OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines smokey briggs and stratton

i've acquired a briggs and stratton sprint 375 .it had no oil to speak off .I've since given it new .not over full .on opening the breather there appears to be far to much oil .ive cleaned it up and restarted the mower but it still smokes and breather box again is covered with oil any ideas would be welcome thanks

G'day,
Hi and welcome Baldrick. When you say the engine was run with no oil, do you know what length of time it was ran for? How much oil did you put in when you re filled it as the correct amount of oil for a small Briggs and Stratton is 600mls. If you ran the mower then took the breather off within a short period of time then there may be a considerable amount of oil sitting in there because there has not been enough time for the oil to drain fully. If the mower were drastically over full then oil would continue to run from the oil delivery port until it emptied past the bottom of the hole.
Anyway there is a good chance that the smoke is caused by worn engine parts if it was ran for an extended period of time with no oil. Sometime an indication of this is when the oil turns black very quickly - within 5 minutes or so of running.
Regards jay

When the aluminium-bore engines run out of oil the piston rings are likely to score the bore when they seize. Often you can easily get them going again just by putting in oil and working them gently until they rotate freely, but the acid test is when you start them and watch for smoke. A small cold-start puff of just tenths of a second duration is probably tolerable - for one thing it may get even better as the piston rings gradually smooth out the localised bore damage. However if it ran for a long, long time with just about no oil there will probably be major longitudinal scores in that aluminium bore. That is likely to produce continuous smoke, not a cold-start puff. I personally don't know of a cure for that other than taking off the head, inspecting the bore for scoring, and either reboring or replacing the cylinder if scoring is present. If it is just worn rings without bore-scoring, you can fit a new set of rings pretty cheaply.

grumpy,

Another thing that happens with the motors and is common is that the piston ring gap lines up which allows the oil to go straight into the cylinder head area.

I would do what you say to check for scoring but if no scoring the next step would be to check to see if the ring gap has lined up.

gadday mates and thanks for the quick replies. i've know idea how long the motor was run on low oil .i refilled with 30 grade oil 600 mls. i cleaned the oil from the valve gallery and the mower has sat for a day since. i have started it again and it smokes up straight away lots of oil in the gallery and the plug looks oily the engine seems to run fine .does the oil come from around the valves stems [tappets end ]or is there an oilway . i guess i will strip the head and barrel and have a look see . i thought there may have been an easy fix as pulling the cord it felt like there is compression.thanks again for the response Pete

Unless there is something drastically wrong with the breather system, I think you'll find the oil is getting past the piston rings. Someone with more experience with the B&S breather should be able to help clarify the first possibility. If it isn't that, I think the next step is to remove the cylinder head and inspect the bore.
I believe it is quite common for continuous oil smoke to appear due to poor ring sealing, while a B&S still has enough compression to start and run pretty well. Old cars certainly can do that - the city used to be full of old smokers in the days when cars used to be run into the ground. In the 1950s and 60s, sometimes it was as thick as fog if you got behind a real stinker. Thank heaven for chromed steel-rail rings.