First, welcome to OCC......
The 1811 was one of the best series of tractors CCC/MTD built. Like with anything, the amount of care and maintenance is important.
The one of issues that we see frequently, is the amount dirt, debris, crud, grease, oil, grass clippings sucked up into the Fan intake and building up around the Flywheel. Unfortunately, the only inspection that can be done, is to remove the engine from the tractor and remove the shrouds for inspection and cleaning.
Blowing compressed air into that area (while still in the tractor) is better than nothing, but won't get into every area.
Other than that, the normal maintenance should be done.
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Roland Bedell
CC Models: 100, 105, 1450, 782, (2) 784, & 2072
Buy: Made in the USA 