they do not smoke at all. There is some blow by when the oil filler cap is removed while running. The service was perfect on these. I honestly think these are the original units, as there is no sign of wrench marks and the decals on the engines are as worn as the rest of the chassis. One has had the head off I think. These would have had to have been run almost constantly, with most of the use as a warm spot to get out of the cold, that provided lights for work in the rail yard. These have been run into things a lot as each panel of the essex cab is a different color and show signs of contact.
My boat mechanic says these engines will last a long time IF the valves are kept in adjustment, And they are used a lot.
rick