PISTON FITTING Jeep Grand Cherokee WK2

PISTON FITTING

The pistons are "select fit" to achieve proper oil clearance. Engine block cylinder bore diameter grade markings (1) are stamped into the left side of the engine block. These marks are read from left to right, corresponding with cylinder number 1, 2, 3, 4, 5, 6.

Engine block cylinder bore diameter grade markings correspond to specific cylinder bore diameters. The chart below identifies the two engine block grade markings and their associated cylinder bore diameters.

Scheme 223

The piston is marked with the piston size (1 and 2) on the piston crown. The pistons are available in two different sizes in order to achieve the desired oil clearance. Select the piston size that corresponds to the engine block cylinder bore diameter grade markings for each cylinder.

Pistons are available in two sizes. The chart below identifies the two piston sizes.

Scheme 224

Note. Typical coated piston shown in illustration.

The coated pistons are serviced with the piston pin and connecting rod pre-assembled. The coating material (1 and 2) is applied to the piston after the final piston machining process. Piston installation into the cylinder bore requires slightly more pressure than that required for non-coated pistons. The bonded coating on the piston will give the appearance of a line-to-line fit with the cylinder bore.

Scheme 225

1. Mount Dial Indicator Set (special tool #C-3339A, Set, Dial Indicator) to a stationary point on the engine. Locate the probe perpendicular to and resting against the connecting rod cap being checked.
2. Move the connecting rod all the way to the rear of its travel.
3. Zero the dial indicator.
4. Move the connecting rod forward to the limit of travel and read the dial indicator. Compare the measured side clearance to the specification. Refer to «Engine - Specifications»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#36l-engine-service-information__specifications) .
5. Repeat this procedure for each connecting rod. Rotate the crankshaft for connecting rod accessibility.

Scheme 226

1. Slide a snug-fitting feeler gauge between the connecting rod and crankshaft journal flange. Compare the measured side clearance to the specification. Refer to «Engine - Specifications»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#36l-engine-service-information__specifications) .
2. Repeat this procedure for each connecting rod. Rotate the crankshaft for connecting rod accessibility.

1. Disconnect and isolate the negative battery cable.
2. Remove the oil pans, engine timing cover and cylinder heads. Refer to «CYLINDER HEAD, REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#36l-engine-service-information) .
3. Remove the engine oil pump. Refer to «PUMP, ENGINE OIL, REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#36l-engine-service-information) .
4. Remove the eight main bearing cap bolts from the windage tray in the sequence shown in illustration and remove the windage tray (1).
5. If necessary, remove the top ridge of the cylinder bores with a reliable ridge reamer before removing the pistons from the engine block. Be sure to keep the tops of pistons covered during this operation. Pistons and connecting rods must be removed from the top of the engine block. When removing piston and connecting rod assemblies from the engine, rotate the crankshaft CW so that each connecting rod is centered in the cylinder bore. CAUTION: DO NOT use a number stamp or a punch to mark connecting rods or caps, as damage to connecting rods could occur NOTE: Connecting rods and bearing caps are not interchangeable and should be marked before removing to ensure correct reassembly.
6. Mark connecting rod and bearing cap positions (1) using a permanent ink marker or scribe tool. NOTE: Typical V6 engine configuration shown in illustration. CAUTION: Care must be taken not to damage the fractured rod and cap joint face surfaces, as engine damage may occur.
7. Remove the connecting rod cap bolts (5) and the connecting rod cap (4). Discard the cap bolts. CAUTION: Care must be taken not to nick crankshaft journals, as engine damage may occur.
8. Remove the plastic guide plates (3) from the Guide Pins (special tool #8189, Guide Pins) (7) and install the Guide Pins to the connecting rod being removed. CAUTION: Avoid contact with the piston oil cooler jet(s). Positioning of the oil cooler jet(s) is critical for proper engine operation.
9. Remove the piston and connecting rod (1) from cylinder bore.
10. Repeat the previous steps for each piston being removed.
11. Immediately after piston and connecting rod removal, reinstall the bearing cap (4) on the mating connecting rod to prevent damage to the fractured cap and rod surfaces.
12. If required, remove the piston rings. Refer to «RING(S), PISTON, REMOVAL»(/jeep/grand-cherokee/wk2-2010-2013/remont/mechanical/#36l-engine-service-information) .
13. Repeat the previous steps for each piston being removed.

1. Using a suitable cleaning solvent clean the pistons in warm water and towel dry.
2. Use a wood or plastic scraper to clean the ring land grooves.