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Diesel engines for trucks and tractors. Spare parts, adjustments and repairs.
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Diesel engine YaMZ-7511
The YaMZ-7511 diesel engine manufactured by the Yaroslavl Motor Plant is designed for heavy-duty MAZ vehicles and special equipment and has good fuel-economic, efficient and operational characteristics. The environmental standard of the motor complies with EURO-2.
The appearance of the YaMZ-7511.10 diesel engine with individual cylinder heads and a lamellar liquid-oil cooler (LMO) is shown in Figure 1.
Figure 1 - YaMZ-7511 power unit with individual cylinder heads
Technical characteristics of the YaMZ-7511 diesel engine
Engine type - Four-stroke with compression ignition and turbocharging
Number of cylinders - 8
The arrangement of the cylinders is V-shaped, the camber angle is 90 degrees
Cylinder firing order - 1-5-4-2-6-3-7-8
Direction of rotation of the crankshaft - Right
Cylinder diameter, mm - 130
Piston stroke, mm - 140
Working volume, l - 14.86
Compression ratio - 16.5
Rated power, kW (hp) - 294 (400)
The frequency of rotation of the crankshaft at rated power, min-1 - 1900
Maximum torque, Nm (kgsm) - 1715 (175)
Rotational speed at maximum torque, min-1 - 1100-1300
Idling speed, min-1:
Maximum - 2150
- minimum - 600±50
Specific fuel consumption by speed characteristic, g/kWh (g/l.s.h):
Minimum - 194 (143)
- at rated power - 215 (158)
Specific oil consumption for waste in % of fuel consumption, not more than - 0.2
Mixing method - Direct injection
Combustion chamber - Undivided type in the piston
Camshaft - Common for both rows of cylinders, gear driven
Valve timing:
Intake valves - opening, deg. to TDC - 21.5 / closing, deg. after NMT - 31.5
- exhaust valves - opening, deg. to TDC - 63 / closing, deg. after BMT - 29.5
Number of valves per cylinder - One intake and one exhaust
Thermal valve clearances on a cold engine, mm - 0.25-0.30
YaMZ-7511 diesel lubrication system
Type - Mixed, with oil cooling in a liquid-oil heat exchanger (LMT): bearings of the crankshaft, camshaft, rocker axles, high-pressure fuel pump, turbocharger are lubricated under pressure; other rubbing surfaces are lubricated by spraying.
Oil pump - Gear type, single section
Oil pressure in a warm engine in the block line kPa (kgf/cm2):
At rated speed - 400-700 (4-7)
- at minimum speed, not less than - 100 (1)
Oil filters - Two: a full-flow fine oil filter (PFTOM) with a replaceable filter element and a centrifugal oil cleaner (CM)
Oil cooling system - With a liquid-oil heat exchanger (LMO), which is installed on the engine, plate or tubular type
Piston oil cooling system - Nozzles for jet oil cooling of pistons with holes with a diameter of 2.5 mm are located on pipes on the right and left sides of the engine with oil withdrawal through a throttle bushing with a diameter of 6 mm in the area of the engine lubrication system between the ZHMT and PFTOM.
Oil pressure at the start of opening the valves of the lubrication system, kPa (kgf/cm2):
Oil pump pressure reducing valve - 700-800 (7.0-8.0)
- differential valve - 490-520 (4.9-5.2)
- oil filter bypass valve - 200-250 (2.0-2.5)
- signaling device for opening the bypass valve of the oil filter - 180-230 (1.8-2.3)
- bypass valve ZhMT 274±25 (2.8±0.25) (only for lamellar type ZhMT)
Fuel system of YaMZ-7511.10 engine
Type - Divided type
High pressure fuel pump with a regulator and a fuel priming pump - Eight-section, plunger, spool-type plungers.
