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Engine smokes
#1
Z
zippy2
Z
zippy2
I have a Craftsman YT3000 lawn tractor with a 21 hp B&S engine. Shortly after changing the oil in April, the engine starting smoking. I may have overfilled the crankcase. Now I have to add oil after every cut. When cranking, a huge amount of black smoke blows out the exhaust. During mowing a small amount of bluish smoke is emitted. No trouble starting or mowing, except that I notice a decrease in power when encountering higher grass/weeds. Is it the carburetor or rings on the piston? How much is this going to cost to have a professional repair it? TIA
#2
Scrubcadet10
Scrubcadet10
Pull the oil dipstick and smell of it.... does it smell like gasoline?
#5
sgkent
sgkent
that appears to be your problem. The carb float is stuck and allowing gasoline to overfill the oil. It is destroying the engine. You cannot run the engine until you fix the cause of the fuel in the oil and change the oil again. Just changing the oil will not solve the cause. And it would be too expensive to change the oil each time you go to use the engine. If you are lucky you caught it in time. But there is already damage done to the engine.
What is happening is that the carb float is not shutting off fuel so it drips into the engine. Then it runs down into the oil making you think you overfilled it. Then when it starts it runs rough with black smoke as all the excess fuel burns. Next the thin oil washes past the rings and burns, making the engine smoke. In addition the thin oil is causing bearing damage, damage to the rings and cylinder walls, and valve guide damage.
What is happening is that the carb float is not shutting off fuel so it drips into the engine. Then it runs down into the oil making you think you overfilled it. Then when it starts it runs rough with black smoke as all the excess fuel burns. Next the thin oil washes past the rings and burns, making the engine smoke. In addition the thin oil is causing bearing damage, damage to the rings and cylinder walls, and valve guide damage.
#6
Scrubcadet10
Scrubcadet10
^^^^^ what he said.that appears to be your problem. The carb float is stuck and allowing gasoline to overfill the oil. It is destroying the engine. You cannot run the engine until you fix the cause of the fuel in the oil and change the oil again. Just changing the oil will not solve the cause. And it would be too expensive to change the oil each time you go to use the engine. If you are lucky you caught it in time. But there is already damage done to the engine.
What is happening is that the carb float is not shutting off fuel so it drips into the engine. Then it runs down into the oil making you think you overfilled it. Then when it starts it runs rough with black smoke as all the excess fuel burns. Next the thin oil washes past the rings and burns, making the engine smoke. In addition the thin oil is causing bearing damage, damage to the rings and cylinder walls, and valve guide damage.
#7
Z
zippy2
Z
zippy2
Thanks for your reply. I have taken the carb off, but I can't get the screws off the bowl to inspect. Apparently a replacement carb is not available, only a tuneup kit. Advice?that appears to be your problem. The carb float is stuck and allowing gasoline to overfill the oil. It is destroying the engine. You cannot run the engine until you fix the cause of the fuel in the oil and change the oil again. Just changing the oil will not solve the cause. And it would be too expensive to change the oil each time you go to use the engine. If you are lucky you caught it in time. But there is already damage done to the engine.
What is happening is that the carb float is not shutting off fuel so it drips into the engine. Then it runs down into the oil making you think you overfilled it. Then when it starts it runs rough with black smoke as all the excess fuel burns. Next the thin oil washes past the rings and burns, making the engine smoke. In addition the thin oil is causing bearing damage, damage to the rings and cylinder walls, and valve guide damage.
#8
B
bertsmobile1
B
bertsmobile1
The 2 screw Nikki bowl screws strike again
Put the carb in a vice making sure you protect the flanges .
I use old inner tubes
Then with a power driver bit held by a 1/4" spannar push down hard on the end of the bit while turning the spanner
They are a PIA to remove
And they are a Posi-Drive head No 2 not a Phillips .
Put the carb in a vice making sure you protect the flanges .
I use old inner tubes
Then with a power driver bit held by a 1/4" spannar push down hard on the end of the bit while turning the spanner
They are a PIA to remove
And they are a Posi-Drive head No 2 not a Phillips .
