Pistons
Aluminum alloy piston with flat bottom.
On the bottom of the piston there is a mark for the piston diameter and an arrow for orienting the piston when it is installed in the cylinder, which should be directed towards the camshaft drive. By mass, the pistons of one engine should not differ from each other by more than 4.9 g.
Characteristic | Meaning |
Gap between piston and cylinder, mm | |
nominal | |
| 0,016—0,040 |
| 0,025—0,035 |
maximum allowable in operation | 0,10 |
Piston diameter *
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
nominal | ||||
| 86,98 | 88,968—88,982 | 95,468—95,482 | 93,73 |
| — | 88,978—88,992 | 95,478—95,492 | — |
| — | 88,988—89,002 | 95,488—95,502 | |
1st repair size | ||||
| 87,48 | 89,468—89,482 | 95,968—95,982 | 94,13 |
| — | 89,478—89,492 | 95,978—95,992 | — |
| — | 89,488—89,502 | 96,988—96,002 | — |
2nd repair size | ||||
| 87,98 | 89,968—89,982 | 96,468—96,482 | 94,53 |
| — | 89,978—89,992 | 96,478—96,492 | — |
| — | 89,988—90,002 | 96,488—96,502 | — |
3rd repair size | ||||
| 88,48 | — | — | — |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
nominal | ||||
| 85,98 | 85,98 | ||
| — | — | ||
| — | — | ||
1st repair size | ||||
| 86,48 | 86,48 | ||
| — | — | ||
| — | — | ||
2nd repair size | ||||
| 86,98 | 86,98 | ||
| — | — | ||
| — | — | ||
3rd repair size | ||||
| — | — |
* The difference in values is due to the model year of manufacture.
Piston pins
Piston pin steel, polished, floating. The pin is kept from axial displacement by retaining rings.
Piston pin specifications
Parameter, mm | Engine model | |
M 102.920, M 102.939 | M 102.980, M 102.982 | |
Diameter | ||
| 23,995—24,000 | |
| 15,5 | |
Length | — | |
Clearance between the pin and the bushing of the upper head of the connecting rod | 0,007—0,02 | |
Gap between pin and piston boss | 0,002—0,012 |
Piston rings
Three grooves are machined on the outer surface of the piston for the installation of rings. Assembly position: mark «Thor» should be directed upwards. On M 102 engines, piston rings from the company «Goёtze» or TRW.
Design features of the company's piston rings «Goёtze»
The upper compression ring is cylindrical, with a chamfer on the inner surface, with porous chromium plating of the outer surface. The lower compression ring is tapered, with a shoulder. Oil scraper ring with two chamfers, expanding coil spring and chrome-plated outer surface.
Design features of TRW piston rings
The top compression ring is cylindrical, with a chamfer on the inner surface, with a chrome-plated ground barrel-shaped outer surface. The lower compression ring is tapered, with a shoulder and a barrel-shaped chrome-plated outer surface. Oil scraper ring with two chamfers, with an expanding coil spring and a chrome-plated outer surface.
Characteristics of piston rings
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
Height clearance | ||||
top compression ring | 0,05—0,08 | 0,05—0,085 | 0,050—0,085 | |
lower compression ring | 0,03—0,06 | 0,01—0,03 | 0,03—0,06 | |
oil scraper ring | 0,01—0,04 | 0,01—0,045 | 0,01—0,04 | |
Height clearance limit in operation | ||||
top compression ring | 0,15 | |||
lower compression ring | 0,10 | |||
oil scraper ring | 0,16 | 0,10 | 0,16 | |
Gap in the castle | ||||
top compression ring | 0,30—0,55 | |||
lower compression ring | 0,25—0,45 | |||
oil scraper ring | 0,25—0,50 | |||
Maximum clearance in the lock in operation | ||||
top compression ring | 1,0 | 1,0 | 1,0 | |
lower compression ring | 0,8 | 0,8 | 0,8 | |
oil scraper ring | 0,8 | 0,8 | 0,8 | |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
Height clearance | ||||
top compression ring | 0,050—0,085 | |||
lower compression ring | 0,03—0,06 | |||
oil scraper ring | 0,01—0,04 | |||
Height clearance limit in operation | ||||
top compression ring | 0,15 | |||
lower compression ring | 0,10 | |||
oil scraper ring | 0,16 | |||
Gap in the castle | ||||
top compression ring | 0,30—0,55 | |||
lower compression ring | 0,25—0,45 | |||
oil scraper ring | 0,25—0,50 | |||
Maximum clearance in the lock in operation | ||||
top compression ring | 1,0 | |||
lower compression ring | 0,8 | |||
oil scraper ring | 0,8 |
Connecting rods
Connecting rod I-section steel, forged with replaceable liners. A cap of the lower head of a connecting rod of direct section. To supply oil to the rubbing surfaces, a hole is drilled in the connecting rod rod. By mass, the connecting rods of one engine should not differ from each other by more than 5 g.
