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Crankshaft - refitting and main bearing running clearance check
Engine removal and general engine overhaul procedures / Crankshaft - refitting and main bearing running clearance check


1 Crankshaft refitting is the first major step in engine reassembly. It is assumed at this point that the cylinder block/crankcase and crankshaft have been cleaned, inspected and repaired or reconditioned as necessary.

Position the engine upside-down.

2 Remove the main bearing cap bolts, and lift out the caps. Lay the caps out in the proper order, to ensure correct installation.

3 If theyre still in place, remove the old bearing shells from the block and the main bearing caps. Wipe the bearing recesses of the block and caps with a clean, lint-free cloth. They must be kept spotlessly-clean!

Main bearing running clearance check
4 Clean the backs of the new main bearing shells. Fit the shells with an oil groove in each main bearing location in the block; note the thrustwashers integral with the No 3 (centre) main bearing upper shell. Fit the other shell from each bearing set in the corresponding main bearing cap. Make sure the tab on each bearing shell fits into the notch in the block or cap. Also, the oil holes in the block must line up with the oil holes in the bearing shell (see illustration).

17.4 Tab on each bearing shell must engage with notch in block or cap, and
17.4 Tab on each bearing shell must engage with notch in block or cap, and oil holes in upper shells must align with block oilways

Caution: Dont hammer the shells into place, and dont nick or gouge the bearing faces. No lubrication should be used at this time.

5 Clean the bearing surfaces of the shells in the block and the crankshaft main bearing journals with a clean, lint-free cloth. Check or clean the oil holes in the crankshaft, as any dirt here can go only one way - straight through the new bearings.

6 Once youre certain the crankshaft is clean, carefully lay it in position in the main bearings.

Trim several pieces of the appropriate-size Plastigage (they must be slightly shorter than the width of the main bearings), and place one piece on each crankshaft main bearing journal, parallel with the crankshaft centre-line (see illustration).

17.6 Lay the Plastigage strips (arrowed) on the main bearing journals,
17.6 Lay the Plastigage strips (arrowed) on the main bearing journals, parallel to the crankshaft centre-line

7 Clean the bearing surfaces of the cap shells, and install the caps in their respective positions (dont mix them up) with the arrows pointing to the timing belt end of the engine.

Dont disturb the Plastigage (see illustration).

17.7 Refit the main bearing caps and tighten the bolts as specified
17.7 Refit the main bearing caps and tighten the bolts as specified

8 Working on one cap at a time, from the centre main bearing outwards (and ensuring that each cap is tightened down squarely and evenly onto the block), tighten the main bearing cap bolts to the specified torque wrench setting. Dont rotate the crankshaft at any time during this operation!

9 Remove the bolts, and carefully lift off the main bearing caps. Keep them in order. Dont disturb the Plastigage or rotate the crankshaft. If any of the main bearing caps are difficult to remove, tap them gently from sideto- side with a soft-faced mallet to loosen them.

10 Compare the width of the crushed Plastigage on each journal with the scale printed on the Plastigage envelope to obtain the main bearing running clearance (see illustration). Check the Specifications to make sure that the clearance is correct.

17.10 Compare the width of the crushed Plastigage to the scale on the
17.10 Compare the width of the crushed Plastigage to the scale on the envelope to determine the main bearing oil clearance (always take the measurement at the widest point of the Plastigage). Be sure to use the correct scale; Imperial and metric scales are included

11 If the clearance is not as specified, seek the advice of a Ford dealer or similar engine reconditioning specialist - if the crankshaft journals are in good condition (see Section 13), it may be possible simply to renew the shells to achieve the correct clearance. If this is not possible, the crankshaft must be reground by a specialist who can supply the necessary undersized shells. First though, make sure that no dirt or oil was between the bearing shells and the caps or block when the clearance was measured. If the Plastigage is noticeably wider at one end than the other, the journal may be tapered (see Section 13).

12 Carefully scrape all traces of the Plastigage material off the main bearing journals and the bearing surfaces. Be very careful not to scratch the bearing - use your fingernail or the edge of a credit card.

Final refitting
13 Carefully lift the crankshaft out of the engine. Clean the bearing surfaces of the shells in the block, then apply a thin, uniform layer of clean molybdenum disulphide-based grease, engine assembly lubricant, or clean engine oil to each surface (see illustration).

Coat the thrustwasher surfaces as well.

17.13 Ensure bearing shells are absolutely clean, lubricate liberally . . .
17.13 Ensure bearing shells are absolutely clean, lubricate liberally . . .

14 Lubricate the crankshaft oil seal journals with molybdenum disulphide-based grease, engine assembly lubricant, or clean engine oil.

15 Make sure the crankshaft journals are clean, then lay the crankshaft back in place in the block (see illustration). Clean the bearing surfaces of the shells in the caps, then lubricate them. Install the caps in their respective positions, with the arrows pointing to the timing belt end of the engine.

17.15 . . . and refit the crankshaft
17.15 . . . and refit the crankshaft

16 Working on one cap at a time, from the centre main bearing outwards (and ensuring that each cap is tightened down squarely and evenly onto the block), tighten the main bearing cap bolts to the specified torque wrench setting.

17 Rotate the crankshaft a number of times by hand, to check for any obvious binding.

18 Check the crankshaft endfloat (see Section 10). It should be correct if the crankshaft thrust faces arent worn or damaged, and if the No 3 (centre) main bearings upper shell has been renewed.

19 Refit the crankshaft left-hand oil seal carrier, and install a new seal (see Part A of this Chapter, Section 20).


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