#9
Z
zippy2
Z
zippy2
Thanks for advice! I fiddled around with the screws and got them off after trying to use a phillips head (oops!). Think I've found a total replacement on ebay. Will see.....The 2 screw Nikki bowl screws strike again
Put the carb in a vice making sure you protect the flanges .
I use old inner tubes
Then with a power driver bit held by a 1/4" spannar push down hard on the end of the bit while turning the spanner
They are a PIA to remove
And they are a Posi-Drive head No 2 not a Phillips .
#10
OzPete
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.
OzPete
Your engine has a blown head gasket.I have a Craftsman YT3000 lawn tractor with a 21 hp B&S engine. Shortly after changing the oil in April, the engine starting smoking. I may have overfilled the crankcase. Now I have to add oil after every cut. When cranking, a huge amount of black smoke blows out the exhaust. During mowing a small amount of bluish smoke is emitted. No trouble starting or mowing, except that I notice a decrease in power when encountering higher grass/weeds. Is it the carburetor or rings on the piston? How much is this going to cost to have a professional repair it? TIA
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.
#11
B
bertsmobile1
B
bertsmobile1
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 floodingYour 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.
#12
S
slomo
S
slomo
LOLYour 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.
#13
OzPete
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.
OzPete
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.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
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.
#14
Scrubcadet10
Scrubcadet10
blown head gasket won't allow fuel into the crankcase.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.
#15
B
bertsmobile1
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 .
B
bertsmobile1
Inteks do eat head gaskets but the ratio of failed float vales to blown head gaskets would be around 20 :1 in my workshop.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.
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 .
#16
OzPete
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.
OzPete
Original Poster mentioned that he had BLUE smoke emitted, and some loss of power in-the-cut.blown head gasket won't allow fuel into the crankcase.
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.
#17
Scrubcadet10
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?
Scrubcadet10
and when cranking it blows it black smoke.....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.
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?
#18
Z
zippy2
Z
zippy2
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.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?
#19
sgkent
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.
#20
Z
zippy2
Z
zippy2
This makes sense!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.
#21
S
slomo
S
slomo
Stop using the mower.
Fix the carb. Pressure test the needle and seat to 7psi. Should hold for 30+ minutes with a WET needle. If not get a rebuild kit or a new OEM carb. Stay off Amazon and Ebay for carbs.
Once the carb is fixed, dump the oil a couple times PRIOR to mowing.
Fix the carb. Pressure test the needle and seat to 7psi. Should hold for 30+ minutes with a WET needle. If not get a rebuild kit or a new OEM carb. Stay off Amazon and Ebay for carbs.
Once the carb is fixed, dump the oil a couple times PRIOR to mowing.
#22
K
Knocking Oppy
K
Knocking Oppy
float leaked gas into the motor oil, thinned it ... big time . gasoline is not a lubricant. lucky if didnt spin weld the rod to the crankshaft... spin/friction welding. they put tool joints on drill pipe that way. tool joint, M or F end, is machined. pipe is made in plug mill. pipe is held. machined tool joint made up in fixture, spun at high speed and the 2 shoved together... friction welding. excess mushroom is machined off... x rayed for flaws and good to go.
some ppl put a fuel shut off valve in the fuel line and at the end of the day shut the valve off and let the motor / carb run out of gas... DONT FORGET TO TURN THE KEY OFF OR WILL DRAIN THE BATTERY!!! got to remember to turn the fuel on before starting the motor.... hopefully, will figure that one out before running the battery to nothing. battery maintainer makes batteries last a good long time... sometimes.
write on the dash with marker (its not a lexus/mercedes, its a mower) TURN ON GAS TO START.. TURN OFF GAS AT END OF DAY. .. let carb run out of gas and TURN KEY OFF.
