Lawn mower smoking? Reasons why and how to fix it!

In this video I go over the most common reasons why lawn mowers smoke. The color of the smoke is an indicator of the problem. There are several reasons why lawn mower engines smoke. Some are more serious than others.
The most common reasons also are the easiest to fix!
Here is a link to the fuel pump video I previously made. • How a $30 part can des...

[@Mechanical_Mind]

To find tools, shop equipment, mower parts and more, you can find them at my store. Click this link: www.amazon.com/shop/mechanicalmind I'll get a commission on the sale at no extra cost to you. It's a great way to help the channel and get the items you need.

[@philliphall5198]

Hard to find any good repairs jobs but you did a great job of explaining it

[@Theultrazombiekiller]

Mine was the carb. Engine was getting flooded on my JD lawn tractor and would smoke like crazy when it started. I removed the spark plug and about a pint of gas poured out of the combustion chamber through the spark plug hole. The crank case was filled to the top with gas and the oil was super diluted. Turns out the carb was getting stuck open and so when it was not running, gas was just filling up the entire engine. I put a new carb on it for $25 off amazon and a fuel shut off valve to make sure it does not happen anymore. Runs fine now.

[@Mechanical_Mind]

Good call! I see that often also, but usually the customer complaint is the engine will not start (due to a cylinder being filled with gas). If the engine does start and I see gas shoot out of the muffler I know it's the carb. Sometimes it's just the fuel shut off solenoid stuck open from gunk. Bad part is that many times a nee solenoid alone is nearly as expensive as an entirely new carb with new solenoid included.

[@integritynow1]

You just answered my question. Thanks!

[@mikerossman9863]

Same thing on my old Troy Built Pony. I just put a manual shut of valve on the fuel line. It eventually would not start because I thought the valves come out of adjustment, but wasn’t it, so I just got a bigger amp battery. It finally give up the ghost when the transmission wouldn’t go forward😞 this only took about 1 and a half years… mind the deck kept throwing belts off too🤬

[@michaelbradford4444]

I like the way you share information , direct without rambling on about personal ways in witch you choose to do the work and ... that you don't come off like a lot of these self thought experts who know everything not realizing that most people viewing are not complete idiots! Ty from your newest subscriber.

[@Mechanical_Mind]

Thanks Michael!

[@jonathanbadillo8243]

Keep doing videos like this bro you help me out fix my problems of my zero turn 😅😂💯

[@travel_eR.]

Thank you for the clear explanation... After work I need to check my JD riding lawnmower. Misses said it smokes like crazy when started.

[@Mechanical_Mind]

Does the smoke clear up after a few seconds? What color is the smoke?

[@travel_eR.]

@@Mechanical_Mind yes and white

[@Mechanical_Mind]

@travel_eR. It might be just over filled a little on engine oil. It's actually pretty common to see them smoke a second or two at start up.

[@alexanderzayas8213]

Awesome video. Watched this for my weed eater

[@robertmailhos8159]

The other thing is that make sure to be on a level surface for making sure that you get a proper oil level reading

[@kahunaal1631]

Good advice and direction. Thanks.

[@moesauto]

On the topic of the fuel pump failure.. I heard someone else say the underlying cause for the fuel pump issue is a failing head gasket that over pressurizes the fuel pump damaging the diaphragm

[@franwebb7756]

Shared, will help some folks with mowers this Spring and Summer.

[@rickraub5448]

Just happened to me. Major Kiss concert in my backyard. I had just added oil thinking it was low. Not a clear oil line in dip stick. Kind of streaky and not a definite line. Will drain some and try again. Thanks for the thought.

[@Mechanical_Mind]

Check this video out as well. kzbin.info/www/bejne/iH6ofnSJrKtqms0. Your fuel pump could be letting gasoline into the engine oil and overfilling the crankcase. That also might be why your oil line was hard to read (mixed with gas), and also, it might be why it started smoking.

[@rickraub5448]

@@Mechanical_Mind Thanks. I drained some oil out and it’s fine now. Thanks for the advice. Saved me a trip to the mower shop

[@keithrayeski6417]

New subscriber….I’m dealing with a smoking Husqvarna 775ex and I’m thinking too much oil but, no drain plug. So I’m working on a method to remove some oil without turning it on its side…which probably would not hurt it. But your video helped me confirm my thoughts and eliminate other possible failures. I’ll check out your other stuff. 👍🏻

[@Mechanical_Mind]

Get a pump extractor to remove the oil. It will make changing the oil much easier and cleaner.

