My teenage son bought himself a D105 tractor several years ago. After the winter, he pushed it onto our driveway, and we completed an oil change and lube. Afterwards, he started up the tractor, drove it for about 15 feet, and a loud boom followed and the tractor stopped. After about 3 weeks of sitting in our garage not knowing what to do, it was picked up by an authorized dealer for the Home Depot extended warranty he took out on the tractor. It sat another 2+ weeks before the dealer could look at it, and said it was low on oil, and that's what caused the engine to blow. Of course, the insurance plan will not cover it now since they stated it was low on oil, when in fact it was filled with a full tank of oil before the engine blew. Can anyone please give this lost mom some advice on what could have been the cause of the engine to blow after an oil change/full tank of oil? Thank you soooo much!!
You know there's low oil, and then there's low oil.
I gotta tell you a story, its how I got started in automotive stuff. So I was living in Germany as an American G.I. I got interested in cars as a hobby. A friend of mine had crashed his car into a curb at high speed, and the insurance company called it a total loss. He wanted $300 for it. I wanted the engine for a possible project. Well it turns out the insurance estimator goofed and it wasn't a bent frame / broken transmission. I was able to fix the car for the price of one new wheel, and $25 in parts and some work. I sold the car for $1800 to somebody else in my unit. The next day I see the guy on the side of the road with the car. I told the guy to let me look at it and if it wasn't easily and immediately fixable, I'd give him a full refund of his money.
So it turned out the car I bought for its engine had spun the bearings for one of the connecting rods right out. When I dissembled the engine that was quite clear. It was equally clear that failure had absolutely nothing to do with the curb accident. I bought the car for the engine, and thought I was selling a car with a sound engine. My point here, is that things wear (when maintained poorly) and we have little control when they finally let go. I ended up rebuilding the engine from the bottom up and selling the car again for $1800. I took this hobby to the max, for when I left the Army I went to work for an automotive company as a design engineer. Way fun.
So back to your tractor.. what makes an engine have excessive wear... is low oil. The bearings need lubrication and from year #1 to the period before you changed the oil you may have been low (and / or using really dirty oil...) Bearings wear. And when they wear out bad things happen. (You did say the tractor was purchased several years before. I'm guessing that it had in fact been run before, right?) The fact that it was full of clean oil when it finally let go won't hide the fact that the bearings, crankshaft, connecting rods and camshaft need oil. I'm guessing those parts were heavily scored, a sure sign of low (and/ or heavily) contaminated oil.
Have you asked the dealer to see the parts in question?
Its also possible the new oil caused a problem (perhaps a grossly wrong grade?) but I really doubt that. Stuff happens. Just never at the right time, sigh.