over the years since B & S left the mating surfaces rough cut .

 

[OzPete]

blown head gasket won't allow fuel into the crankcase.

Original Poster mentioned that he had BLUE smoke emitted, and some loss of power in-the-cut.
But he didn't actually SAY that there was fuel into the crankcase - he just confirmed that he could smell gasoline on the dipstick.
Which, unless he has no sense of smell, he SHOULD be able to .. Because if the engine does, (as I suggested), indeed have a blown head
gasket, then in that case it's normal that after each intake stroke, when the piston starts it's upward compression stroke, for some of that
newly introduced fresh fuel/air mix to be forced past the leaking head gasket and out into the pushrod gallery, and thus into the crankcase
where the fuel will be smelt.

 

[Scrubcadet10]

Original Poster mentioned that he had BLUE smoke emitted, and some loss of power in-the-cut.
But he didn't actually SAY that there was fuel into the crankcase - he just confirmed that he could smell gasoline on the dipstick.
Which, unless he has no sense of smell, he SHOULD be able to .. Because if the engine does, (as I suggested), indeed have a blown head
gasket, then in that case it's normal that after each intake stroke, when the piston starts it's upward compression stroke, for some of that
newly introduced fresh fuel/air mix to be forced past the leaking head gasket and out into the pushrod gallery, and thus into the crankcase
where the fuel will be smelt.

and when cranking it blows it black smoke.....
While sitting the fuel seeps past the float needle, fills up the bowl and flows into the combustion chamber (and flowing past the rings and contaminating the oil and raising the oil level ) causing a very very rich starting condition.
I'm just going based off of every blown head gasket i've replaced on a small engine, i've never smelled or found oil in the crankcase... now it could also depend on where the gasket blows at as well.

@zippy2 Is the oil above the FULL mark on the dipstick?

 

[zippy2]

and when cranking it blows it black smoke.....
While sitting the fuel seeps past the float needle, fills up the bowl and flows into the combustion chamber (and flowing past the rings and contaminating the oil and raising the oil level ) causing a very very rich starting condition.
I'm just going based off of every blown head gasket i've replaced on a small engine, i've never smelled or found oil in the crankcase... now it could also depend on where the gasket blows at as well.

@zippy2 Is the oil above the FULL mark on the dipstick?

No. I always have to add oil after mowing. The oil smells like gas and is very thin. The last time I had a blown head gasket, the mower would not crank at all.

 

[sgkent]

it sounds like the gasoline drips into the oil, making it look overfull, then you run it and the gasoline boils off at the same time the thin oil washes past the rings. It will belch black smoke when it first starts running and grey smoke when running. When you are done the oil is low. If this is the situation, each time you run it you have metal on metal wear because the oil is not protecting, If this is the situation the engine will fail catastrophically soon. One fix is to install a shut off in the fuel line and use it when the mower is turned off. The oil should not feel thin or smell like gasoline.

 

[zippy2]

it sounds like the gasoline drips into the oil, making it look overfull, then you run it and the gasoline boils off at the same time the thin oil washes past the rings. It will belch black smoke when it first starts running and grey smoke when running. When you are done the oil is low. If this is the situation, each time you run it you have metal on metal wear because the oil is not protecting, If this is the situation the engine will fail catastrophically soon. One fix is to install a shut off in the fuel line and use it when the mower is turned off. The oil should not feel thin or smell like gasoline.

This makes sense!