Measuring, honing and silicon-lapping cylinder bores (engine 119) - RA01001191120X(01-1120)

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MATCHING PISTONS TO CRANKCASE WITH NUMERICAL IDENTIFICATION

Engine 119.960/970/972/974

Class identification

Index

Piston Ø⁽¹⁾

Cylinder Ø⁽²⁾

96.483-96.493

96.498-96.503

96.488-96.498

96.503-96.508

Standard size Std 96.5 Ø

96.493-96.503

96.508-96.513

96.498-96.508

96.513-96.518

96.503-96.513

96.518-96.523

96.983-96.993

96.998-97.003

1st repair size+0.5

96.993-97.003

97.008-97.013

97.003-97.013

97.018-97.023

97.483-97.493

97.498-97.503

2nd repair size+1.0

97.493-97.503

97.508-97.513

97.503-97.513

97.518-97.523

⁽¹⁾	Group identification stamped on piston crown with color.

⁽²⁾	Group identification stamped at top next to cylinder bore.

MATCHING PISTONS TO CRANKCASE WITH LETTER IDENTIFICATION

Engine 119.980/982/970/972/974

Group identification

Index

Piston Ø⁽²⁾

Cylinder Ø⁽¹⁾

96.482-96.495

96.500-96.508

Standard size Std 96.5 Ø

96.491-96.504

96.508-96.516

96.499-96.512

96.516-96.524

96.982-96.995

97.000-97.008

1st repair size +0.5

96.991-97.004

97.008-97.016

96.999-97.012

97.016-97.024

97.482-97.495

97.000-97.508

2nd repair size +1.0

97.491-97.504

97.508-97.516

97.499-97.512

97.516-97.524

⁽¹⁾	Group identification stamped at top next to cylinder bore.

⁽²⁾	Group identification stamped on piston crown.

MATCHING PISTONS TO CRANKCASE WITH NUMERICAL IDENTIFICATION

Engine 119.971/975/981/985

Group identification

Index

Piston Ø⁽¹⁾

Cylinder Ø ⁽²⁾

91.983-91.993

91.998-92.003

91.988-91.998

92.003-92.008

Standard size Std 92.0 Ø

91.993-92.003

92.008-92.013

91.998-92.008

92.013-92.018

92.003-92.013

92.018-92.023

92.483-92.493

92.498-92.503

1st repair size +0.5

92.493-92.503

92.508-92.513

92.503-92.513

92.518-92.523

92.983-92.993

92.998-93.003

2nd repair size +1.0

92.993-93.003

93.008-93.013

93.003-93.013

93.018-93.023

⁽¹⁾	Group identification stamped on piston crown with color.

⁽²⁾	Size stamped at top next to cylinder bore.

MATCHING PISTONS TO CRANKCASE WITH LETTER IDENTIFICATION

Engine 119.971/975/981/985

Group identification

Index

Piston Ø ⁽²⁾

Cylinder Ø ⁽¹⁾

91.982-91.995

92.000-92.008

Standard size Std 92.0 Ø

91.991-92.004

92.008-92.016

91.999-92.012

92.016-92.024

92.482-92.495

92.500-92.508

1st repair size +0.5

92.491-92.504

92.508-92.516

92.499-92.512

92.516-92.524

92.982-92.995

93.000-93.008

2nd repair size +1.0

92.991-93.004

93.008-93.016

92.999-93.012

93.016-93.024

⁽¹⁾	Group identification stamped at top next to cylinder bore.

⁽²⁾	Group identification stamped on piston crown.

Piston clearance	When new	0.004-0.026
Piston clearance	Wear limit	0.08
Maximum wear limit of cylinder bores in direction of travel or transverse direction at top and bottom reversal point of 1st piston ring		0.10

MACHINING TOLERANCES

Permissible variation of cylinder shape	When new	0.013
	Wear limit	0.05
Permissible variation of rectangularity related to cylinder height		0.05
Averaged peak-to-valley height (Rz) after polishing		0.001
Averaged peak-to-valley height (Rz) after silicon-lapping		0.001 - 0.003
Permissible wave depth (Wt)	50 % of peak-to-valley height after silicone-lapping
Chamfer of cylinder bores		see ill. step 14

NOTE: See pistons, matching and dimensions for further tolerances and assignments.

COMMERCIAL TOOLS

Automatic cylinder repair machine
SUNNEN CK-10-G with honing oil filter and oil cooler
or CV 616

Honing head CK-3000 for dia. 76-127 mm or CK-2600

SUNNEN honing oil MB 30⁽¹⁾

Germany:

Prehoning stone set C 30-A 53, 70 mm long⁽²⁾

e.g. Hommel Handel GmbH

Final honing stone set C 30-J 84, 70 mm long ⁽²⁾

Donatusstraβe 24, D-5000 Koln 71

Polishing stone set C 30-C 03-81

Stone holder for felt insert CK-30 35

other countries:
e.g. SUNNEN Products Comp.

