Please advise - Do I need a new lawnmower?

I purchased my Briggs and Stratton 4.5 craftsman, push mower in 2006. Although not a mechanic, and a woman, have babied it - kept it tuned, good gas, gas stabilizer, cleaning air filter, changing oil often. Even had a mechanic friend completely take it apart, down to each screw 3 years ago, when the carburetor was clogged. (Traded him for a huge steak dinner :- )

The lawn mower ran like a champ until a few mows ago - started blowing significant white smoke, but ran fine. Is also using oil about 2-3 ounces with a 40" mowing time. Using Briggs SAE-30 and high test gas. Just read from a commenter on a youtube video to smell the oil, which I just did, and yes it smells like gas.

Is there anything I can do, or is this a blown head gasket? If it is something simple I can fix, then I can do it, but if complicated like cleaning the carb again, will just buy a new lawn mower. It still runs great, but may die soon. No longer in contact with my friend, so can't rely on him to fix it.

The only thing I can think of that may have caused this is that the screw or screw hole that holds the air filter and compartment got stripped and so I duct taped it as securely as possible, but last mow didn't check it in the middle of the mow, and saw it was loose. Opened the air filter compartment, stuck a clean rag in there and tons of black gunk. Cleaned it as best as I could, cleaned the air filter, ran the lawn mower - still a lot of white smoke.

Thanks all! I really appreciate any help.

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OP ignored.

At this point in time your camera is your best friend.
Set it somewhere then take a photo of each & every part as you take them off.
Thus you have a photo book to put it back together
Somewhere on the engine is a set of numbers Model code serial
If you can locate them and post them we can be a lot more helpful.

Thanks! I have the owner's manual.

Model no. 917.388831

I am way to "unmechanical" to change the carb as other poster suggested. In fact, I don't think
it can be changed, but would have to be cleaned manually - which is way above my expertise, as I have looked
at youtube videos.

I could put seafoam in it......

Just can't figure out why it is burning oil.... so far still runs great, but I know I have problems ahead if I
don't do something. Wish this was a easy fix.

Thank you anyone who may have suggestions.

Berts....., I might add that the "gunk" in the air filter chamber looks greasy - oil lish. I had just cleaned and dried the air filter
before the last mow. It wasn't dust or dirt, but greasy grime. And some still way at bottom.

Blue (or white?) smoke indicates oil consumption. Black smoke indicates excessive fuel consumption (too rich). So if the smoke is not black, then it shouldn't have anything to do with the carburetor.

I don't know what kind of condition the mower is in but if you've had it that long, it might just be worth replacing the entire mower even if you were mechanically inclined.

I've offered several disabled push mowers to a guy I work with who works on mowers in his spare time and he says fixing up free push mowers are not even worth his time fixing and reselling. The only time he repairs push mowers is when people who bring them to him for repairs.

Opinions may vary but Briggs and Stratton are notorious for oil consumption after they get a couple hundred hours on them. I bet my 21 hp riding mower has less than 500 hours on it and it uses about a quart between oil changes (every 100 hours). I even replaced the head gasket on it (which was blown). In this case it was fouling the spark plug so I had no choice but the replace it. Every B&S engine I've owned burns oil. Kohler makes the best engines, in my opinion.

I used to have a Snapper tractor type with a B&S engine and for some odd reason it never smoked, leaked oil or fouled the spark plug but consumed a quart of oil every time I mowed (3 to 4 hours). Instead of putting brand new oil in it, whenever I changed the oil in one of my cars, I would just drain it into a clean pan, pour it into a jug and top the engine off before mowing. I did that for years until I sold it.

If your engine is not fouling the spark plug, I would just top it off with used oil and not worry about it.

Used engine oil will smell like gasoline even if the engine is OK. That's just normal. If the oil level is rising, that would indicate that the float valve is leaking and filling the crankcase with gas. But if you are having to add oil to the engine, then that's not the case.

You could also find a used mower for free (a the dump for example) with a good engine but cracked deck. Then transplant the good engine over to your good deck.

As much as replacement engines cost, and as much as replacement parts are, I'm not so sure if I would even rebuild a lawnmower engine. Back in the 1990s, I was going to rebuild a 12hp B&S engine that had seized. By the time I added up all the parts, I could have bought a new one! I usually easier and cheaper just to find a lawnmower with something else wrong with it.