Characteristic | Meaning |
Non-parallelism and non-flatness of the holes of the heads when measured at a distance of axes of 100 mm from the rod of the connecting rod, no more than, mm | |
| 0,045 |
| 0,030 |
| 0,040 |
| 0,040 |
Surface roughness of the connection of the piston with the connecting rod, microns | 0,002 |
Run-out of openings of the bottom head of a rod, no more, mm | 0,02 |
Connecting rod specifications
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
Connecting rod diameter | 55,60—55,62 | 51,60—51,619 | 55,60—55,62 | |
Connecting rod diameter | 29,00—29,02 | 27,00—27,021 | 29,00—29,02 | |
Upper Head Sleeve Inner Diameter | 26,012—26,018 | 24,007—24,015 | 26,012—26,018 | |
The distance between the axes of the hole heads | 148,95—149,05 | 144,95—145,05 | 148,95—149,05 | |
Bottom Head Width | 32.08—32,10 | 27,857—27,90 | 32.08—32.10 | |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
Connecting rod diameter | 51,60—51,62 | |||
Connecting rod diameter | 26,00—26,02 | |||
Upper Head Sleeve Inner Diameter | 23,007—23,013 | |||
The distance between the axes of the hole heads | 130,95—131,05 | |||
Bottom Head Width | 27,86—27,89 |
Connecting rod cap bolts
Pull-out bolts.
Characteristic | Meaning |
Thread diameter | М9х1 |
Rod diameter, mm | |
M 102 | |
| 8,3—8,4 |
| 8,0 |
M 115 | |
| 8,3—8,4 |
| 8,0 |
M 110 | |
| 7,3—7,4 |
| 7,1 |
M 123 | |
| 7,3—7,4 |
| 7,1 |
Bolt head height (M 102), mm | 5,0—5,2 |
Thread length (M 102), mm | 40,0 |
Head length (M 102), mm | 51,7—52,0 |
Crankshaft
Crankshaft steel, forged four- (M 123 engine), five- (engines M 102, M 115) or semi-support (engine M 110).
Crankshaft 4-cylinder engines (M 102, M 115) has eight counterweights, 6-cylinder (M 110, M 123) - 12 counterweights.
Characteristic | Meaning |
Permissible end runout of the cheeks of the main bearing, mm | 0,02 |
Radii of fillets of main and connecting rod journals, mm | 2,5—3,0 |
Diameter of the front end of the crankshaft, mm | 29,987—30,000 |
Permissible runout of the front end of the crankshaft, mm | 0,030 |
Diameter of a basic surface of a back epiploon, mm | 92,874—92,928 |
Flange out-of-cylindricality, up to, mm | 0,02 |
Flange runout, up to, mm | 0,012 |
The beating of the main journals (the crankshaft is mounted on the prisms of the necks 1 and 5), up to, mm | |
| 0,07 |
| 0.10 |
Engine crankshaft clearances M 102
Characteristic | Meaning |
Diametral clearance between main journal and liners, mm | |
| 0,025—0,045 |
| 0,070 |
Diametral clearance between the connecting rod journal and liners, mm | |
| 0,030—0,050 |
| 0,070 |
Axial backlash of a cranked shaft, mm | |
| 0,06—0,22 |
| 0,30 |
Axial clearance between connecting rod and crankshaft, mm | |
| 0,11—0,23 |
| 0,50 |
Permissible ovality of main and connecting rod journals in operation, mm | 0,025 |
Permissible taper in operation, mm | |
| 0,010 |
| 0,015 |
Permissible unbalance of the crankshaft in operation, g.cm | 15 |
Crankshaft parameters
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
Diameter of main journals | ||||
nominal | ||||
| 69,95—69,96 | 57,935—57,940 | 69,95—69,96 | |
| * | 57,940—57,945 | * | |
| * | 57,945—57,950 | * | |
| * | 57,950—57,955 | * | |
| * | 57,955—57,960 | * | |
| * | 57,960—57,965 | * | |
1st repair size | 69,70—69,71 | 57,705—57,715 | 69,70—69,71 | |
2nd repair size | 69,45—69,46 | 57,455—57,465 | 69,45—69,46 | |
3rd repair size | 69,20—69,21 | 57,205—57,215 | 69,20—69,21 | |
4th repair size | 68,95—68,96 | 57,955—57,965 | 68,95—68,96 | |
Width of main journals | ||||
nominal | 34,00—34,03 | 28.500-28.521 or 28.600-28.621 | 34,00—34,03 | |
1st repair size | 34,00—34,03 | 28,700—28,721 | 34,00—34,03 | |
2nd repair size | up to 34.60 | 28,900—28,921 | up to 34.60 | |
3rd repair size | up to 34.60 | 29,000—29,021 | up to 34.60 | |
4th repair size | up to 34.60 | * | up to 34.60 | |
