It might just be that I need to give the venturi a good rinse/cleaning, but I am not sure if there should be some year end maintenance for a diesel engine interior. Not wanting to remove the piston and crankshaft, but is it important to remove the backplate and rinse out the interior from time to time? If so, what should be used - fresh fuel, acetone, straight kerosene? Thanks,

After run oils and flushing are recommended for glow engines because of the hydroscopic (absorbs water) and corrosive nature of the methanol in glow fuel causing rust and corrosion in glow engines (especially the ball bearings). However, a diesel engine is not nearly as susceptible to rust because diesel fuel is not hydroscopic like glow fuel is. Diesel engines do suffer the same complaints as glow engines concerning congealed castor oil if left to dry out over long periods. If you intend to store a diesel engine for many months or years, then I suggest flushing the crankcase with Kerosene to remove the castor oil. Then lubricate the engine crankcase and cylinder with a squirt or two of automatic transmission fluid (ATF) and flip the prop several times to evenly distribute the ATF throughout the engine. ATF does not congeal like castor oil does. If you are only storing it over the winter until the spring flying season arrives, then I would not bother to flush out the engine. Just give it a squirt of ATF and put it away. Diesel engines normally run cooler than glow engines and don't build up baked on castor oil varnish deposits as much as glow engines do. However, diesels can still get carbon buildups that may require the occasional cleaning.