High pressure fuel pump model - 175.1111005-40
The order of operation of the fuel pump sections is 1-3-6-2-4-5-7-8
Speed regulator - Centrifugal, all-mode
Fuel priming pump - Piston with manual fuel pump
Nozzles - Closed type, with multi-hole atomizers: on engines with common heads - 267.1112010-02 or 204.1112010-50.01 / on engines with individual heads - 51.1112010-01
Adjusting fuel injection advance angle (It is set according to the marks on the flywheel and the injection pump housing):
On engines with common heads - (6 + 1) degrees
- on engines with individual heads - (8 + 1) degrees
Fuel filters:
Coarse cleaning - Settling filter
- fine cleaning - With a replaceable filter element. On the cover is a bypass valve-jet. Valve-jet opening pressure 20-40 (0.2-0.4) kPa (kgf/cm2)
Supercharging system - Gas turbine single turbocharger with radial centripetal turbine and centrifugal compressor
Turbocharger - Model 122 (YaMZ)
Boost pressure (excessive) at nominal operation, kPa (kgf / cm2) - 125 (1.25)
Cooling system of the YaMZ-7511 diesel engine
Type - Liquid, closed type, with forced circulation of the coolant.
The cooling system is equipped with a thermostatic device to automatically maintain the thermal regime of the engine.
Water pump - Centrifugal type, belt driven. Fan - Six-bladed, with gear drive and friction clutch for turning on the fan.
Liquid-oil heat exchanger - Plate or tubular type. Equipped with a faucet or plug for draining the coolant.
Thermostats - Solid filled. Opening start temperature 80 C.
electrical equipment
Type - Single-wire circuit. Rated voltage 24 V. Generator - Alternating current, with a two-strand belt drive, with a rated voltage of 28 V.
The generator model is determined by the configuration. Starter - Electric starter mod. 25.3708-21 or 4581 (Slovakia), nominal voltage 24 V.
To facilitate starting a cold engine, an electric torch device is provided.
additional characteristics
Clutch - YaMZ-184
Gearbox - YaMZ-239
Refueling capacities, l:
Engine lubrication system - 32
- cooling system (without radiator volume and expansion tank) - 22
Mass of an unfilled power unit with individual cylinder heads, kg:
Without clutch and gearbox - 1250
- with clutch - 1295
- with clutch and gearbox - 1685
Weight of an unfilled power unit with common cylinder heads:
Without clutch and gearbox - 1215
- with clutch - 1260
- with clutch and gearbox - 1635
The YaMZ-7511 engine has been produced by the Yaroslavl Motor Plant since 1996. It is intended for installation on MAZ vehicles. A new generation of 8-cylinder diesel engines of the D x S = 130 x 140 mm family of dimensions - YaMZ-7511 and its modifications - with a power of 360-420 hp. meets the basic technical and economic requirements of modern automotive technology. All models have successfully passed certification tests, which is confirmed by international certificates of compliance with Euro-2 environmental standards. At the same time, design and research work is underway to achieve more stringent Euro-3 standards. Promising engines of this family have a wide range of potential consumers, including the largest manufacturers of cars, main road trains, tractors and other equipment in Russia. Belarus, Ukraine.
Design features: The engine is equipped with "Compact-40" type fuel equipment with increased injection energy up to 1200 kg/cm, fan clutch, crankshaft vibration damper, improved characteristics of inlet and outlet channels. The engine has a built-in liquid-oil heat exchanger, a new cylinder-piston group with a more efficient oil cooling system, an increased performance water pump, an upgraded oil filtration system, etc. It is made for the installation of an air-to-air charge air cooler on a car.
YaMZ-7511.10, YaMZ-7511.10-06, YaMZ-7512.10 engines are four-stroke, compression-ignition, V-shaped cylinders and gas turbine supercharging.