The distance between the bearing surfaces of the thrust half rings | ||||
— | 23,979—24,000 | — | ||
Diameter of connecting rod journals | ||||
nominal | 51,97—51,96 | 47,955—47,965 | 51,97—51,96 | |
1st repair size | 51,70—51,71 | 47,705—47,715 | 51,70—51,71 | |
2nd repair size | 51,45—51,46 | 47,455—47,465 | 51,45—51,46 | |
3rd repair size | 51,20—51,21 | 47,205—47,215 | 51,20—51,21 | |
4th repair size | 50,95—50,96 | 46,955—46,965 | 50,95—50,96 | |
Width of crankpins | ||||
nominal | 32,0—32,1 | 27,000—28,034 | 32,0—32,1 | |
repair size | until 32.30 | until 28.30 | until 32.30 | |
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
Diameter of main journals | ||||
nominal | ||||
| 59,95—59,96 | |||
| * | |||
| * | |||
| * | |||
| * | |||
| * | |||
1st repair size | 59,70—59,71 | |||
2nd repair size | 59,45—59,46 | |||
3rd repair size | 59,20—59,21 | |||
4th repair size | 58,95—58,96 | |||
Width of main journals | ||||
nominal | 29,00—29,02 | |||
1st repair size | 29,00—29,02 | |||
2nd repair size | up to 29.60 | |||
3rd repair size | up to 29.60 | |||
4th repair size | up to 29.60 | |||
The distance between the bearing surfaces of the thrust half rings | ||||
— | — | — | ||
Diameter of connecting rod journals | ||||
nominal | 47,95—47,96 | |||
1st repair size | 47,70—47,71 | |||
2nd repair size | 47,45—47,46 | |||
3rd repair size | 47,20—47,21 | |||
4th repair size | 46,95—46,96 | |||
Width of crankpins | ||||
nominal | 28,00—28,08 | |||
repair size | until 28.30 |
Inserts of main and connecting rod bearings
Bearing shell color: blue or grey.
Characteristic | Meaning |
Liner width, mm | |
Engines M 102 and M 115 | |
| 33,80—33,90 |
| 34,40—34,60 |
Engines M 110 and M 123 | |
| 28,78—28,90 |
| 29,40—29,60 |
Bearings for all repair steps are supplied over-width and must be refinished to fit the reground bearing.
Engines of models M 102 of release from July 1986 have the thickness of the main bearing shells increased by 0.003 mm in order to reduce the clearance and reduce noise during engine operation.
Characteristics of the liners of main and connecting rod bearings
Parameter, mm | Engine model | |||
M 115.938 | M 102.920, M 102.939 | M 102.980, M 102.982 | M 115.954 | |
Main bearing shell thickness | ||||
nominal | 2,25 | 2,25 | 2,25 | |
1st repair size | 2,37 | 2,37 | 2,37 | |
2nd repair size | 2,50 | 2,50 | 2,50 | |
3rd repair size | 2,62 | 2,62 | 2,62 | |
4th repair size | 2,75 | 2,75 | 2,75 | |
Conrod bearing shell thickness | ||||
nominal | 1,80 | 1,80 | ||
1st repair size | 1,92 | 1,92 | ||
2nd repair size | 2,05 | 2,05 | ||
3rd repair size | 2,17 | 2,18 | 2,17 | |
4th repair size | 2,30 | 2,30 | ||
Parameter, mm | M 123.920, M 123.921 | M 110.923 | M 110.984, M 110.988 | |
Main bearing shell thickness | ||||
nominal | 3,50 | |||
1st repair size | 3,63 | |||
2nd repair size | 3,75 | |||
3rd repair size | 3,88 | |||
4th repair size | 4,00 | |||
Conrod bearing shell thickness | ||||
nominal | 1,81 | |||
1st repair size | 1,93 | |||
2nd repair size | 2,06 | |||
3rd repair size | 2,18 | |||
4th repair size | 2,31 |
M 102 engine flywheel
The flywheel is attached with eight bolts. The mounting hole is opposite the drilling in the crankshaft.
Characteristic | Meaning |
Diameter of the centering collar of the crown, mm | 275,31—275,39 |
Distance between the working surface of the driven disk and the bearing surface of the clutch cover, mm | 22,5—22,6 |
Distance between the working surface of the driven disk and the head of the flywheel mounting bolt, mm | |
| 16,6 |
| 15,5 |
Non-flatness of the working surface of the driven clutch disc, no more than, mm | 0,05 |
Outer diameter of the working surface of the driven clutch disc, mm | 222,0 |
Outer diameter of bearing surface of clutch cover, mm | 253,0 |
Diameter of the shaft of compensation bolts for fastening the flywheel, mm | |
| 8,5 |
| 8,0 |
Bolt length to head, mm | |
| 22±0,2 |
| 22,5 |