[@RiseOrRelinquish]

Hi, mine is still smoking, white smoke. It's a poulan pp19a42 with a briggs 19 hp. Oil level is okay. Changed spark plug, fuel filter, oil filter, and air filter. I will check the compression next. What should it generally be? Nice video

[@Mechanical_Mind]

Was the oil level too high before you changed the oil? It could be a head gasket, or valve seal leaking. Even after it's fixed there will be some oil in the muffler so it will smoke as it burns off that oil residue in the muffler.

[@RiseOrRelinquish]

@@Mechanical_Mind turned out to be the head gasket. I replaced it and the valve cover gasket. Checked the valves also. Started right up and not a single puff of smoke.

[@Rein_Ciarfella]

Another more common reason for smoking is debris under the engine shroud. Could be mouse nest or built up leaves, grass clippings, etc. The engine will run fine at startup but as soon as it heats up enough then the combustibles will start to smoke. This is dangerous for two reasons. The main reason is engine overheating, which can destroy an engine. The other is an engine fire - less common but just as destructive.

[@DianeSchouviller]

Thank you for the video. My Ariens riding lawnmower is now running great, because of your video. I thought I was going to have to replace it. So, Thanks again.

[@strangerintown3676]

My Husqvarna riding mower was smoking big time. I'm pretty sure it had to much oil, so I changed it & it was ok. 2 weeks later started it up it again smoked big time. That was the last time I would have used it as grass cutting season is over. I'm not sure what to do, but mower has full tank of gas, maybe I should start it & let it run to see if the smoking stops.

[@Mechanical_Mind]

If the muffler has gotten full of oil residue it will take awhile to burn it all out. Hopefully that was the only issue

[@strangerintown3676]

@@Mechanical_Mind Thank you for the reply, I will give it some run time monday.

[@robinmoore5115]

Great video, thank you so much!!!

[@rosalbaorellanp4842]

Question so if this happens just change the oil ? Or le it burn that oil ??

[@cliftonhead9665]

I look through your videos and couldn't find anything like the problem I am having. I have a Cub Cadet 46" RZT L with 190 hrs. The mower will start at times and works great. Other times it want start as if dead battery, battery is good btw, can't hear anything when trying to start the engine. Example: Cutting grass and stop the mower to take a break return starts right back up no problems. Then another time after stopping when I return no start. Go back in and after mower sets awhile or sometimes overnight it starts. I do my own maintenance being a retired Navy electrician / mechanic. Any suggestion. Tks

[@Mechanical_Mind]

Have you watched this video? kzbin.info/www/bejne/g3KyhpJ8itKJaJo. Sounds like you have a starter solenoid that is going bad.

[@michaelhorstman2603]

I have a question for you about a rider that smokes but not like an issue you explained. This mower only smokes after it’s sat for a week and only on start up. After a minute it clears up and won’t smoke. Any ideas?

[@waltofalltrades6817]

That's what I was wondering, my mower does the same thing. If it sits for more than a few days, it smokes for the first minute or so after startup, then stops. If it only sits a day or two, it won't smoke at all. It only does it after sitting a few days or more, which is the part that's really got me stumped.

[@michaelhorstman2603]

@@waltofalltrades6817 I’ve found out it’s the carburetor needs cleaned at least with mine

[@waltofalltrades6817]

@@michaelhorstman2603 Thanks, I'll try that.

[@audreyeisenmann4812]

I have the same issue, have you guys discovered a solution? Thanks

[@michaelhorstman2603]

@@audreyeisenmann4812 mine was a gasket that was leaking a little oil into the exhaust.

[@popaki9484]

My weed eater is smoking bad! I installed new carburetor and spark plug but it smokes white after few min running. Can my oil have gas in it? Does my weed eater have a fuel pump? I have a craftsman thank you!

[@jamesbigham8365]

Not to mention the longer it is ran burning oil it will constantly burn oil fix the problem and conserve your oil!

[@rovertennessee]

Very informative video.

[@dwash595]

Great video. Thanks!

[@Mechanical_Mind]

Glad you liked it!

[@MrBRUCELEE98]

Would this be normal on a brand new mower? I just got a John Deere Z320m yesterday, ran it for about 20 minutes with no issue and then today it is smoking like crazy!

[@Mechanical_Mind]

I bet the valve cover gasket is leaking and dripping oil on to the exhaust. New ones come in with that issue all the time

[@MrBRUCELEE98]

@Mechanical_Mind Dang dude thank you! That is exactly what it was. You are the man👊🏻👊🏻

[@boudoirbyrdmimagery]

I changed my head gasket and it's now blowing Black smoke. When I took the spark plug out, there was oil residue on it. Is that a possible piston ring issue?

[@Mechanical_Mind]

Black smoke is usually too much fuel/ unburned fuel. Let me get a little more info.. You said you changed the head gasket and NOW it's blowing black smoke. Was it smoking before you changed the head gasket?

