CRANKSHAFT Dodge Nitro I

CRANKSHAFT

The crankshaft is constructed of a forged micro alloy steel. A six throw, nine counterweight crankshaft is supported by four select fit main bearings with number two serving as the thrust washer location. The six separate connecting rod throws are an even-firing design which reduces torque fluctuations while a torsional vibration damper is used to control torsion caused vibration of the crankshaft. Rubber lipped seals are used at front and rear. The front seal is retained in the oil pump case and the rear seal is retained in a block-mounted housing.

The crankshaft transfers force generated by combustion within the cylinder to the flywheel or flexplate.

Scheme 296

Scheme 297

1. Remove engine from vehicle. See «REMOVAL»(ref-306143-S20513227792008120900000).
2. Remove oil pan. See «REMOVAL»(ref-306143-S12798993982008120900000).
3. Remove oil pickup tube.
4. Remove front timing belt cover. See «REMOVAL»(ref-306143-S37847068952008120900000).
5. Remove timing belt and tensioner. See «REMOVAL»(ref-306143-S05505308212008120900000).
6. Remove crankshaft sprocket. See «REMOVAL»(ref-306143-S05505308212008120900000).
7. Tap dowel pin out of crankshaft.
8. Remove oil pump assembly. See «REMOVAL»(ref-306143-S12967298572008120900000).
9. Remove crankshaft rear oil seal retainer (Refer to «REMOVAL»(ref-306143-S00280118942008120900000) ). CAUTION: Connecting rod bearing caps are not interchangeable and should be paint marked or scribed before removal to insure correct assembly. DO NOT use a metal stamp to mark the bearing caps.
10. Remove connecting rod bearing caps. (Scheme 296) WARNING: Main bearing caps are not interchangeable and should be paint marked or scribed before removal to insure correct assembly. DO NOT use a metal stamp to mark the bearing caps.
11. Remove main bearing caps (1). Main bearing caps (1) are not interchangeable and are marked to insure correct assembly. (Scheme 297)and see scheme 257. 1 - MAIN CAPS 2 - BOLTS 3 - MAIN BEARING-LOWER 4 - CRANKSHAFT 5 - THRUST WASHERS 6 - MAIN BEARING-UPPER 7 - ENGINE BLOCK
12. Remove crankshaft (4) from cylinder block (7). see scheme 257

Note. Before installing crankshaft, refer to CRANKSHAFT MAIN BEARING FITTING and BEARING - CONNECTING ROD . See STANDARD PROCEDURE for crankshaft main bearing. See STANDARD PROCEDURE for connecting rod bearing.

The crankshaft journals should be checked for excessive wear, taper and scoring. Limits of taper on any crankshaft journals should be held to 0.010 mm (0.0004 in.). Limits for journal roundness should be 0.008 mm (0.0003 in.). Journal grinding should not exceed 0.254 mm (0.010 in.) under the standard journal diameter. DO NOT grind thrust faces of Number 2 main bearing. DO NOT nick crank pin or bearing fillets. After grinding, remove rough edges from crankshaft oil holes and clean out all passages. Crank journals must be polished smooth 0.10 micron ra.

