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Briggs-Fan
Briggs-Fan, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1223
Experience:  over 15 years experience in small engine repair, multiple certifications
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Lawn Tractor Toro LX 426 Model 13AL60RG544 with Briggs and

Customer Question

Lawn Tractor Toro LX 426 Model 13AL60RG544 with Briggs and Stratton 20 HP 540cc engine
Started burning oil and blowing blue smoke immediately after backfiring. Backfire was caused by putting in reverse prior to disengaging the cutting blade causing it to shutdown. On startup it backfired and started blowing blue smoke.
Have tried changing oil, emptying and refilling gas tank and changing spark plug. Now it take about 10 minutes cutting before it starts blowing blue smoke. Plug is wet when I check it after running for 1/2 hour
Submitted: 7 months ago.
Category: Small Engine
Expert:  Briggs-Fan replied 7 months ago.
Hi my name is ***** ***** welcome to Just Answer. Can you check the oil to see if it is thin or smells like gas
Customer: replied 7 months ago.
I cannot tell if the oil is thin or smells gas... I don't think so
Customer: replied 7 months ago.
It takes 10 minutes for it to start blowing blue smoke after starting which leads me to believe there isn't oil in the gas
Customer: replied 7 months ago.
Do you have anything else in the way of an answer for me?
Expert:  Briggs-Fan replied 7 months ago.

My concern is the plug fouls, and it's smoking. Does it backfire while running some ?

Expert:  Briggs-Fan replied 7 months ago.

After changing the oil was it better at first

Customer: replied 7 months ago.
It doesn't backfire while driving at all. It even seems to run fine, and starts fine. It has only backfired on the one occasion before this smoking started. When I changed the oil it seemed to run fine at first, but 10 minutes into cutting it started smoking. This is what it does now.... starts smoking 10 minutes into it.
Customer: replied 7 months ago.
Also, when it starts to smoke, it smokes a lot, not just a little.
Expert:  Briggs-Fan replied 7 months ago.

If the oil doesn't smell like gas or is thin then it could be the rings or valves , being it's taking 10 minutest to smoke makes sense because the rings and valves are metal and metal expands when hot so if the rings get hot expand and lose their seal oil will bypass them into the valves and burn . It could also be a blown head gasket , does it leave oil around the engine at all ?

Expert:  Briggs-Fan replied 7 months ago.

If its a ton of smoke you most likely have a blown head gasket , like does it smoke the yard up ?

Customer: replied 7 months ago.
it smokes the yard up. But I don't see any leaking oil or signs of leaking oil. And would the plug be wet (running too rich) if the head casket was blown. Could it be an inoperative crankcase breather? Another puzzling thing is that as soon as it backfired, it started blowing blue smoke immediately.
Expert:  Briggs-Fan replied 7 months ago.
the plug would foul , I'd pull the head and replace the gasket . It does sold like a head gasket issue
Expert:  Briggs-Fan replied 7 months ago.
Check the air filter , is it oil stained ?
Expert:  Briggs-Fan replied 7 months ago.
If you can get a leak down tester we can test it to verify
Customer: replied 7 months ago.
Air filter is clean. I replaced it last year when this all started. I haven't run the tractor much since then because of the issue (maybe 2 hours in total). But it is not soiled at all. Compression and ignition were both checked by a technician at that time and were ok. Is a compression test the same as a leak down test? Also he checked and tightened breather plate and wrote that there was a possible leak. The tractor seems to be fine at idle and only starts smoking at full throttle with the blade engaged cutting.
Expert:  Briggs-Fan replied 7 months ago.

A leak down test would show if the head gasket is leaking

Customer: replied 7 months ago.
Could it not be a inoperative crankcase breather? Doesn't a compression test tell you that it isn't a head gasket?
Expert:  Briggs-Fan replied 7 months ago.
Not always , a leak down test would show if the head gasket is leaking
Customer: replied 7 months ago.
Also the smoke is blue not white? Again, could it be an inoperative crankcase breather?
Expert:  Briggs-Fan replied 7 months ago.

If the crankcase breather is blocked it will push oil out the dip stick hole

Expert:  Briggs-Fan replied 7 months ago.

Look at this video of how this rider is smoking. It has a blown head gasket

Expert:  Briggs-Fan replied 7 months ago.

https://youtu.be/bc0gfCdsw6Y

Customer: replied 7 months ago.
Mine doesn't smoke nearly this bad (maybe only 1/20 th of this and it is blue smoke and not white smoke. Also I have no visible signs of oil on the engine like they do. In addition it doesn't smoke right away.
Customer: replied 7 months ago.
Is there anything else it could be? Briggs and Stratton website lists inoperative crankcase breather as one of the possibilities, so that is why I asked.
Expert:  Briggs-Fan replied 7 months ago.
Then most likely it's a ring or valve issue , your not leaking oil anywhere , the oil doesn't smell like gas or is thin. The smoke is blue which is oil burning .