[@boudoirbyrdmimagery]

@@Mechanical_Mind it was blowing white smoke mostly since oil was dripping onto the exhaust. Now the engine is running rough even after I have adjusted the valves to the manufacturer settings and lots of black smoke. The spark plug has some oil residue on it , wasn't blowing black smoke prior to changing head gasket

[@Mechanical_Mind]

@boudoirbyrdmimagery With it running poorly and black smoke, it could be a carburetor issue. I'd double check the linkages are all hooked up properly. Also check for possible vacuum leaks around the intake manfiod gaskets and carb gaskets. The black smoke might be from it burning off the oil residue that got inside the exhaust prior to the new head gasket. Not sure if you changed the oil or not but I'd check the oil for signs of gasoline getting in the oil. The fuel pumps can go bad and start letting fuel into the oil and oil into the gas.

[@boudoirbyrdmimagery]

@@Mechanical_Mind I changed the carburetor and it stopped smoking so the smoking issue is fixed. Now it's backfiring at times, I have the valves set to intake .004 and exhaust .006. Any other ideas? Fresh oil change, spark plug, new oil filter and air filter, belts etc

[@Mechanical_Mind]

What engine model is it?? First I'd check for vacuum leaks around the carb by spraying some carb cleaner around the new gaskets. And there are times where a new carb out of the box has issues. I'd double check the valve clearance. I always rotate the engine over a few times then recheck the settings. Normally on the engines I work on the valve specs range from .004 to .006 for both valve so I'll shoot for .005 and after double checking if this with in that .004 to .006 range I leave it alone. If all that is good I'd do a leak down test to see if the valves are seating properly. You also could have a broken key for the flywheel causing the timing to be off a little but that is rare.

[@BigRockHorseRanch]

I have a brand new 0 turn John Deere that won't start. It started for a bit and had white smoke and now won't start again. Any ideas?

[@Mechanical_Mind]

kzbin.info/www/bejne/g3KyhpJ8itKJaJo

[@christianvasquez8228]

Porque mi zero turn toro echa mucho humo por el mofle

[@rebeccaedwards8262]

Good video

[@boritzkirw]

Check to see if the fuel looks blue.

[@B.Weedster]

My problem is I was mowing. Apparently my lawn sank from an old tree stump rotting away from 35 yrs ago. So I ran into the dirt in my yard a few times trying to get out of hole. What would be the result from the mower slamming into the side of hole. Hope u understand what I meant. I hope I didn't Crack the head gasket.

[@user-hg5xh7io1b]

Very helpful video 👍

[@frankcosta1932]

Would this happen with a mechanical fuel pump as well? My John deere has all those symptoms but has a mechanical fuel pump instead.

[@Mechanical_Mind]

It could. Does your engine have gas in it? Here is a video showing a trick to see if your engine oil has gas in it. kzbin.info/www/bejne/iH6ofnSJrKtqms0

[@cazadordepennystocks3408]

I would like you to give me an answer if possible I have a john deere z915B that is burning a lot of oil it does not loose power but it uses about 1/2 quart every hour it only smokes a little after it has been working for more than an hour

[@FishFind3000]

If it’s not smoking then it’s not burning it. I’d look for a big leak somewhere. It could be the output shaft seal and could be leaking right under the engine onto the ground without you noticing.

[@baklash1762]

A little bit confused on this subject. My pressure washer has not been used in over a year. Started to pressure wash the driveway; started right up, seems to run ok, but after a minute or so it starts emitting black smoke; not white, not blue. Was afraid to continue. It doesn’t have a dip stick, just a plug on each side. Air filter looks good; it’s just a foam pad, no pleated paper. Since black smoke indicates unburnt fuel is there a danger to the engine if I temporarily proceed long enough to do the job and try to solve the problem later?

[@Mechanical_Mind]

It might be the carb is minda gummed up from sitting so long. Try installing a new spark plug and fresh gas with some fuel addictive like Lucus fuel treatment. Then use the pressure washer for a good 20-30 mins to see if it clears up. If it doesn't clear up Id bet you need a new carb.

[@baklash1762]

@@Mechanical_Mind Thanks for the prompt reply. The fuel has a treatment in it that I added when I last used it. I think that’s why it started so easily. I’ll check the spark plug first thing tomorrow. Now that I think about it, I believe the manual may have said to add a little oil to the foam air filter. I would have done it a year ago also. Also wondering why it doesn’t have a typical pleated paper filter. Washer is over 14 yr old, and has a Subaru engine. I was surprised about that when I bought it new. Thanks again.

[@philliphall5198]

Bought a pressure washer dirt cheap that was smoking really bad Had 2 cycles oil in it and the 4 cycles don’t like it

[@Mechanical_Mind]

Yeah, Ive seen that too. It shouldn't hurt anything. Seller probably thought it had bad rings. 🤣

[@robwright4398]

I have a opposed twin Briggs that shows to much oil but after I run it and it’s where it should be. Why is it like that?

