I clean my '85 300SD engine by blasting it with a cleaner and then pressure washing the hell out ot EVERYTHING. The motor never even misses a beat when I do this. By using this cleaning method is how I found out my intake was leaking.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R