Briggs & Stratton Blowing Smoke

[enginemagician]

When they fail with gas/oil mixture like they described the smoke billows out like a freight train.

 

[Joed756]

generally if the needle fails while the tractor is sitting, fuel flows into the intake and combustion chamber and past the piston rings,

Now, i will say i repaired a Kohler CV15 a few weeks ago, gas dripping out of the muffler.... needle failed and drained the entire gas tank, and i don't know how, but i checked the oil, the oil level was perfect, not diluted and didn't smell of gas..
how it didn't get past the piston rings, i don't know. however i did change it out to err on the side of caution, and it needed it as it was pretty dark./old.

Wouldn't that happen with the exhaust valve open, creating an easier path than around the rings?

 

[Joed756]

You might also want to check for obstruction in your crankcase breather.

 

[slomo]

I watched the video again. No way a carb needle can do this. Smoke color was a tremendous blue/white smog.

Carb needle flooding the cylinder would be blowing black smoke, chugging all the time. Just like running it with the choke on but way more severe.

slomo

 

[Scrubcadet10]

unless the needle failed and raised the oil level.

 

[Born2Mow]

unless the needle failed and raised the oil level.

Correct !! But...

The float needle does not need to go "bad" for this to happen. There could be a bit of trash in the fuel system holding the valve open. Either way you'd get the same result.

I must type this 15 times a week.... You need to install a fuel filter to remove all the trash in your fuel. Then you need to install a manual fuel ON/OFF valve so that GRAVITY doesn't push gasoline into your engine when you're not looking. This happens all the time.

If this Board was worth a toot, there would be a directory full of these specific explanation articles so that we could simply say, "Go read number 15 and 17." And be done with it. The board would make just as much money and the customers would be better served. Apparently someone is more worried about the money than the customer service. That is extremely short-sighted.

 

[Boudreaux In Eunice La.]

I watched the video again. No way a carb needle can do this. Smoke color was a tremendous blue/white smog.

Carb needle flooding the cylinder would be blowing black smoke, chugging all the time. Just like running it with the choke on but way more severe.

slomo

I agree with the people that are saying NEEDLE , Or there is some varnish / gum build up on the seat. those VITON tips on the needles are etho proof so says the company......... A combo of seat and head gasket is suspect.....

Hello to all my ole friends here on the forum !~! Later from Cajun Country......

 

[randyjoe]

I put a new B&S engine (INTEK 17.5 HP - Model 31R907-0006-G1) on my Snapper riding mower 3 years ago. All running great until today when it started BLOWING SMOKE..... a lot of smoke. Pulled the oil dip stick and smelled of gas. Changed the oil and blew a small amount of smoke on first start. Second start had no smoke and runs smooth. Any advice on what's going on here. Here's a link to a You Tube 20 second video showing what's happening:

It’s definitely your needle or seat, I’ve had mowers come into my shop with the same problem many times

 

[randyjoe]

It’s definitely your needle or seat, I’ve had mowers come into my shop with the same problem many times

Be sure to check the float also, it should not have any gas in it, shake it to make sure, if gas got in you have a crack in your float which will not let it float correctly and set the needle in the seat

 

[footballfan33]

Yeah unfortunately these are pretty junky engines. Camshafts love to come apart and yes head gaskets like to blow too. The Nikki carbs are a PITA. Hard to work with and fail a lot. I try and find Walboro replacements when available, or I buy aftermarket eBay carbs. No sense in spending 120 bucks on OEM when they’re leaky low quality anyway. Ethanol is known to deteriorate rubber, and the Nikki carb has that giant o-ring thingy as well as a needle seat made of rubber. I have seen what ethanol can do so I avoid it personally, whether or not it’s the sole cause of carburetor failure. Could be entirely wrong but non ethanol gas is only a bit more expensive so no harm done.
But in OP case, the oil smelling like gas and being too full before changing, and the fact that changing it solved the problem (for now), that basically guarantees his problem is needle and seat.

Where can we purchase non-ethanol gas? Second question: Is stabilizer necessary for non-ethanol gas stored in gas cans for 1-3 months?