I have a 69 3 cylinder 4000 diesel. Tractor runs excellent uses no oil very minor blow by from tube if any. The tractor seems to loose prime over night, but if I leave the fuel shut off pulled out it fires right up. if I push it in over night its a pain to get cranked. could my metering valve be worn? tractor has zero leaks! Also if it does loose prime I have to crank it over kill the fuel while cranking till I see no smoke gently push in on the shut off. do this three or fours times and theres a sweet spot for it to catch and crank. can't go to far forward or back buy once runing you can push all the way forward.