Usage:
All 3208 Truck Engines With 1W5793 And 1W5799 Basic Piston Groups
Reference: Engine News, August 13, 1980, Page 6. The article " Carbon Cutting On Thrust Side Of Piston" is about the same subject as this article, but it is for 3300 Series Engines.
Pistons with offset (not in the center) pin bores are now used in the above 3208 Engines.
Because of the offset pin bore design, the piston will have carbon cutting on the side of the piston top land closest to the piston crater. See the illustration. The area of carbon cutting will be approximately 25.4 mm (1.00 ") wide but will not extend all the way to the top piston ring groove.
This carbon cutting, which comes during the first 100 hours of operation, is a normal condition for pistons with an offset pin bore, and it will not have an effect on performance of the engine. Use the illustration as a "use again" guide. Carbon cutting will be shown in a future revision of the "Guideline For Reusable Parts - Pistons and Cylinder Liners, " Form No. SEBF8001-01.
The offset pin bore design decreases vibration of the cylinder bore caused by piston slap (side to side movement) when the piston moves through the top center position. The offset pin bore permits the piston to move more smoothly through top center. Vibration of the cylinder bore walls can cause cavitation erosion. The result is pitting between the cylinders on the water side of the cylinder walls.
High frequency vibrations can some times cause pitting of the outside of the cylinder bore wall when there is no corrosion.
For this reason, regular cooling system maintenance is necessary. The coolant must prevent rust, corrosion and pitting.
Water is not a good coolant because water, without cooling system conditioner, becomes an acid solution very rapidly. See the August 18, 1981, Truck Engine News article, "Cooling Conditioner Elements And Their Capacities," for the correct amount of cooling system conditioner and the service interval.
NOTE: Do not add cooling system conditioner to Dowtherm 209 or Dowtherm 209 Full-Fill.