Mercedes-Benz ML320. Manual — part 431

Commercially available tools

Workshop equipment

3

Machin valve seat
ring in cylinder head

*WE58.40-Z-
1009-21A

*WE58.40-Z-
1010-21A

Observe tool manufacturer's operating instructions, maintain

dimensions in accordance with checking and machining
dimensions. ?

Checking and machining dimensions for valve seats

AR05.30-P-
4510-01AV

If the measurements after machining are less than the

specification ?

Replace valve seat ring.

AR05.30-P-
3831AV

Inspection

4 Measure seat width

Correct valve seat width if necessary.

AR05.30-P-
4510-01AV

5

Insert valve and
inspect for leaks

Grind valve with valve grinding compound before

installation.

*WH58.30-Z-
1020-13A

6

Measure valve set-
back to cylinder head

If measurement is less than minimum dimension no further

correct valve clearance compensation is possible; replace valve
seat ring or cylinder head ?

AR05.30-P-
4100-01AV

Replace valve seat ring. ?

The valve must always be replaced after installing a new

valve seat ring.

AR05.30-P-
3831AV

Install

7 Install valves

AR05.30-P-
3511AV

Number

Designation

WH58.30-Z-1020-13A

Vacuum testing unit

WE58.40-Z-1009-21A

Valve seat turning device

WE58.40-Z-1010-21A

Valve seat turning device

2004 Mercedes-Benz ML350

1998-2005 ENGINE Engine timing - 163 Chassis

me

1998-2005 ENGINE

Complete engine - 163 Chassis

GENERAL INFORMATION

DETERMINE LOSS OF PRESSURE AT CYLINDER - AH01.00-N-1300-02A

All engine

If an increased pressure loss was found with the cylinder leak tightness tester, inspect engine by listening at
cylinder head gasket, air intake area, exhaust, oil filler opening and prechamber or spark plug bores of the
adjacent cylinder or cylinders.

Check the coolant in the coolant expansion reservoir for the formation of air bubbles.

Possible causes for the pressure loss are:

1. Outlet of air through prechamber or spark plug bore of adjacent cylinder or cylinders, air bubbles

in coolant expansion reservoir:

pressure loss at cylinder head gasket

2. Outlet of air through air intake area:

For inspecting by listening, open throttle valve pressure loss at inlet valve(s)

3. Outlet of air through exhaust:

pressure loss at exhaust valve(s)

4. Outlet of air through oil filler opening:

pressure loss through pistons and piston rings

It is possible to pinpoint the pressure loss of the relevant cylinder by spraying with engine oil. Engine oil

seals off the gap between piston and cylinder briefly.

If a reduced pressure loss now occurs for a short time, the cause is very likely to be at the pistons, piston rings
or cylinder contact surface of the relevant cylinder.

Determining the cause can be falsified by the position of the piston ring joints. If suspicion exists that the loss of
pressure is caused by the piston ring joints being positioned directly one above the other, fit parts to engine and
repeat test after running engine for a short time.

GENERAL INFORMATION ON INSPECTING CYLINDER WALLS - AH01.00-P-0300-01A

2001 Mercedes-Benz ML320

1998-2005 ENGINE Complete engine - 163 Chassis

2001 Mercedes-Benz ML320

1998-2005 ENGINE Complete engine - 163 Chassis

me

me

Engine 112, 113, 122, 134, 135, 137, 166, 275, 285, 611, 612, 613, 628, 629, 639, 642, 646, 647, 648

Pressure gloss marks, smoothings

Individual blank points, e.g. in the middle of the cylinder barrel or around the cylinder head bolts.

The crankcase can be reused.

Fig. 1: Identifying Pressure Gloss Marks On Cylinder Walls

Visible mottling, friction marks

Starting from reverse area of the upper piston ring tapering down.

Traces of dry rubbing which cannot be felt, caused by oil film being washed off by fuel, for example from many
cold starts when driving for short distances.

These traces of friction occurring mainly around the cylinder head bolts and on the pressure side are not a
problem provided that they are smoothed out.

The piston rings are not damaged.

The crankcase can be reused.

2001 Mercedes-Benz ML320

1998-2005 ENGINE Complete engine - 163 Chassis

me

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