1*The mechanics that worked on your briggs were not good small engine mechanics, or they would have identified the problem and corrected it.
2*The only other possibility is that something you were doing was causing the engine problems. i.e. bad gas, water in gas, low oil, etc..
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1*Some design flaws and lemons can't be corrected I believe my MTD falls under this.
2*When you take in to the shop and they clean the fuel system and fill the tank with new fresh gas and you bring it back unload it and mow for an hour or so and it goes right back to doing the same thing how could it be a bad gas or a water in gas issue?
I did not do any maintenance of a poorer quality on the MTD than I do on any of my other equipment and they never give me such problems as the MTD does.
As far as the low oil issue you can't run it low as it keeps increasing the level on the dipstick.
The tractor has always bellowed blue smoke from the exhaust when first starting.
It has done this from the day I got it and first started it.
skinderflirt