I have a two year old 21HP Briggs motor on my mower, and it just started smoking, idle, or under load. When applying a load from the deck and blower (bagger) I get a heavier smoke for a moment.`
Could this just be something that I need to add a fuel cleaner to clean a dirty valve or something? I hope. Any suggestions?
A additive can’t hurt I don’t think. The good news is I’ve seen those things belch smoke for many, many years before they finally croak.
have U check the air filter? 
checked or change oil – smell it 4 gas – if like gas change again – might have a neeldle or float issue
can just shut off gas and run it empty each time U use it – till u find a fix
this should help 
I’m with IGO. I wouldn’t automatically assume that where there’s smoke, there’s burning oil.
Questions:
1. Have you ever checked or changed the oil on this mower? You don’t mention having checked the oil level, so what’s it like? Is it low?
2. How much oil, if any has been consumed since you last checked it?
3. If you’ve changed oil recenetly or had it done, what oil are you running? You should be using SAE30, NOT multi-weight and certainly not low vis multis like 5W-30.
4. Do you have extensive hillsides on your property?
There are lots of potentional things that could be the issue here. I’d start by looking at the air filter and doing a good carb clean.
Obviously, if you haven’t changed the oil, you should do so. You should be checking oil before every use so you can know if there is oil consumption.
Grouse
Not sure if that model Briggs has a crankcase breather or not, if it does being plugged will/may cause smoke.
Al
Thanks guys. Change oil every year (30wt), and odd it doesn’t seem like it is burning any. Oil seemed good. Will look at filter again, and look for the breather (Briggs). This is a new motor put on a mower that blew a motor after seven years. The bagger has a blower, and adds a lot of drain on the motor no doubt. That and some grade on the lot. This is a bigger motor I put on to off-set the bagger…. all this is in factory specs as it is a factory bagger/blower. I’ll check the little things mentioned.
What color smoke?
Isn’t oil usually white and to much gas black???
Al
Probably needs new plugs. My rider started smokeing some and I pulled the plugs and they looked black and carboned up. Put in new plugs and it runs like new. Also check fuel and air filter but Im betting new plugs will solve the problem. Wouldnt hurt to add a little sea foam etc. to a tank of gas.
One of my favorite things about IDO…. a place you can go and have a good discussion, and ask for help on a wide variety of topics…. the fishing stuff is great, all this is a big plus.
Smoke is white.
I will take advantage of all the suggestions.
Quote:
What color smoke?
Isn’t oil usually white and to much gas black???Al
No.
Usually burning oil is a blue colored smoke and it leaves a greasy residue.
Too much fuel produces a black smoke.
White smoke most often is a result of leaking coolant or water into the cylinder from a head gasket. But that’s a liquid cooled engine, obviously. No idea what’s going on if you’ve got white smoke coming out of an air-cooled engine. Only thing I can think of is massive water contamination of the fuel OR is there some way that water is getting inside your exhaust system? For example, is the tractor sitting outside?
If this mower isn’t consuming any oil AND assuming this isn’t liquid cooled, I’d say look at fuel system issues first.
Change the plugs and make sure the gap is right, clean the carb, and personally I’d look up the factory settings for the carb and then check them against the current settings to make sure a needle hasn’t been vibrated into a wide open position or nearly so.
I’d also be tempted to drain the gas tank and refill with fresh fuel. I always like to completely eliminate the chance of contaminated fuel, even if it seems unlikely. You just never know when something happened like the kids deciding that dad’s mower would enjoy a can of Diet Coke.
Grouse
Ethanol is the culprit. 
Quote:
Ethanol is the culprit.
Would you recommend he use a transom saver to prevent ethanol damage?
Grouse
Really????????? We are suppose to check & change oil on a lawn mower? Crap, another thing I’ll catch he77 for not doing. 
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