Number of cylinders: 8
Cylinder diameter, mm: 130
Piston stroke, mm: 140
Cylinder displacement, l: 14.86
Compression ratio: 16.5
Engine speed at rated power min -1: 1900 (+50, -20)
Frequency of rotation of the crankshaft at maximum torque, min -1, no more: 1100-1300
Engine idle speed, min:
minimum: 550-650
maximum, no more: 2150
Weight of the unfilled engine in the scope of delivery, kg:
a) with individual cylinder heads
without clutch: 1250
with clutch: 1295
a) with common cylinder heads
without clutch: 1215
with clutch: 1260
SPECIFICATIONS
Mixing method: Direct injection.
Fuel supply equipment: Divided.
High pressure fuel pump: Eight-plunger.
Speed controller: Centrifugal, all-mode with boost corrector.
Nozzles: Closed, with a multi-hole atomizer.
Turbocharger 12.1118010: The turbine is radial centripetal; centrifugal compressor.
Lubrication system: Mixed: under pressure and splashing, with oil cooling in a liquid-oil heat exchanger. In addition, oil is supplied through a system of channels and pipelines for jet cooling of the pistons.
Oil filters: Two: full-flow with replaceable filter elements and jet-driven centrifugal.
Oil pump: Single section, gear type.
Cooling system: Liquid, closed type, with forced circulation of the coolant; equipped with a thermostatic device.
Starting device: Starter 2501.3708-01, direct current, sequential excitation with electromagnetic drive. Rated power 8.2 kW (11 hp), rated voltage 24 V.
Starting aid: Electrical device.
Generator 6582.3701-03: Alternating current with a double-strand belt drive, rated voltage 28 V, with built-in voltage regulator, with a maximum load current of 80 A.
Clutch: YaMZ-184. Diaphragm, single-disk, retractable type.
Transmission: It is possible to install gearboxes manufactured according to the size code No. 1 ISO 7648 (SAE No. 1), or others as agreed with the customer.
The power units are designed for operation at ambient temperatures from minus 60°C to plus 50°C, relative humidity up to 98% at a temperature of 25°C, air dust content up to 0.4 g / m³, as well as for vehicle movement in mountainous conditions at altitude up to 4500 m above sea level and overcoming passes up to 4650 m above sea level with a corresponding decrease in power and economic indicators. The appearance of the YaMZ-7511.10 engine with individual cylinder heads and a lamellar liquid-oil cooler (LMO) is shown in Figure 1, and the comparative performance of engines of the YaMZ-7511 type is shown in Table 1.
Fig.1- YaMZ-7511.10 power unit with individual cylinder heads
| Power unit model | YaMZ - 7511.10 | YaMZ - 7512.10 | YaMZ - 7513.10 | YaMZ - 7514.10 | YaMZ - 7601.10 | |||
| engine's type | Four-stroke, compression-ignition, turbocharged | |||||||
| Number of cylinders | 8 | 6 | ||||||
| Cylinder arrangement | V-shaped, camber angle 90º | |||||||
| The order of operation of the cylinders | 1 - 5 - 4 - 2 - 6 - 3 - 7 - 8 | 1 - 4 - 2 - 5 - 3 - 6 | ||||||
| Cylinder numbering scheme | See fig 2 | |||||||
| Direction of rotation of the crankshaft | Right | |||||||
| Cylinder diameter, mm | 130 | |||||||
| Piston stroke, mm | 140 | |||||||
| Working volume, l | 14,86 | 11,15 | ||||||
| Compression ratio | 16,5 | |||||||
| Rated power, kW (hp) | 294 (400) | 264 (360) | 309 (420) | 277 (375) | 220 (300) | |||
| The frequency of rotation of the crankshaft at rated power, min -1 | 1900 | 1500 | 1900 | |||||
| Maximum torque, N m (kgf m) | 1715 (175) | 1570 (160) | 1813 (185) | - | 1274 (130) | |||
| Rotational speed at maximum torque, min -1 | 1100 - 1300 | - | 1100 - 1300 | |||||
| Idling speed, min -1: | maximum | 2150 | 1650 | 2150 | ||||
| minimal | 600±50 | 950±50 | 600±50 | |||||
