Ranger 2WD V6-245 4.0L VIN X SFI (1997)
Crankshaft Main Bearing: Testing and Inspection
Fitting
Bore Gauge Method
1. Install bearings in the cylinder block and main bearing caps.
2. Install and tighten main bearing cap bolts to specification.
3. Use a micrometer to measure main bearing journals.
4. Use a bore gauge to measure the inside diameter of each bearing assembly. It may be necessary to measure the outer bearings first, then remove
the main bearing caps and measure the inner bearings.
5. Subtract the maximum measurement for each journal from the minimum measurement of each bearing to determine the minimum oil clearance.
Allowable clearances are 0.013-0.048 mm (0.0005-0.0019 inch).
Plastigage Method
1. Clean crankshaft journals. Inspect journals and thrust faces for nicks, burrs or roughness that would cause premature bearing wear. When replacing
standard bearings with new bearings, it is good practice to fit bearing to minimum specified clearance. If desired clearance cannot be obtained with
a standard bearing, try a 0.050 mm (0.002-inch) undersize bearing set to obtain proper clearance.
2. If fitting main bearing in-vehicle; position a jack under counterweight adjoining bearing which is being checked. Support crankshaft with jack so
its weight will not compress Plastigage and provide an erroneous reading.
CAUTION: Do not position jack under crankshaft pulley. Crankshaft post damage will result.
3. Place a piece of Plastigage D81L-6002-B or equivalent on bearing surface across full width of bearing cup and about 6.35 mm (1/4 inch) off
center.
4. Install main bearing cap and tighten bolts to specification. Do not turn crankshaft while Plastigage is in place.
5. Remove cap. Using Plastigage scale, check width of Plastigage at widest point to get minimum clearance. Check at narrowest point to get
maximum clearance. Difference between reading is taper of journals.
6. If bearing clearance exceeds the specified limits, try using one of the various combinations of undersize bearings as directed by the accompanying
table. Use of any other bearing combination is not recommended. Bearing clearance must be within specified limits. See: Specifications If use of
these bearing combinations does not bring clearance to the desired limits, refinish the crank journal to a standard undersize, and use the
