Replacing Crankshaft
REPLACING CRANKSHAFT- CRANKSHAFT REMOVED -
- M50 / M50TU -
Note:
Replacement crankshafts are supplied complete with corresponding main and connecting-rod bearing shells.
Crankshaft identification cast on crank cheek.
- Engine M50 B20 = 66 mm stroke
- Engine M50 B25 = 75 mm stroke
The crankshaft is surface treated and may only be reground in the factory.
Reground crankshafts are marked with stripes of paint.
1 - coat of paint: Size 1(0.25 mm)
2 - coats of paint: Size 2 (0.50 mm)
Cars with manual transmission:
Install guide bearing for transmission main shaft.
Drive in pilot bearing with special tool 11 2 030 in conjunction with special tool 00 5 500 (handle).
Crankshafts are marked with yellow, green or white paint depending on main-bearing-journal tolerances.
Bearing shells are marked with yellow, green or white paint.
1. Bearing shell 1-2-3-4-5-7
2. Bearing shell 6 (thrust bearing)
Check grinding size of main-bearing journals!
Installing procedure:
Only place bearing shells with "yellow" colour code in the
crankcase (regardless of paint mark still on the crankcase).
Bearing shells in bearing covers.
Install "yellow or green or white" bearing shells in bearings
caps depending on the crankshaft bearing journal colour code mark.
Installation:
Ensure that the oil spray jets are used at bearings 2... 7.
Install crankshaft.
Place Plastigage (TYPE PG-I) - source of supply:
Cartool - on crankshaft wiped clean of oil and tighten bearing covers as specified. Do not turn crankshaft.
Remove bearing covers and read bearing clearance, according to width of the flattened Plastigage with help of the supplied scale.
Install new bearing shells, bearing shells of different machined size or bearing shells with a different colour code to correct bearing play.
Overview of colour code/shaft diameter/bearing-shell thickness.
Triple-classification colour codes:
Ge = Yellow
Gn = Green
Ws = White
1. Crankshaft
2. Bearing play
3. Bearing-shell thickness
4. Journal diameter
Replacing conrod bearing shells:
Red or blue conrod bearing shells are installed as standard depending on the paint mark on the connecting rod for a relevant crankshaft grinding size.
Install only red bearing shells of the relevant grinding size for replacement crankshafts.
Installation:
Check conrod-bearing play.
Place Plastigage (Type PG 1) - source of supply: Cartool - on crankshaft wiped clean of oil in BDC position.
Mount conrod-bearing caps and tighten with old conrod bolts tightened to specified torque.
Attention!
Do not turn the connecting rods or crankshaft. Remove bearing covers and read bearing play by measuring width of the flattened Plastigage with help of the supplied scale. Specified values: 0.020... 0.055 mm.
Install new bearing shells or bearing shells with a different colour code to correct the bearing play.
Summary:
Colour code/shaft diameter/bearing-shell thickness.
Double-classification colour codes:
Rt = Red
BI = Blue
1. Crankpin
2. Bearing play
3. Bearing-shell thickness
4. Conrod eye
Tightening procedures for main-bearing cap:
Tighten bolts (washed and lubricated with oil) in two steps.
First step tightening torque 23 Nm (17ft.lbs.)
Second step torque angle 50°
connecting-rod-bearing-cap bolt tightening procedure:
Lubricate conrod bearing shells with oil and mount bearing covers so that pair numbers are opposite each other. Use new conrod bolts.
Tighten connecting-rod bolts in two steps.
First step tightening torque 5 Nm (3.5ft.lbs.)
Second step tightening torque 20 Nm. (15Ft.Lbs.)
Torque angle 70°