My father gave me this old Yardman push mower. It has a good Honda engine on it and uses no oil. The plastic piece that raises the front wheels had broken and the part was $80. So I just leveled the deck and welded the bar to the deck. Otherwise If I didn't know how to weld (well somewhat), would have junked the mower.

amelie said:

Berts....., I might add that the "gunk" in the air filter chamber looks greasy - oil lish. I had just cleaned and dried the air filter
before the last mow. It wasn't dust or dirt, but greasy grime. And some still way at bottom.

Click to expand...

Push mower engines are very sensative to being tipped the wrong way which allows oil to get into the carb which makes them hard to start & blow white smoke.
If the oil ends up in the muffler it does the same thing, for quite a long while and James Bond would be proud of the smoke screen produced.

Same with oil level.
Too much oil causes oil to be pushed into the cab and again this will make the filter oily.

Again we need the engine model & type & Code numbers to be more specific.
There is a plain sponge filter which should be fitted dry with a finger wipe of oil on the top and can e washed & cleaned.
There is a paper element ( many different kinds ) which must be fitted dry and if it gets oily needs to be replaced.
There are foam prefilters fitted to some of the paper elements , some of which can be washed but some cant because they have wire inserts.

Turbo - very cool looking refurb job you did on the ugly! Nice.

I am inclined to try and fix my mower as I may not be living her next year, and so perhaps won't need a mower. Trying to
get one more season out of it. It's too dark/late now to check if the spark plug is fouled - will do tomorrow.
What will it mean if the plug is fouled? And can I just soak it in gas to clean it for now?
I used to own a Rabbit way back in the days. Bought it for $200.00 and the spark plugs would foul. Had to soak them in
gas every week and put them back in. Always knew when I needed to clean them, as huge white smoke billowed out of
the exhaust and it would stall and putter.

But my lawnmower is not puttering... it runs very smoothly as of now. Just lots of white smoke and burning oil.

And Berts - thanks for the clarity, will see if I can get the engine model no. tomorrow. The air filter is pure sponge - I wash
it out with Dawn really well and let it dry, but didn't know I was supposed to put a light coat of oil on top.

Thanks, guys, so very much.

amelie said:

Turbo - very cool looking refurb job you did on the ugly! Nice.

I am inclined to try and fix my mower as I may not be living her next year, and so perhaps won't need a mower. Trying to
get one more season out of it. It's too dark/late now to check if the spark plug is fouled - will do tomorrow.
What will it mean if the plug is fouled? And can I just soak it in gas to clean it for now?
I used to own a Rabbit way back in the days. Bought it for $200.00 and the spark plugs would foul. Had to soak them in
gas every week and put them back in. Always knew when I needed to clean them, as huge white smoke billowed out of
the exhaust and it would stall and putter.

But my lawnmower is not puttering... it runs very smoothly as of now. Just lots of white smoke and burning oil.

And Berts - thanks for the clarity, will see if I can get the engine model no. tomorrow. The air filter is pure sponge - I wash
it out with Dawn really well and let it dry, but didn't know I was supposed to put a light coat of oil on top.

Thanks, guys, so very much.

Click to expand...

Briggs tell you to oil them through then squeeze out the excess but what happens when you do that is the dirt clumps around the holes and chokes off the filter.
A old mechanic friend told me to just lightly oil the top and I have found it works a lot better so I have happy customers whose mowers work fine from one service to the next.

Modern fuel & modern plugs cause a lot of grief and you can not effectively clean a new plug, they have to be burned clean but for the price of a new plug it is a zero term game, just replace them .

Turbo - Berts - I think I may have found the problem - so asking either of you for advice.

Late last night, reading the owner's manual, I realized that I did something I have never done to this lawnmower in 13 years.
Don't even know why I did it on the last mow. It's true, it was formerly burning 2-4 ounces of oil with each mow, but not
plumes of white smoke continuously, like in last mow. And it ran before like a charm...so burning the oil didn't seem to be a problem.

I once owned an RX-7, and the word was on that car - (all RX-7's) that it burned oil naturally, so always had to keep an eye on it.
I even had a new engine installed, but still burned oil - I believe that was due to the dual rotary engine.

So what did I do to my lawnmower? I topped off the gas to the very very brim. Owner's manual says not to do that.

Haven't gone out to the shed to do anything with mower this morning, and friend is coming over at 11:00 am, EST, to help me with it.

Have a ruined the mower? And anything I can do now to remedy the gas top off problem. I am assuming even before I check on it, spark plug is fouled. Thanks, Berts, for the info about the spark plug. Won't try to clean it, but will buy another.