| Specific fuel consumption by speed characteristic, g/kW h (g/hp h): | minimum | 194 (143) | 197 (145) | - | 197 (145) | |||
| at rated power | 215 (158) | 208 (153) | 215 (158) | |||||
| Specific oil consumption for waste in % of fuel consumption, no more | 0,2 | |||||||
| speed characteristic | See Figure 3 | See fig 4 | See Figure 5 | - | See Figure 6 | |||
| Mixing method | direct injection | |||||||
| The combustion chamber | Undivided type in the piston | |||||||
| Camshaft | Common to both rows of cylinders, gear driven | |||||||
| Valve timing: | intake valves | opening, hail. up to TDC | 21,5 | |||||
| closing, deg. after BMT | 31,5 | |||||||
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graduation valves |
opening, hail. up to TDC | 63 | ||||||
| closing, deg. after BMT | 29,5 | |||||||
| Number of valves per cylinder | One intake and one exhaust | |||||||
| Thermal valve clearances on a cold engine, mm | 0,25 — 0,30 | |||||||
| Lubrication system | Mixed, with oil cooling in a liquid-oil heat exchanger (LMT): bearings of the crankshaft, camshaft, rocker axles, high-pressure fuel pump, turbocharger are lubricated under pressure; other rubbing surfaces are lubricated by spraying. | |||||||
| Oil pump | Gear type, single section | |||||||
| Oil pressure in a warm engine in the line of the block kPa (kgf / cm 2): | at rated speed |
400 - 700 (4 - 7) |
300 - 600 (3 - 6) | 400 - 700 (4 - 7) | ||||
| at minimum speed, not less than | 100 (1) | |||||||
| Oil filters | Two: a full-flow fine oil filter (PFTOM) with a replaceable filter element and a centrifugal oil cleaner (CM) | |||||||
| Oil cooling system | With a liquid-oil heat exchanger (LMO), which is installed on the engine, plate or tubular type | |||||||
| Piston oil cooling system | Spray nozzles for jet cooling of pistons with oil with ∅2.5mm holes are located on pipes on the right and left sides of the engine with oil extraction through a ∅6mm throttle bushing in the area of the engine lubrication system between ZHMT and PFTOM | |||||||
| Oil pressure at the beginning of the opening of the valves of the lubrication system, kPa (kgf / cm 2): | oil pump pressure reducing valve | 700 - 800 (7,0 - 8,0) | ||||||
| differential valve | 490 - 520 (4,9 - 5,2) | |||||||
| oil filter bypass valve | 200 - 250 (2,0 - 2,5) | |||||||
| signaling device for opening the bypass valve of the oil filter | 180 - 230 (1,8 - 2,3) | |||||||
| bypass valve ZhMT | 274±25 (2.8±0.25) (only for plate type ZHMT) | |||||||
| Fuel supply system | split type | |||||||
| High pressure fuel pump with regulator and fuel pump |
Eight-section, plunger, spool-type plungers. | Six-section, plunger, spool-type plungers. | ||||||
| High pressure fuel pump model | 175. 1111005 - 40 | 175. 1111005 - 60 | 175. 1111005 - 50 | 19E 175. 1111005 | 135. 1111005 - 10 | |||
| The order of operation of the sections of the fuel pump | 1 - 3 - 6 - 2 - 4 - 5 - 7 - 8 | 1 - 2 - 3 - 5 - 4 - 6 | ||||||
| Speed controller | Centrifugal, all-mode | |||||||
| Fuel pump | Piston with manual fuel pump | |||||||
| nozzles | Closed type, with multi-hole atomizers: | on engines with common heads - 267. 1112010 - 02 or 204. 1112010 - 50. 01 | ||||||
| on engines with individual heads - 51. 1112010 - 01 | ||||||||
| Injector injection start pressure, MPa (kgf / cm 2) | 26,5 +0,8 (270 +8) - 267. 1112010 - 02
26,5 +1,2 (270 +12) - 204. 1112010 - 50. 01 26,5 +1,2 (270 +12) - 51. 1112010 - 01 |
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| Adjustable fuel injection advance angle | It is installed according to the marks on the flywheel and the injection pump housing: | on engines with common heads - (6 +1)º | ||||||
