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While mowing the lawn yesterday the engine backfired and blue smoke emerged from the exhaust. I opened the hood and the plastic cover on the flywheel had blown off taking the dipstick tube with it. After reattaching the dipstick tube I started the engine which ran smoothly with the exception of the continuous blue exhaust. What's the likely problem? What's the likely fix? Will it damage the engine to continue to run the machine? Thanks for the advice.
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Do you have a Tecumseh, Briggs or Kohler engine? What size is the engine and what is the model number?
Let me know.
Eric
The engine is a Briggs 15.5 HP OHV model 28N707
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How old is the mower? This is a very odd problem. Is the oil level correct? Is the engine knocking or burning oil?
Have you checked any other message boards for a similar problem?
Do you have a compression gauge to check the engine compression?
Let me know.
Eric
The mower is 11 years old. The oil level is correct and the engine was not (before the incident) and is not now knocking, but it is now burning oil. I don't have a compression gauge.
Here's what I think happened: As I was mowing the yard the flush rotating screen (plastic piece on top of the flywheel) lost three of its screws and spun off. Still being held by a fourth screw, the screen jammed the engine for an instant until the fourth screw bent and broke, releasing the plastic screen which tore the oil dipstick tube from its position. The engine backfired once or twice and began spewing blue smoke from the exhaust. I immediately shut it off and discovered what had happened. After remounting the dipstick tube I checked the oil level which was just a bit down from the correct level. I briefly started the engine and it sounded fine...no knocking...and seemed to run smoothly, but still spewing lots of blue exhaust. I shut it down after about 10 seconds and that's where we are. Hope you can gain some insight from this and give me advice. Thanks again.
AnswerYears ago, about that time, Briggs had some issues with crankcase vacuum. One problem was the oil dipstick tube o-ring. Anyhow, if the engine looses vacuum it will burn oil due to oil getting past the piston rings.
This may have happened to your engine. If some oil got past the rings then it probably got pushed into the muffler which causes engine to smoke (blueish/white).
You can remove the muffler and soak it in some carb cleaner to help get rid of oil or you can just run the mower...it will smoke for a while.
I would go ahead and use the mower but keep and eye on engine oil comsumption. If you notice the engine using oil then you may have to perform a leak down test.
Does this help?
Eric