Felt insert holder set CK-3130

USA-7910 Manchester
St. Louis, Mo. 63143

Felt insert C 30-F 85

SUNNEN silicon paste AN-30

Hommel Handel Export Division

Box for silicon paste and felt inserts AN-35

P.O. Box 1206 D-6806 Viernheim

Internal measuring instrument for 50 - 150 mm dia., with 0.01 mm indication and measuring point pressure relief, e. g. SUNNEN GRM 2125

Setting micrometer for internal measuring instrument GAM 2125 with setting range 50 - 200 mm, e.g. SUNNEN CF-1000 M

⁽¹⁾	When refilling approx. 170 liters.

⁽²⁾	These stones are available only with a length of 89 mm and must be shortened at the top to 70 mm with a hacksaw (see step 3).

NOTE: The light alloy cylinder bores are very sensitive to damage, scratching and also dirt and must therefore be handled with grate care.

The cylinder bores should be adapted when honing to the sizes of the available repair size pistons with the Group No. 0, 1 or 2. The specified piston clearance must be observed.

Measuring

Use a measuring instrument with measuring point pressure relief for measuring the cylinder bores as the cylinder barrel will otherwise be scored by the measuring point tip and the measuring point tip of the instrument will wear prematurely.

Set the self-centering internal measuring instrument to the cylinder dia. before measuring. Measure the cylinder bores at a room temperature of 22 - 24 °C.

Fig 1: Identifying Internal Measuring Instrument And Setting Micrometer

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Following silicon-lapping (final state) it is only possible to measure the amount by which the aluminum surfaces stand back between the silicon crystals (0.5 -1.5 μm) indirectly by means of the averaged peak-to-valley height (Rz).

The specified exposed depth of the silicon crystals results from the limited-time control during silicon-lapping and from the silicon paste used.

Honing and silicon-lapping

Where severe scoring and severe cylinder wear exists (> 0.10 mm) etc., the cylinder bores can be honed to the stated repair sizes.

The silicon crystals must be undamaged and be flattened on the cylinder surface following the honing operations.

After the honing operations (prehoning, final honing and polishing) it is essential to perform "silicon-lapping" based on the Sunnen method so that the silicon crystals are exposed.

If the "silicon-lapping" operation is not performed, this will inevitably result in piston seizure .

The following operations can only be performed with a honing machine with honing oil filter and oil cooler.

The silicon particles must be filtered out of the honing oil.

The honing oil must be cooled to a constant temperature of 20 °C to avoid excessive heating of the crankcase.

Only the specified honing oil may be used to achieve good honing quality.

Prepare honing machine CK-10-G.
Perform all the honing and lapping operations without the direction guide shoes.

The honing stone runout (arrow) size x:

Engine 119.96 14 mm

Engine 119.97 13.5 mm

Fig 2: Identifying Honing Stone Runout Size
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Cut off projection of bronze bars at bottom of main guide shoe (arrow) as only approx. 14 mm undercut for the honing stone runout is available at the cylinders.

Fig 3: Locating Projection Of Bronze Bars At Bottom Of Main Guide Shoe
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
The specified stone sets of 89 mm length must be shortened to 70 mm. Only the honing stone, not the holder, should be cut off at the top with a hacksaw.

Fig 4: Identifying Honing Stone Length
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Tighten crankshaft bearing cap bolts and nuts to 50 Nm in the order of the tightening diagram.

Fig 5: Identifying Crankshaft Bearing Cap Bolts And Nuts Tightening Sequence
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Fix disassembled and cleaned crankcase with crankshaft bearing caps installed and tightened in the honing machine with the square steel bar (1).

Fig 6: Identifying Steel Bar
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Set stroke setting (cylinder length) on the stroke scale (arrow) according to the "prehoning" table.

Fig 7: Locating Stroke Setting (Cylinder Length) On Stroke Scale
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Set stone projection (arrow) with the gauge according to the table.

Fig 8: Locating Stone Projection
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Set feed (arrow) according to table.

Set strokes/min and rpm according to table.

Fig 9: [Locating Feed]

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Prehoning

SETTING OF HONING MACHINE

Engine	119.960	119.970 119.974		119.971
Cylinder dia. setting for 1st repair size (+0.5)	96.5 mm	96.5 mm		92.0 mm
Cylinder length (L)	154 mm		137.5 mm
Stroke setting	156 mm		140 mm
Revolutions/min		125
Strokes/min		49 (CK-10-G) 57 (CV616)
Feed		4
Stone projection		approx. 12 mm
Prehoning stone set		C 30-A 53 (C30-J55)
Indication %		approx. 30
Stock removal/min		0.07 mm
Feed scale/stock removal		10 graduations/0.05 mm

Prehone all the cylinder bores at full honing oil feed up to approx. 0.08 mm before final size otherwise the silicon crystals will be torn out or destroyed by the cutting pressure.
A deviation of approx. +0.02 mm is obtained when measuring immediately after prehoning as a result of heating.

