Small Engines (Lawn Mowers, etc.): B&S Engine blowing smoke, breather valve, blowing smoke

Question
QUESTION: Hi Eric,
The 14hp B&S engine in my garden tractor suddenly started blowing heavy white smoke out of the exhaust.
I removed and cleaned the breather valve, installed it with a new gasket but it still started smoking after less than a minute.
I bought and installed a new breather valve but had the same results.
I put some Seafoam in the cylinder overnight to see if that would help but it didn't.
What tests can I do to pinpoint the problem?
The engine model No. is: 320421, code 0134-01, type '71
The engine starts and runs fine and has all summer long until now. Any help you can give would be much appreciated.

Ray

ANSWER: What oil are you using?  Is the oil level correct?  Does the oil smell like gasoline?

Have the valves or valve guides ever been serviced/replaced?  Have the rings or piston ever been replaced?

That's a pretty old engine but you did the right thing starting with the breather.  

Let me know the answers to the questions above.

Eric

---------- FOLLOW-UP ----------

QUESTION: Hi Eric,
The oil I've been using is 10w-30 because I use the tractor with the 42" snow blower (which I had just put on) and since we have three tractors to maintain about 4.5 acres, I make sure I check the oil every time they get used.

The engine has an updraft carb. so gas is not leaking into the engine.

I have not replaced the valve guides but I did put in new valves, piston and rings in 1995. I did so only because at the time I was working at a hardware store and had access to the tools I needed and got a discount on the parts.

It's an old engine but a real workhorse. Accept for a few carb. rebuilds and batteries it has served me well summer and winter.

I forgot to mention that when I start the engine and take off the air cleaner, oil will start spitting out of the breather hose and into the carb. Eventually the oil gets sucked in and then the smoke begins.

Parts are getting hard to get and it might be cheaper to just replace the engine but I haven't been able to find a cross reference anywhere but I'll keep looking.

Hope these answers help.

Ray

ANSWER: Have you checked the valve gap and does the valve breather have a round disc inside it?  If it has the round disc the valve breather should rattle when you shake it.

The old school book answer was to never use multi-viscosity oil in Briggs engines.  Things, engines and oil have changed so it's difficult to say what the right answer is.

Have you ran 10W-30 before in this engine?

Let me know what the valve gaps are.

Eric

---------- FOLLOW-UP ----------

QUESTION: Hi Eric,
I set the problem aside for the holidays. Now that it's cold outside,I decided to give the tractor to my retired engine mechanic friend who has a heated workshop. I'm getting too old to work out in the cold.
To answer your questions, my friend checked the valve gaps and they were within specs. The breather valve is new and I've been running with 10w-30 oil for the last seven or eight years.
My friend pulled the engine,honed the cylinder and put new rings in. He commented that the old oil rings were a little tight but everything else looked good.
He then had it run for about 20 minutes and it didn't smoke. Then he drove it up the hill of his driveway and it started smoking again.
So that's where we're at as of today. You could earn your wings on this problem. Hope you can help us out!

Ray     {:^)

Answer
Was the oil scraper ring wore?  Are the rings chrome or standard rings?  Chrome rings have a tendency to seal better reducing smoke.

Does the engine have an oil fill plug or an oil fill dipstick tube?  

Do you have access to a cylinder leakdown tester?

Do you have a manometer to check engine crankcase vaccum?

Does the engine burn enough oil that you have to add oil everytime you use it?

Let me know.

Eric