there is no vendor that sells engines made in india that are devoid of sand, unless you find an assembler that will take the time to properly
clean the castings... and even then there will be those that slip through.
the issue with the sand for the most part is the insanely ignorant original design of the big end oiling system that has carried over in the listeroids
coupled with pistons that trap sand under the insides, is a recipe for disaster.
any engine that does away with the top end oiling has moved to proper engineering practice, beit with crossdrilled crank or with hollow dippers.
sure the big end original oiling system works, but you got to have QC to assure that there is a clean piston etc.
having done the math, and provided the equations, done the research, and been a diesel engine mechanic for now just over 33 years
i defy anyone to defend the original lister big end oiling design, it is marginal at best, adequate if everything is clean and perfect
also because it has been said the original cost as much as a house,, for godsakes the clones are but a fraction of the original price for a lister
using even 1950 pricing.
you get what you pay for, and then put whatever labor/dollar you like to get it to the level of quality that is sufficient for your personal needs.
no other engine on the market today allows one to do that.
bob g