I have a 16 hp Briggs & Stratton opposed cylinder, 1980 vintage which just started blowing oil out one of the 2 breather pipes into the air filter and saturating it with oil. I searched the forum and saw that this has come up a couple of times before with different engines and once with another 16 hp Briggs & Stratton engine of the same vintage. The answer was to replace the Breather assembly, but at least in that case... it didn't solve the problem. Before I invest in one, or possibly both breather assemblies at the cost of $26 to $30 each, any other suggestions to confirm that it's the Breather assembly which isn't working? It takes about a minute before the oil start sputtering out - which I also saw happened with another case. I take the dip stick out out and get positive pressure coming out of the tube. Is that normal?

I'm leaving town early tomorrow morning so won't be able to check back for about 5 or 6 days, but thanks in advance for the help.

DO NOT replace breather, the oil level is high due to fuel leaking into crankcase from carburetor. VERY common problem. Drain oil and put in fresh to proper level run machine again and see if problem goes away.

Don

Actually, the oil level is at the bottom of the "acceptable" area on the dipstick, when the dipstick has been screwed all the way back down to it's seated position and then removed to check the level (not normally the way a screw in dipstick is read I think). If I clean the dipstick and then insert in back into the tube without screwing the top down and then withdraw it... it actually reads below the acceptable area (hash marks) on the dip stick. I don't think that the crankcase is too full with an oil/gas mixture. Any other thoughts or should I gamble $40 and replace the breather assembly on that cylinder side. Also the other breather tube seems find and doesn't spit oil out.

I just ran it again and it took 2 or 3 minutes before the oil spitting started, but sure enough, it hasn't fixed itself in the past week and is doing it even at the lower oil level in the crankcase.

Thanks in advance for any help or advice.

As a follow-up to this post, I thought I should let people know what outcome I had, to help anyone else who may encounter the same problem. Let me see, if I remember the sequence right, it went something like this:

#1. I ordered and replaced the breather assembly. It's not a real expensive part and it is pretty easy to replace. This suggestion came from the answer to another post by someone else with the same problem.

#2. I still had oil coming up into the air cleaner and being sucked into the carb, creating a smoky condition like a broken piston ring (Not to be confused with the oil that was running down onto the muffler, also creating a smoky condition). How disappointing.

#3. I figured I would try some extra heavy weight oil, to get through the summer until this winter when I'd have more time and maybe the inclination to tear the engine down and replace the rings. I'd suspected that a ring had broken, causing excessive crankcase pressure (blow-by into the crankcase) and oil-smoke exhaust & excess oil consumption. When it ran, it looked like a mosquito fogger.

#4. Somehow, I noticed that when I ran the engine without the air cleaner on, it didn't smoke or blow oil up out the new breather pipe (later to get sucked into the carb or run down onto the muffler). I guess I had the air cleaner off to monitor the breather tube outlet. Finally the light went off... don't try running the engine with the old air cleaner, even though it was practically new. It (the air cleaner) had gotten oil soaked the first time the engine ever had the problem. I'd cleaned the oil off and wiped it up, but the paper still had a coating of oil in it, preventing the engine from "breathing" right. Since the ends of the breather tubes come out in the inside of the air cleaner, when the air cleaner is plugged, the tubes are under really low manifold pressure (caused from the air being sucked out through the carburetor inlet). This must make even the brand new breather assembly not work (after all, the breather assembly is nothing more than an oil separator, allowing crankcase vapor to pass through it but straining out oil droplets). When you have crankcase pressure pushing the oil on one end and manifold vacuum sucking the oil/vapor mixture on the other end of the tube... it's just too much for the separator to work.

#5. I ordered and replaced the air filter and everything seems to be working well again. Mowed the lawn once so far and no smoky exhaust, no oil all over the engine and no oil running back into the carburetor. The new breather seems to be working just fine.

Hope this might help the next person with this problem. If you have the problem, I'd look at both answers I received and check the oil for gas in it (change it if you suspect gas diluting it) and then next try changing the breather assembly but above all... make sure you have a clean air filter when you try the engine after your repairs.

Thanks to all who answered my and other posts of this problem. These user boards are wonderful for solving problems. Thanks again.

I had a similar problem. Battery was almost dead and wouldn't start tractor. Tried to start it about 5 times and failed. Finally jumped it with my truck and it started but began blowing oil out the breather almost immediately. Checked the oil and clearly it had gas in it. I drained the oil and replaced it with new 30W. Took the carb off, removed the breather, drained them both and cleaned them. Reassembled everything and put the battery on a charger overnight. Next day with everything dry and new gas it fired up and ran like a charm. Hope this helps someone.