Outdoor Power Equipment and Small Engines - B & S 17hp Trouble

Scotts 17/42 mower, B & S 17hp I/C INTEK O/H Valve. M/N 311777, Type 0143-F1, Code 98111820.

Compression 100#. Under load, engine loads up and blows heavy blue/white smoke, especially when turning sharp. No load at full throttle produces no smoke. Engine starts and runs fine otherwise. Oil level (new) is on the money and new air filter. Plug was oily when comp check done and oil is present in the air box... also "coughs" oily smoke from intake when shutdown. Looks to me like the engine is going to have to come apart but still have my fingers crossed on a minor fix. Cam? Valves? Both? Rings? Etc? Thanks in advance for your advise.

OK...turns out to be a blown head gasket. Does anyone know of a site for a service manual...specifically, head bolt torque and valve clearance? Thanks!

A blown head gasket is fairly common occurrence on these engines, but I want to make sure that you've checked the oil level to be sure it's not overfilled, and also to be sure the oil is not thin and doesn't smell like gas. If not, proceed with head gasket replacement.

I can't recall torque values, but I can get them for you. I'd set both valves to .005".

thanks for the reply cheese...I had already changed the oil and started to check it out but once it got hot would start billowing white smoke. Tore it down and found the h/gasket blown as suspected, thanks in a large part to these threads. I was told 220 in. lbs. for the head bolt torque...don't have the torque sequence but thought I'd start at the bolts near the dowels first and work crosswise, torqueing in small increments until final torque....sound ok to you? I hate spending $30+ for a service manual but also couldn't find a manual (free) on-line.

Cylinder head torque is indeed 220 inch pounds. I recommend starting with the center most bolts and working your way outward, back and forth from center. Begin at 120 then step up to 180 and then finally 220 pounds, twice around at the final 220. Cheese mentioned a possibility of fuel in the crankcase because you mentioned a whiteish smoke. Usually, white smoke indicates fuel in the oil which would be as a result of a faulty inlet needle and seat and/or a faulty float in the carburetor. Just don't want you to overlook this possibility.

The first thing I would look at is the carb. make sure all settings true.. Be sure gas is fresh. Check engine compression, remove plug, hold thumb over hole, and crank over, pressure should move your thumb off of hole. Be sure spark is good. Be sure air filter is clean. Spark Plug, new, and gap.....Do you have engine noise ?? If all of the above check out, is probably, a broke ring, piston, or cylinder bore.. Good Luck...........

After you get the head back on, watch the carb air inlet with the air filter removed. If you are getting a lot of crankcase blow back from the breather inlet into the carb air inlet, you may be looking at an over haul. We have been experiencing numerous cases of these engines coming in with the smoking condition which gets progressively worse with time. We honed the cylinders and put in new rings. Also Briggs is changing where the engine crankcase breather is located when a new short block in installed.

Google Briggs and Stratton motors and you can find the owners manual. I think they run around eight bucks.

By the way, there is an excellent trouble shooting section that's really worth checking out.

I hope this helps.

Thanks for all the replies and helpful advise....it appears the h/gasket is the only problem at this point. Cylinder walls are in great shape and I can feel ring resistance when trying to move the piston in the bore...maybe I lucked out since this engine has always run synthetic oil since new. The cooling fins are clean and there are no signs of excessive heat. I'm hoping to put it back together one night this week and I'll let you know.

Cylinder walls are in great shape and I can feel ring resistance when trying to move the piston in the bore...maybe I lucked out since this engine has always run synthetic oil since new.

Hopefully you allowed some break in period before changing to synthetic. Something to keep in mind should the head gasket not solve it.

It's got about 400 hours on it and has never used any oil....the engine failed all at once...blew a few puffs of smoke, cleared, and then while going down a hill started really smoking...I'm thinking the valve cover and pushrod channel filled because of the angle and then the compression due to the blown gasket was blowing it into the carb via the breather. It was running before I tore it down but it couldn't handle going downhill without smoking. There is a burned spot on the gasket where it meets the crankcase....block and head look good after cleaning.

Just wanted to let you know the head gasket solved the problem...running great! Now if the snow would only melt enough to let me get out there and play!!

Great! Glad you got it, and thanks for the update!