the problem is worse with the gas tank above the carb as gas will "gravity" thru the leaking needle/seat in the carb and keep "gravitating" thru the carb til... the crankcase is full and the gas tank is empty. that will leak to thrown rod in horizontal motor as it is an air pump. NOT A FLUID pump. overfilling engine with oil will blow it up, dont ask. thank you. change oil on LEVEL GROUND AND NOT IN THE DARK. simple enuf. (sigh) lessons learned.
oil change might prolong its life...20-50 oil... with ~25% STP OIL TREATMENT to thicken the oil. most ppl dont use mower in winter so dont need 0w-20 for those MINUS 20* morning starts. black smoke is excess gasoline/burning RICH. blue grey smoke is oil burning.
i have problems starting my little push mower, primer bulb never did work right, even new. so i got 500 ML RC Gas car/truck/truggy fuel bottle, take off air cleaner, dribble gas in the carbs throat, put air cleaner back on... starts 2 pull... not 5000th pull or i have heart attack/stroke/fall over...curb it, whichever occurs first. a big puff off BLACK SMOKE out the exhaust and away it goes.
CHECK OIL BEFORE EACH RUN OF DAY sticker on E bay. actually CHECK OIL BEFORE STARTING to put on prominent place on machines as most ppl just cannot do it and... i get them. too worn out to rebuild, but i rebuild them anyway just to see if i can do it. they run but ... 60 PSI running compression, not 110-130 PSI ? Model T ran on ~60 PSI running compression... 4 to 1 compression ratio... down on power, but will run the cheapest gasohol and not worry abt pre ignition.
my latest Briggs rebuild... scored cyl/piston from... no oil changes... no oil? sanded cyl/piston skirt, cleaned it out, new rings (shd have replaced rod but it seemed ok?). new gaskets/seals off e bay. piston rock in cyl is noticeable. 15-40 wm diesel oil started/runs ok... PISTON SLAP from piston wobbling around in cyl as piston/cyl is worn (out). 20-50 oil with 30% STP oil treatment... still big time piston slap. sounds like rod knock but isnt. might last... ??? it will foul the plug with oil so will have to clean plug or put in new ones from time to time as the plug gets coated with oil and wont fire. $3 plug at WM. it will run til it wont and that will be that. 50 hrs of limited use?
read can use up to 80% LUCAS oil stabilizer (liquid grease) in motors and differentials/transmissions/xfer cases for BADLY WORN machines??? ok for warm weather machines as LUCAS/STP is still fluid above... 40*F? below 40*F? need 5 mins to get the liquid grease to be more fluid.
some ppl put a fuel shut off valve in the fuel line and at the end of the day shut the valve off and let the motor / carb run out of gas... DONT FORGET TO TURN THE KEY OFF OR WILL DRAIN THE BATTERY!!! got to remember to turn the fuel on before starting the motor.... hopefully, will figure that one out before running the battery to nothing. battery maintainer makes batteries last a good long time... sometimes.
write on the dash with marker (its not a lexus/mercedes, its a mower) TURN ON GAS TO START.. TURN OFF GAS AT END OF DAY. .. let carb run out of gas and TURN KEY OFF.
the problem is worse with the gas tank above the carb as gas will "gravity" thru the leaking needle/seat in the carb and keep "gravitating" thru the carb til... the crankcase is full and the gas tank is empty. that will leak to thrown rod in horizontal motor as it is an air pump. NOT A FLUID pump. overfilling engine with oil will blow it up, dont ask. thank you. change oil on LEVEL GROUND AND NOT IN THE DARK. simple enuf. (sigh) lessons learned.
oil change might prolong its life...20-50 oil... with ~25% STP OIL TREATMENT to thicken the oil. most ppl dont use mower in winter so dont need 0w-20 for those MINUS 20* morning starts. black smoke is excess gasoline/burning RICH. blue grey smoke is oil burning.
i have problems starting my little push mower, primer bulb never did work right, even new. so i got 500 ML RC Gas car/truck/truggy fuel bottle, take off air cleaner, dribble gas in the carbs throat, put air cleaner back on... starts 2 pull... not 5000th pull or i have heart attack/stroke/fall over...curb it, whichever occurs first. a big puff off BLACK SMOKE out the exhaust and away it goes.