The heating of the crankcase is dependent among other things on the outside temperature.
Insert stone set for final honing and cut to length as described in step 3.

Set honing machine according to the "precision honing" table.

Precision honing

SETTING OF HONING MACHINE

Engine	119.960	119.970 119.974		119.971
Cylinder dia. setting for 1st repair size (+0.5)	96.92 mm	96.92 mm		92.42 mm
Cylinder length (L)	154 mm		137.5 mm
Stroke setting	156 mm		140 mm
Revolutions/min		125
Strokes/min		49 (CK-10-G) 57 (CV616)
Feed		3
Stone projection		approx. 12 mm
Precision honing stone set		C 30-J 84
Indication %		approx. 30
Stock removal/min		0.05 mm
Feed scale/stock removal		10 graduations/0.05 mm

Precision-hone all cylinder bores at full honing oil feed up to approx. 0.02 mm before final size.
A deviation of approx. +0.01 mm is obtained when measuring directly after precision-honing as a result of heating. Heating of the crankcase is dependent among other things on the outside temperature.
Chamfer cylinder bores according to the sketch prior to "polishing".

Fig 10: Identifying Cylinder Bore Dimension
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
For chamfering, use a suitable handmilling cutter with an angle as shown in the sketch above.

Fig 11: Chamfering Cylinder Bore Using Handmilling Cutter
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Insert stone set for polishing.
New polishing stones should be corrected in the tightest cylinder bore before starting machining.

Set honing machine according to "polishing" table.

Polishing

SETTING OF HONING MACHINE

Engine	119.960	119.970 119.974		119.971
Cylinder dia. setting for 1st repair size (+0.5)	96.98 mm	96.98 mm		92.48 mm
Cylinder length (L)	154 mm		137.5 mm
Stroke setting	156 mm		140 mm
Revolutions/min		125
Strokes/min		49 (CK-10-G) 57 (CV616)
Feed		2
Stone projection		approx. 12 mm
Polishing stone set		C 30-C 03-81
Indication %		approx. 30
Stock removal/min		0.01 mm
Feed scale/stock removal		10 graduations/0.01 mm

Polish all cylinder bores at full honing oil feed up to end size.
Allow crankcase to cool.
Measure cylinder bores.
When performing this step, allow for the required cylinder dia. (Group No.) for the existing pistons and the specified piston clearance.

Re-polish once again if necessary.

Fig 12: Measuring Cylinder Bore
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Clean cylinder walls with filtered honing oil so that all silicon particles are removed and do not cause any scratches during the subsequent silicon-lapping operation.
Press felt inserts C 30-F 85 into the holders CK-3130 and the latter into the stone holders CK-3035.

After pressing in the felt inserts, remove all material deposits on the holder.

Fig 13: Pressing Felt Inserts C 30-F 85 Into Holders Ck-3130
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Perform setting of cylinder diameter with the setting gauge.

Fig 14: Setting Of Cylinder Diameter With Setting Gauge
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Soak felt inserts with filtered honing oil and insert into the honing head.
Shut off honing oil feed.

Set honing machine according to "silicon lapping" table.

Silicon-lapping

SETTING OF HONING MACHINE

Engine	119.960	119.970 119.974		119.971
Cylinder dia. setting for 1st repair size (+0.5)	97 mm	97 mm		92.5 mm
Cylinder length	154 mm		137.5 mm
Stroke setting	140 mm		124 mm
Revolutions/min		185 (CK-10-G) 230 (CV616)
Strokes/min		73 (CK-10-G) 80 (CV616)
Infeed		2
Felt insert projection		2 mm
Felt insert		C 30-F 85
Indication %		ca. 30
Stock removal/min		not measurable
Feed scale		18 graduations approx. 70 seconds operation

Thoroughly stir AN-30 silicon paste and then rub into the dry cylinder walls fully.
Likewise apply silicon paste to felt inserts.
Introduce honing head with felt inserts into cylinder bore.
With honing machine running, slowly turn the feed wheel to the right until the indicating instrument has reached 30 %.

Fig 15: [Identifying Instrument Indication Value]
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Set feed scale to 18 graduations.
The honing machine switches off after approx.

70 seconds. The cylinder surface then has a mat appearance.

No honing angle is visible.

The peak-to-valley height is 0.001 - 0.003 mm.

Fig 16: Identifying Honing Machine
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
Thoroughly clean all silicon paste residues from cylinder bores with filtered honing oil and a suitable soft-bristle brush and dry cylinder bores.
Used silicon paste must not be re-used!

Fig 17: Cleaning Silicon Paste Residues From Cylinder Bores With Soft-Bristle Brush
Courtesy of MERCEDES-BENZ OF NORTH AMERICA.