| on engines with individual heads - (8 +1)º | ||||||||
| Fuel filters: | coarse cleaning | Settling filter | ||||||
| fine cleaning | With replaceable filter element. On the cover is a bypass valve-jet. Opening pressure of the jet valve 20-40 (0.2-0.4) kPa (kgf / cm 2) | |||||||
| Pressurization system | Gas turbine with one turbocharger with radial centripetal turbine and centrifugal compressor | |||||||
| Turbocharger | Model 122 (YaMZ), K - 36 - 87 - 01 or K36 - 30 - 01 (Czech Republic), TKR - 100 (Turbotechnics) | Model 122 - 07 (YaMZ), TKR - 90 (Turbotechnics) | ||||||
| Boost pressure (excessive) at nominal operation, kPa (kgf / cm 2) | 125 (1,25) | |||||||
| Cooling system | Liquid, closed type, with forced circulation of the coolant. Equipped with a thermostatic device to automatically maintain the thermal mode of the engine | |||||||
| Water pump | Centrifugal type, belt driven | |||||||
| Fan | Six-bladed, with gear drive and friction clutch for turning on the fan | |||||||
| Liquid - oil heat exchanger | Plate or tubular type. Equipped with a faucet or plug for draining the coolant. | |||||||
| thermostats | With solid filler. The opening temperature is 80 ºС. | |||||||
| electrical equipment | Single wire circuit. Rated voltage 24V. | |||||||
| Generator | Alternating current, with a two-strand belt drive, with a rated voltage of 28V. The generator model is determined by the configuration. See package | |||||||
| Starting device | Electric starter mod. 25. 3708 - 21 or 4581 (Slovakia), rated voltage 24V. To facilitate starting a cold engine, an electric torch device is provided. |
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| Clutch | See package | |||||||
| Transmission | See package | |||||||
| Refueling capacity, l | engine lubrication system | 32 | 24 | |||||
| cooling system (without radiator volume and expansion tank) | 22 | 17 | ||||||
| Transmission | See "gearbox" section | |||||||
| The weight of the unfilled power unit in completeness deliveries, kg: |
With individual cylinder heads |
without clutch and box gear |
1250 | 1010 |
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| with clutch | 1295 | - | - | |||||
| 1685 | - | 1385 | ||||||
| With common cylinder heads | without clutch and gearbox | 1215 | - | |||||
| with clutch | 1260 | - | - | |||||
| with clutch and gearbox | 1635 | - | - | |||||
| Overall dimensions, mm | See fig. 7 and 8 | |||||||
ADJUSTMENT YAMZ ENGINES-7511.10, NMЗ-7512.10, IMZ-7513.10, YaMZ-7601.10
BELTS TENSION ADJUSTMENT
The drive of the water pump, compressor and generator is carried out by V-belts, on the reliable operation of which the normal operation of these units depends. Therefore, in the daily care of engines, protect the belts from oil and fuel, control their tension and adjust it. Especially carefully check the tension of the belts during the first 50 hours of engine operation, since at this time they are most stretched. The tension of the belts must always be normal, since both excessive and insufficient tension leads to premature failure. In addition, excessive tension on the water pump drive belt can cause damage to the pump bearings.
A normally tensioned water pump belt, when pressed on the middle of a long branch with a force of 40 N (4 kgf), bends by 10 ... 15 mm (Fig. 44), and the compressor belt bends by 4 ... 8 mm on a short branch (Fig. 45). Check the tension of the generator drive belts by pressing with a force of 40 N (4 kgf) on the middle of the branch of each belt (Fig. 46), while the generator drive belts must bend by 10 ... 15 mm. If the belts bend more or less than specified, adjust their tension.