Scheme 298

Scheme 299

1. Install crankshaft upper main bearings in cylinder block. Ensure oil holes in bearings line up with oil holes in cylinder block. (Scheme 298)and «STANDARD PROCEDURE»(ref-306143-S22315068822008120900000). 1 - MAIN CAPS 2 - BOLTS 3 - MAIN BEARING-LOWER 4 - CRANKSHAFT 5 - THRUST WASHERS 6 - MAIN BEARING-UPPER 7 - ENGINE BLOCK NOTE: Care must be taken not to damage the journals or bearings during crankshaft installation.
2. Install the crankshaft (4) to cylinder block (7). see scheme 259 1 - FRONT THRUST WASHER
3. Move crankshaft forward to limit of travel. Lubricate and install the front thrust washer (1) by rolling the washer (1) onto the machined shelf between the No. 2 upper main bulk head and crankshaft thrust surface. (Scheme 299)
4. Move crankshaft rearward to limit of travel. Lubricate and install the rear thrust washer by rolling the washer onto the machined shelf between the No. 2 upper main bulk head and crankshaft thrust surface. (Scheme 299) 1 - MAIN CAPS 2 - BOLTS 3 - MAIN BEARING-LOWER 4 - CRANKSHAFT 5 - THRUST WASHERS 6 - MAIN BEARING-UPPER 7 - ENGINE BLOCK
5. Install lower main bearings (3) into main bearing caps (1). see scheme 261
6. Lubricate lower main bearings (3) with clean engine oil. NOTE: Lubricate main bearing cap bolts (2) with engine oil before installation.
7. Install each main cap (1) and tighten bolts finger tight. The main bearing cap bolts (2) must be tightened in the proper sequence. First the inner main cap bolts (2), secondly the windage tray bolts, lastly the main cap tie (horizontal) bolts (6).
8. Install the inside main bearing cap bolts (2) and tighten to 20 N.m + 1/4 turn (15 ft. lbs. + 1/4 turn).
9. Measure crankshaft end play (Refer to «CRANKSHAFT»(ref-306143-S14723573232008120900000) )
10. Install connecting rods and measure side clearance. See «STANDARD PROCEDURE»(ref-306143-S16769652082008120900000).
11. Install windage tray. Lubricate bolts with engine oil and tighten to 27 N.m + 1/4 turn (20 ft. lbs. + 1/4 turn).
12. Install the main cap tie (horizontal) bolts and tighten to 28 N.m (250 in. lbs.). see scheme 262
13. Install rear crankshaft oil seal retainer and oil seal (Refer to «INSTALLATION»(ref-306143-S07088088692008120900000) ).
14. Install oil pump assembly. See «INSTALLATION»(ref-306143-S29951389632008120900000).
15. Install dowel pin in crankshaft. See «INSTALLATION»(ref-306143-S23872412052008120900000).
16. Install crankshaft sprocket. See «INSTALLATION»(ref-306143-S40647239562008120900000).
17. Install timing belt and tensioner. See «INSTALLATION»(ref-306143-S40647239562008120900000).
18. Install front timing belt cover. See «INSTALLATION»(ref-306143-S21750707092008120900000).
19. Install oil pickup tube and tighten bolt to 28 N.m (250 in. lbs.).
20. Install oil pan. See «INSTALLATION»(ref-306143-S29257593452008120900000).
21. Install engine assembly. See «INSTALLATION»(ref-306143-S05654550102008120900000).
22. Fill engine crankcase with proper amount of oil.

Scheme 300

The main bearings use a "select fit" system to achieve proper oil clearances between the bearings and the crankshaft. When main bearings are being selected for a new crankshaft, the block and crankshaft grade identification marks must be used to identify the correct main bearings to use.

Scheme 301

The cylinder block main bearing bore grade codes (1) are located on the left side front of the engine block, just below the cylinder head mounting surface. These grade marks (1, 2, 3, or 4) are read left to right, corresponding to main bearing bore 1, 2, 3, or 4.

The grade marks for the crankshaft are located on the rearmost crankshaft counter weight. The crankshaft journal grade marks (A, B, or C) are read left to right, corresponding with journal number 1, 2, 3, 4. For an example, if the main bore grade on the side of the engine block is 3 and the journal grade on the #9 counterweight of the crankshaft is B, the proper select fit bearing would be a (2) +0.003 mm (+0.0001 in.).

Refer to EXAMPLE ROD BEARING SELECTION DATA table for a more detailed example of how to properly select the main bearings.

Note. Service main bearings have a number from (1-5) marked in ink on the bearing surface. For verification, refer to MAIN BEARING SELECTION CHART for number to size identification.

Scheme 302

The upper main bearing (2) has an oil feed hole and a center groove to allow lubrication of the main journal and must be properly positioned in the block.

MAIN BEARING SELECTION CHART