- clean all mating surfaces of the block from gaskets stuck and torn during disassembly;
- fix the cylinder block on the stand, unscrew the oil channel plugs from the front and rear ends and blow all the oil channels with compressed air
Screw plugs into place.
If the clutch housing needs to be replaced or it is installed on the block after repair, it is necessary to first remove two dowel pins from the block, then bolt the crankcase to the block.
A crankshaft is installed in the block on the extreme liners, to the flange of which the indicator stand is attached.
By rotating the crankshaft, check the runout of the hole for the centering shoulder of the gearbox, as well as the perpendicularity of the rear end of the clutch housing relative to the axis of the crankshaft, as shown in the figure.
The runout of the crankcase hole and the end should not exceed 0.3 mm, the end - 015 mm.
If the runout of the hole exceeds the specified value, then the bolts should be loosened and with light blows on the crankcase flange to achieve its correct installation.
After tightening the bolts, the holes for the dowel pins in the crankcase and block are reamed to repair size.
Blackness in the holes is not allowed. After that, pins are pressed into the holes, the diameter of which is 0015-0051 m larger than the hole sizes.
The runout of the crankcase end is eliminated by scraping. It should be borne in mind that during the above check it is necessary to use an unworn crankshaft and liners, which must be removed after replacing the crankcase;
- replace defective cylinder liners with new ones as follows:
- a) using a combined puller, press out the old sleeve.
Having inserted the legs of the puller into the engine cylinder, it is necessary to rest the studs 4 into the block and push the legs apart with the expansion bolt 5. then, turning the screw 7, press the sleeve out of the cylinder;
- b) thoroughly clean the mounting surfaces and sealing surfaces on the sleeve and on the block from scale and corrosion;
- c) insert the repaired sleeve with soft copper gasket into the cylinder from which it was removed.
The sleeve should enter the cylinder freely, effortlessly and protrude above the plane of the block by 002-010 mm.
It is more convenient to first check the amount of liner sinking in the cylinder without a gasket. Drowning should be within 020-025 mm;
- d) fix the sleeve with a holder so that it does not fall out;
- cut off two packings of the crankshaft rear seal (each 120 mm long) from the cord, put them into the block and holder;
- reassemble the crankshaft, to do this, unscrew all the plugs of the dirt traps of the connecting rod journals and remove deposits from them.
Rinse and blow out the oil channels and cavities of the dirt traps with compressed air, tighten the plugs with a torque of 38-42 Nm (38-4.2 kgcm);
- check the condition of the working surfaces of the crankshaft.
Nicks, burrs and other external defects are not allowed;
- press the ball bearing 80203 AC9 with two protective washers into the rear end of the crankshaft. it is allowed to use a 60203A bearing with one protective washer, while 20 g of Litol-24 grease must be placed in the bearing cavity
- Screw the flywheel to the crankshaft. Tighten the nuts to a torque of 76-83 Nm (7.6-8.3 kgcm).
Lock the nuts by bending one of the tabs of the locking plate onto the face of the nut;
- screw the clutch pressure plate assembly with the casing to the flywheel, having previously centered the driven disc using a mandrel (you can use the input shaft of the gearbox) along the hole in the bearing at the rear end of the crankshaft.
The marks stamped on the pressure plate housing and on the flywheel near one of the holes for the housing mounting bolts must be aligned.
Tighten the bolts to a torque of 20-25 Nm (2.0-2.5 kgcm).
- the crankshaft, flywheel and clutch are balanced as an assembly, and therefore, when replacing one of these parts, dynamic balancing should be performed by drilling metal from the flywheel.
Balancing the crankshaft, flywheel and clutch assembly should not be started if the initial imbalance is greater than 200 gsm. In this case, it is necessary to dismantle the assembly and check the balancing of each part separately.
- put on the first main journal of the crankshaft the rear washer of the thrust bearing with an antifriction layer to the cheek of the crankshaft;
- compress the packing of the crankshaft rear seal in the block and holder with a mandrel
- Wipe the main bearing shells and their beds with a clean cloth. Install liners in bed;
- lubricate the main bearing shells and crankshaft journals with clean engine oil and lay the crankshaft in the cylinder block;
- put the caps of the main bearings on the studs of the block so that the fixing protrusions on the upper and lower liners of each cap are on the same side, and the numbers stamped on the caps correspond to the numbers of the beds.
When installing the front main bearing cap, the tab on the rear washer must fit into the groove in the cap.
The end face of the front bearing cap must be in the same plane as the end face of the cylinder block;
- put the caps of the main bearings in their places by lightly tapping with a rubber mallet, the caps should enter the grooves of the beds of the cylinder block;
- put washers on the studs, screw on the nuts, apply 2-3 drops (006 g) of Unigerm-9 sealant on the threaded part of the nuts and evenly tighten the nuts.
The final tightening must be performed with a torque wrench with a torque of 100-110 Nm (10-11 kg/cm).
If there is no sealant, then locking the nuts can be done with a locking plate 24-1005301-01;
- place rubber pads in the grooves of the packing holder and coat their side surface protruding from the groove with soapy water.
Install the holder in place and tighten the nuts;
- turn the crankshaft, which should rotate freely with little effort.
The crankshaft can be rotated by the flywheel or by using a device consisting of the input shaft of the gearbox with a square key welded to it or a handle with a square hole.
The device can also be used for centering when setting the clutch disc;
- put the front washer of the thrust bearing with the anti-friction layer outward so that the pins pressed into the block and the cover fit into the grooves of the washer;
- put on a steel thrust washer of the crankshaft with a chamfer in the inner hole towards the front washer of the thrust bearing;
- press the crankshaft gear to the stop and check its axial clearance.