Adjust the tension of the water pump belt (Fig. 44) with a tensioner, for which:
loosen the bolts of the tensioner bracket lever;
using a Ø12 mm knob inserted into the hole in the tensioner bracket lever, tension the belt;
without loosening the tension force, tighten the bolts of the tensioner bracket lever;
check belt tension.
Rice. 44. Checking the tension of the water pump belt
Rice. 45. Checking the tension of the compressor belt
Rice. 46. Checking the alternator belt tension
Adjust the tension of the compressor belt with a tensioner. Before adjusting, loosen the lock nut one turn, the tensioner pulley axle nut half a turn, and the tensioner bolt nut two turns.
Rotate the tensioner bolt to adjust the belt tension. After adjustment, tighten the axle nut and locknut to 120…150 N m (12…15 kgf m) and the tensioner bolt nut
on the head of the right row of cylinders, the rocker arms of the exhaust valves to the end of the axle, the intake valves - to the thrust washer;
on the head of the left row of cylinders rocker arms of the exhaust valves to the thrust washer, inlet valves
- to the end of the axle.
The exhaust valves of the right bank of cylinders are located closer to the fan, the left row of cylinders - to the flywheel.
Adjustment sequence:
Rice. 48. Cranking the crankshaft
Rice. 49. Valve clearance adjustment
To adjust the gaps, unscrew the nut of the adjusting screw, insert the probe into the gap and, turning the screw with a screwdriver (Fig. 49), set the gap to 0.25 ... 0.30 mm. While holding the screw with a screwdriver, tighten the nut and check the clearance. With properly adjusted
gap, a probe 0.25 mm thick should enter with light pressure, 0.30 mm thick - with force.
To adjust the valve clearances of the remaining cylinders, turn the crankshaft in the same direction until the intake valve of the regulated cylinder is completely closed and an additional 1/3 turn. Adjust gaps as indicated above (see item 6).
After adjusting the clearances, start the engine and listen to its operation. Knocks in the valve mechanism should not be. If there is a characteristic knock of the valves, stop the engine and repeat the gap adjustment.
Install and secure the cylinder head covers, check the condition of the gaskets. Oil should not leak at the place where the covers fit.
CHECKING AND ADJUSTING FUEL INJECTION ADVANCE ANGLE YAMZ ENGINES-7511.10, NMЗ-7512.10, IMZ-7513.10, YaMZ-7601.10
To adjust the fuel injection advance angle, two hatches are provided on the flywheel housing (see Fig. 50), and the angle values \u200b\u200bare marked on the flywheel in two places. For the lower pointer 3, these values are made on the flywheel in numerical terms, and for the side pointer 4, in letter terms, while the letter "A" corresponds to a numerical value of 20 °; the letter "B" -15 °; the letter "B" -10 °; the letter "G" -5 °.
Rotate the engine crankshaft clockwise (when viewed from the fan side) until the marks on the crankshaft pulley and the distribution gear cover or on the flywheel with the pointer, corresponding to the fuel injection advance setting angle - 6º ... 7º, are aligned. In this case, the valves in the 1st cylinder must be closed.
Rice. 50. Alignment of the marks on the flywheel with the indicators of the flywheel housing:
1 – flywheel housing; 2-flywheel; 3, 4 - pointers of the flywheel housing; 5–top hatch plug; A - direction of rotation of the crankshaft
You can rotate the crankshaft with a key for the crankshaft pulley bolt or with a crowbar for the holes in the flywheel (Fig. 48) with the flywheel housing manhole cover removed.
At the moment of combining the labels, the label must be aligned
"A" at the end of the coupling (Fig. 50, 51) with the risk "B" on the index. If the marks do not line up, you need to make adjustments.