CHECK OIL BEFORE EACH RUN OF DAY sticker on E bay. actually CHECK OIL BEFORE STARTING to put on prominent place on machines as most ppl just cannot do it and... i get them. too worn out to rebuild, but i rebuild them anyway just to see if i can do it. they run but ... 60 PSI running compression, not 110-130 PSI ? Model T ran on ~60 PSI running compression... 4 to 1 compression ratio... down on power, but will run the cheapest gasohol and not worry abt pre ignition.
my latest Briggs rebuild... scored cyl/piston from... no oil changes... no oil? sanded cyl/piston skirt, cleaned it out, new rings (shd have replaced rod but it seemed ok?). new gaskets/seals off e bay. piston rock in cyl is noticeable. 15-40 wm diesel oil started/runs ok... PISTON SLAP from piston wobbling around in cyl as piston/cyl is worn (out). 20-50 oil with 30% STP oil treatment... still big time piston slap. sounds like rod knock but isnt. might last... ??? it will foul the plug with oil so will have to clean plug or put in new ones from time to time as the plug gets coated with oil and wont fire. $3 plug at WM. it will run til it wont and that will be that. 50 hrs of limited use?
read can use up to 80% LUCAS oil stabilizer (liquid grease) in motors and differentials/transmissions/xfer cases for BADLY WORN machines??? ok for warm weather machines as LUCAS/STP is still fluid above... 40*F? below 40*F? need 5 mins to get the liquid grease to be more fluid.
#23
sgkent
sgkent
yes. Having the carb rebuilt professionally would be wise too. As to the remark someone made on the head gasket. You can have more than one problem causing grey smoke, so if fixing the carb doesn't solve it completely have the head gasket checked too. I find that the heads on all the air cooled equipment I have owned need to be checked for torque once in awhile.
#25
Z
zippy2
Z
zippy2
So I replaced the carb with an OEM B&S. Still smoking. Must be the head gasket? If so, I'll have to get a pro to repair as I am not capable of doing it.
#26
S
slomo
S
slomo
Is this an Intek engine? If so they love to toss some head gaskets.
Might post up your engine numbers.
Might post up your engine numbers.
#27
B
bertsmobile1
A first timer should allow a full day
Techs do them in about 1 hour , the total scheduled service fee for the job is just short of 1 hour
I charge out 2 hours regardless of how long it takes
The gaskets are not expensive and the only special tools needed are a small tension wrench because the bolts are tightened to around 25 ft lbs and a sheet of glass with some wet & dry about 400 grit .
B
bertsmobile1
You are capable of replacing the head gasket it is an easy jobSo I replaced the carb with an OEM B&S. Still smoking. Must be the head gasket? If so, I'll have to get a pro to repair as I am not capable of doing it.
A first timer should allow a full day
Techs do them in about 1 hour , the total scheduled service fee for the job is just short of 1 hour
I charge out 2 hours regardless of how long it takes
The gaskets are not expensive and the only special tools needed are a small tension wrench because the bolts are tightened to around 25 ft lbs and a sheet of glass with some wet & dry about 400 grit .
#28
Z
zippy2
Z
zippy2
Is this an Intek engine? If so they love to toss some head gaskets.
Might post up your engine numbers.
It's a Platinum series. Hauling it off today to a pro.Is this an Intek engine? If so they love to toss some head gaskets.
Might post up your engine numbers.
#29
Z
zippy2
Z
zippy2
Thanks for the encouragement, but I'm hauling it off today to a pro. I don't have any of the specialized tools necessary for the job.You are capable of replacing the head gasket it is an easy job
A first timer should allow a full day
Techs do them in about 1 hour , the total scheduled service fee for the job is just short of 1 hour
I charge out 2 hours regardless of how long it takes
The gaskets are not expensive and the only special tools needed are a small tension wrench because the bolts are tightened to around 25 ft lbs and a sheet of glass with some wet & dry about 400 grit .