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Hello, I have a craftsman self-propelled mower with a B&S 7 hp motor. Last night, after about an hour's use, it started smoking terribly. Tons of billowing smoke. I figure a ring broke or something like that. Could excessive oil smoke be caused by something simpler? thanks shadester

Depends on what engine is on your mower. If it is an overhead valve engine, could be blown head gasket.

ILENGINE said:

Depends on what engine is on your mower. If it is an overhead valve engine, could be blown head gasket.

Click to expand...

MST is correct, as always.

I would also check the air filter for oil.
Did you happen to recently tip your mower at a sharp angle?
Assuming the oil level is correct or just a bit low.

ILENGINE said:

Depends on what engine is on your mower. If it is an overhead valve engine, could be blown head gasket.

Click to expand...

the model number of the engine is 128602-0212. I do not think this is an overhead valve model. there is no oil in the air filter and the oil level was fine before all the smoking.

If you are sure that it is not sucking oil, through air intake or breather, then it may simply have worn, etc. rings or more.

About how many hours (years) of use on it?

OHV motors have a characteristic valve cover (sheet metal or cast) on the head near the spark plug(s).
Flat head (L-head) motors have a flat or finned surface where the spark plug is on the head(s).

Here is a photo of an OHV motor, but not a Briggs.

Hello, I checked last night and found oil on the bottom of the air filter housing. The air filter is also very dirty, probably from mulching up so many leaves (i live in a very wooded area). also noticed a chunk of my blade was broken off (my reason for vibration). I removed the blade, took off the air cleaner and cleaned around it, and it started on the 3rd pull! Runs very rough but i'm hoping a good carb cleaning will fix that. No Smoke! Maybe this is still a keeper! The mower is used about 10 times a year about 2-3 hours at a time. It is probably about 15 years old. It doesn't have a valve cover, but the head is finned.
Thank-you for your ideas. shadester

Retiredcarguy said:

If you are sure that it is not sucking oil, through air intake or breather, then it may simply have worn, etc. rings or more.

About how many hours (years) of use on it?

OHV motors have a characteristic valve cover (sheet metal or cast) on the head near the spark plug(s).
Flat head (L-head) motors have a flat or finned surface where the spark plug is on the head(s).

Here is a photo of an OHV motor.

View attachment 20701

Click to expand...

Glad to hear the good news.
Yes, many big problems are caused by little things.
Keep a machine safe, serviced and clean, for then it will last a long time.

Hello again, over the weekend i took apart the carb, sprayed it several times with healthy doses of carb cleaner, blew air thru all the passages i could find with my air gun and reassembled. It idles better, but there is little or no change when i move the throttle. Everything on the carb seems to be connected and moving properly. I still have the air cleaner and the blade off. Just for giggles, when i put the old air cleaner back on, the engine dies almost imediately. I looked again and there is a cover over the head next to the spark plug (not finned like I thought, must have been good brownies!). Could this be a bad head gasket, a leftover problem from the original problem (tons of smoke, not many rpm's, lots of vibration)? I feel i am close, but it's not right yet. shadester

Sounds like a B&S OHV 7 HP.
Look for the model number on a data plate and Google it.
Does it stall when opening the throttle?
Does it run better when opening the throttle and squirting fuel in carb at same time?
Carefully, "very carefully," blow back through the fuel line to the tank, checking for good flow. Carefully...

Your air filter may have been completely blocked with dirt, debris and oil.
Buy a new replacement filter, if it is a paper type. Clean and re-oil, if it is foam and can be serviced.

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We moved your thread to the Small Engine & Mower Repair forum.