The procedure for adjusting the injection advance angle (Fig. 51):
without knocking down the combined position of the marks, tighten the bolt of the terminal connection to a torque of 16 ... 18 kgf m. In this case, the deviation of the plate package from the position in one plane should be within ±1 mm. The measurement should be made near the places where the plates are fastened. In the event of the appearance of corrugations on the plates 4, they are eliminated by alternately loosening and subsequent tightening with a torque of 11 ... 12.5 kgf m of four bolts 5 fastening the plates to the coupling half flange and to the damper coupling;
..
torque of 10 ... 20 N m (1 ... 2 kgf m), with a larger tightening torque, the adjustment will be violated due to the movement of the pulley axis.
Adjust the alternator drive belt tension by moving the alternator relative to the axis of its attachment. Before adjusting, loosen the generator fastening bolts, the generator bracket fastening nuts and the generator fastening bolt to the bracket. After adjustment, securely fasten the generator. With increased exhaust and a break in at least one of the alternator drive belts, replace both belts with a set to ensure a uniform load on them.
CYLINDER HEAD TIGHTENING YAMZ ENGINES-7511.10, NMЗ-7512.10, IMZ-7513.10, YaMZ-7601.10
Rice. 47. The procedure for tightening the cylinder head nuts:
a) - a common head for four cylinders; b) - a common head for three cylinders; c) - an individual cylinder head.
Check the tightening torque of the cylinder head nuts with a torque wrench in a cold state of the engine and, if necessary, tighten them up to a torque of 235 ... 255 N. m (24…26 kgf . m).
Tighten the nuts in the sequence shown in fig. 47 in ascending order of numbers.
ATTENTION ! IT IS STRICTLY FORBIDDEN TO TIGHTEN THE NUTS TO A TORQUE GREATER THAN SPECIFIED, AS THIS WILL RESULT IN BROKEN STUDS AND BROKEN THE CYLINDER HEADS, AND THIS WILL NOT RESTORE THE TIGHTNESS OF THE CONNECTION.
ATTENTION ! WHEN INSTALLING THE CYLINDER HEAD TO THE ENGINE OR LOOKING SIGNIFICANTLY, TIGHTEN THE NUTS IN AT LEAST THREE TIMES (SEE SECTION "REPAIR")
After tightening the cylinder head nuts, adjust the thermal clearances in the valve mechanism and install the cylinder head covers.
ADJUSTING CLEARANCES IN THE VALVE MECHANISM YAMZ ENGINES-7511.10, NMЗ-7512.10, IMZ-7513.10, YaMZ-7601.10
Thermal gaps in the valve mechanism are designed to ensure a hermetic fit of the valve on the seat when the parts of the valve drive expand during engine operation. The value of the thermal gap at the intake and exhaust valves is set the same and is adjustable within 0.25 ... 0.30 mm. When re-checking the gaps after scrolling the crankshaft of the adjusted engine, it is possible to change them to the limits of 0.20 ... 0.35 mm due to an error in the shape and location of the surfaces of the parts of the gas distribution mechanism, which is acceptable.
If the thermal gaps are too large, the valve lift decreases, as a result of which filling and cleaning of the cylinders deteriorate, shock loads increase and wear of the gas distribution mechanism parts increases. At very small gaps, as a result of thermal expansion of the parts of the gas distribution mechanism,
tight fit of valves to the seats, gas-dynamic processes in the engine cylinders are disturbed, the power and technical and economic indicators of the engine are deteriorating. In addition, reducing the clearance in the exhaust valve drive can lead to overheating of the valves and their burnout.
Adjust thermal gaps on a cold engine or not earlier than 1 hour after it has stopped.
When adjusting the thermal clearances and re-checking them, it is recommended to press the rocker arms of the valves:
loosen bolt 2 of the terminal connection: flange 3 - drive coupling half 1;
by turning the damper coupling, align the indicated marks;
Rice. 51. High pressure fuel pump drive coupling:
1-leading coupling half; 2–bolt terminal connection; 3 – coupling half flange; 4–drive plates; 5–bolts of fastening of plates of a drive; 6 washers; 7–damper clutch; 8 - pointer; 9 – high pressure fuel pump; A-mark on the damper coupling; B-mark on the pointer
