Cummins ISX11.9 CM2250 – Service Manual 017-002   Cup Plug

This repair method pertains to components that have leakage at a cup plug, due to incorrect fit of the cup plug in the cup plug bore.

All cup plugs must be replaced if the component is cleaned in a “hot tank”, spray washer, or similar equipment. This cleaning activity can interrupt the sealing capacity of the sealant.

Use a center punch to mark the cup plugs for drilling.

CAUTION  Do not allow metal shavings to fall inside the engine when drilling a hole in the cup plug. Damage to engine components can occur.

Drill a 1/8-inch hole in the cup plug.

Use a dent puller to remove the plug.

Discard all used cup plugs. Do not use them again.

CAUTION  Do not allow metal shavings to fall inside the engine when drilling a hole in the cup plug. Damage to engine components can occur.

Cup plugs can be removed by using a center punch to mark the cup plug for drilling.

Drill a 3 mm [1/8-inch] hole in the cup plug.

Use a dent puller to remove the plug.

Lightly scrape the bore to remove any corrosion or carbon buildup.

Wipe the bore with a cloth saturated with a spray cleaner.

Measure the bore diameter in the vertical direction and in the horizontal direction.

Both axis measurements must be within 0.02 mm [0.001 inch] of each other.

Compare the bore diameter with the recommended bore size of the cup plug being used. Use the table at the end of this procedure for specifications.

NOTE: If the correct cup plug is being used, but the bore is incorrectly sized, the bore must be repaired. The recommended repair method is to enlarge the bore for the next larger cup plug size. A listing of available cup plugs and their dimensions is provided at the end of this procedure.

Enlargement of the cup plug bores can be accomplished by reaming or boring the faulty bore. Use the existing bore for location reference when enlarging the bore.

The surface finish of the enlarged cup plug bore is very important in making a successful repair. The surface finish of the bore must be a minimum of 2.03 µM [80 µ inch]. A surface finish comparator can be used.

NOTE: Units of measurement are: Micro-meter [Micro-inch].

CAUTION  Excessive sealant can run back into the engine and cause damage to other components. Allow the sealant to dry for a minimum of two hours before operating the engine.

Apply a 2 mm [1/16 in] bead of cup plug lock ‘n seal, Part Number 3375068 or equivalent, to the outside diameter of the cup plug and the inside diameter of the cup plug installation bore.

A cup plug driver must be used to install the cup plug to the correct depth in the cup plug bore.Use the following cup plug drivers:

• Part Number 3822372 – 9.7 mm [0.38 in] cup plug.
• Part Number 3376816 – 25.4 mm [1.00 in] cup plug.
• Part Number 3376058 – 60.5 mm [2.38 in] cup plug.

Use cup plug driver handle, Part Number 3376795, with cup plug driver, Part Number 3376816.

The cup plug must be installed with the edge of the plug 0.5 to 1.0 mm [0.020 to 0.040 in] deeper than the entrance chamber of the bore.

Do not install the plug too deep. The cross drillings in the cylinder block can be blocked shut. If the plug is not installed straight and flat, it must be replaced with a new cup plug.

CAUTION  Excessive sealant application can run back into the engine and cause damage to other components. Allow the sealant to dry for a minimum of two hours before operating the engine.

Apply a 2 mm [1/16 in] bead of cup plug lock’n seal, Part Number 3375068 or equivalent, to the outside diameter of the cup plug and the inside diameter of the cup plug installation bore.

Install the replacement cup plug.

Use a suitable cup plug driver or mandrel to correctly position the cup plug.

Check to make sure the cup plug is correctly installed. The top of the cup plug must be 0.0 to 2.29 mm [0.00 to 0.090 inch] below the entrance chamfer.