[@Mechanical_Mind]

Your fuel pump is probably allowing gasoline to enter the crankcase. Here is a video I did explaining that in more detail kzbin.info/www/bejne/iH6ofnSJrKtqms0

[@chris2345]

Hello, I just replaced the drive belt on my John Deere 1542hs and it was running fine. I drove it twice up and down my lawn and it made pop sound with white smoke and stopped suddenly. What happened to my lawn mover?

[@Mechanical_Mind]

Is the white smoke coming from the engine or the new belt? Did the new drive belt break?

[@chris2345]

The engine, all around the cover

[@Mechanical_Mind]

@chris2345 Popping noise and engine stopping suddenly is never a good thing. I'm guessing you have some internal engine damage. It's kinda hard to know for sure without inspecting it in person. If you want you could email me some pictures to [e-mail] and I'll try to guide you along to figure it out.

[@chris2345]

Ok

[@maxrockatanksyOG]

Currently having to deal with the local Cub Cadet dealer as my XT1 L42 is blowing therough engine oil. Dwaler is saying its lack of air filter maintenance (despite it gets a new air filter every 25hr servics- currently on 90hrs); they are arguing the ride on shouldnt be used in a dusty enviroment- wtf? (Because of the cheap and half arsed designed air intake system, dust gets in and has scores the bore- requiring a new engine ($1520 AUD) or a rebuild ($820 AUD with 12 week wait on parts). Waiting to hear about warranty, and will build my own intake system with proper dust seperation with Donaldson filter

[@Mechanical_Mind]

Im assuming they did a leak down test to determine the oil consumption is from worn piston rings. If so what was the percentage of leakage? Id also expect pics of cylinder wall scoring as additional proof it caused by dust. Intake design would not have anything to do with dust getting past the air filter.

[@codyphillips1082]

So im on here about my mower but u said something about the gas and oil miixing and so my question is i have a generator i got year ago and it did and does start but i killed it and rechecked the fluids (oil) and i noticed that it smelled like gas bad know i have poured the oil out and poured some through it and refilled and it seemed cool so started it again well i killed it and checked again and it had a slight gas smell again so if possible i need some advice lol

[@Mechanical_Mind]

It's important to cut the fuel off with the fuel shut off valve when the engine is not running. Also, your fuel shut off valve could be bad, letting gas pass by it even if it's closed. When gas is allowed to gravity feed to the carb it can easily leak into the engine cylinder, past the piston rings and into the engine crankshaft case and mixing in with the engine oil. You can check to see if your shut off valve is leaking by removing the hose past the valve going to the carb and see if gas is dripping with the valve closed. Some gas will be in the line so let that dry up / wipe it up and see if it's dripping after several minutes

[@codyphillips1082]

@@Mechanical_Mind alright i will check that out and ill let u know and thanx thatll give me a start

[@ericaviator8869]

you forgot possible leaking VALVE cover gasket onto muffler

[@ATVProven]

My Ego mower smokes like that too. Can't find the dipstick on it to check the oil 🤔

[@Halenrocks5150]

Isn’t your EGO an electric mower?

[@Rachel47277]

Will it smoke if the oil is too low?

[@Mechanical_Mind]

Yes, if the engine has been running for too long with too low of oil, it will cause damage to the engine that will cause it to burn oil and smoke.

[@Rachel47277]

@Mechanical_Mind thank you for th3 reply. Hopefully no damage done. Seems to be running good now.

[@boritzkirw]

I see almost as many times that they put 2 cycle fuel in the tank.

[@macknumber9]

Kinda looks like Eli Manning for a second

[@viralvideostrending5782]

💯🔥🔥

[@QuynhNguyen-vf2eo]

your video don't help me at all, if you come to my house and make my mower starts that will help

[@moesauto]

Bro solve your own problems if you can’t get an idea of what to do from this video then you are mechanically DECLINED

[@andrewwhite3377]

Amazing comment

[@RickyLangford]

Great job

[@RickyLangford]

Great job

[@superdad9886]

You can't just watch the video and it'll fix your mower you actually have to touch your mower

[@morejelloplease]

Mine used to smoke, now it just vapes lol. My FR691 in my scag liberty Z smoked just like this for 15 mins and filled my garage It would smoke lightly after that from time to time and no it was not overfilled or the engine was not tipped in a weird way. Reached out to the dealer and kawasaki, and I never heard back from them. It regularly consumed oil, about a quarter of a quart every few hours... I've owned several Kawasaki's and never had that problem. , the engine did this when it was brand new

[@BoneYardLawnService]

Good video