The check is carried out as follows: put a screwdriver (knob, hammer handle, etc.) between the first shaft crank and the front wall of the block and, using it as a lever, press the shaft to the rear of the engine.
Using a feeler gauge, determine the clearance between the end face of the thrust bearing rear washer and the shoulder plane of the first main journal. The gap should be in the range of 0.125-0.325 mm;
- reassemble the connecting rod and piston group
Clean the piston crowns and piston ring grooves from carbon deposits.
In case of replacement of pistons, sleeves, piston pins or connecting rods, subassembly of mating pairs should be carried out at a temperature of parts (20 ± 3) ° С.
In bored or new sleeves, it is necessary to install pistons of the same size groups as the sleeve. selection from neighboring groups is allowed, while, as in the selection of pistons in working sleeves, the selection is made according to the pulling force of the probe tape with a thickness of 0.05 mm and a width of 10 mm.
The probe tape is placed in a plane perpendicular to the axis of the piston pin along the largest diameter of the piston. The force on the dynamometer connected to the probe tape should be 35-55 N (3.5-5.5 kgf);
- pick up the piston pin to the connecting rod so that it fits snugly into the connecting rod hole under the force of the thumb, moves freely, without jamming and does not fall out under the action of its own weight when the axis of the connecting rod hole is located at an angle of 45 ° (approximately).
Piston pin and connecting rod must be the same or adjacent size group.
The piston pin should be lightly lubricated with engine oil when selecting. Size groups of piston and piston pin must match.
Piston with piston pin, piston rings and connecting rod assembly must be controlled by weight. The difference in mass per engine must not exceed 12 g;
- Press the piston pin into the piston and connecting rod using the tool. At the same time, heat the piston to a temperature of 60-88 ° C, lightly lubricate the piston pin with engine oil.
Connect the piston with the guide mandrel 3 to the connecting rod, put the piston pin on the thin end of the mandrel, as shown in the figure, put the thrust bearing 5 on the pin and screw the pin in place with the screw 6.
Pressing a finger into a cold piston can damage the surface of the holes in the piston bosses, as well as deform the piston itself.
When the piston is placed in the cylinder (according to the “FRONT” mark on the piston), the hole for lubricating the cylinder mirror from the lower head of the connecting rod should be facing the opposite side of the camshaft;
- pick up the piston rings on the cylinder, as shown in the figure.
The gap measured at the joints of the rings should be 03-0.7 mm for the compression rings and 0.3-1.0 mm for the steel disks of the oil scraper ring.
In worn cylinders, the smallest gap is 0.3 mm;
- use a feeler gauge to check the gap between the rings and the wall of the piston groove, as shown in the figure.
Check the circumference of the piston at several points.
The clearance value should be within 0.050–0.870 mm for the upper and lower compression rings, and 0.135–0.335 mm for the assembled oil scraper ring;
- put protective brass tips on the connecting rod bolts, compress the rings by crimping or, using a conical ring, insert the piston into the cylinder, as shown in the figure.
Before installing the piston, you should once again make sure that the numbers stamped on the connecting rod and its cover correspond to the serial number of the cylinder, check the correct position of the piston and connecting rod in the cylinder;
- tighten the connecting rod by the lower head to the connecting rod neck, remove the brass tips from the bolts, put on the connecting rod cover. The connecting rod cover should be installed so that the numbers stamped on the cover and connecting rod face the same direction.
After baiting the nuts, apply 2-3 drops (0.06 g) of Unigerm-9 sealant to the threaded part of the nuts and evenly tighten the nuts.
The final tightening of the nuts must be done with a torque wrench to a torque of 68–75 Nm (6.8–7.5 kg/cm).
In the case of using working parts from nuts and bolts, it is necessary to remove the remnants of the previously applied sealant, degrease them with gasoline and dry them;
- in the same order to insert the piston of the fourth cylinder;
- turn the crankshaft by 180° and insert the pistons of the second and third cylinders;
- turn the crankshaft several times, which should rotate easily with little effort;
- assemble the camshaft in the following order:
• to put on the forward end of a camshaft a spacer ring and a persistent flange;
• press on the camshaft gear with the tool and secure it with a bolt and washer. Tightening torque - 55-60 Nm (5.5-6.0 kg / cm);
• using a feeler gauge inserted between the thrust flange of the camshaft and the gear hub, set the axial clearance
• clean the distribution gear lubrication tube and fasten it to the block with a bolt and collar; camshaft. The gap should be within 0.1-0.2 mm;
- insert the assembled camshaft into the hole of the block, having previously lubricated its bearing journals with engine oil.
When gears are engaged, the crankshaft gear tooth marked "0" must be against the notch at the camshaft gear tooth cavity.
The side clearance in engagement should be in the range of 0.025-0.1 mm.
With a larger or smaller gap, pick up another pair of gears;
- through the holes in the camshaft gear, attach the thrust flange to the block with two bolts with spring washers;
- install the oil deflector on the neck of the front end of the crankshaft with the convex side to the gear;
- check the suitability of the cuff pressed into the cover of the timing gears for further work.
If the oil seal has worn edges or loosely grips the crankshaft pulley hub inserted into the oil seal, replace it with a new one.
It is recommended to press the cuff into the cover using a mandrel, as shown in the figure.
- put on the studs of the gasket the cover of the distribution gears;
- Center the cover on the front end of the crankshaft with a mandrel and tighten all the nuts and bolts of the cover.
If there is no centering mandrel, then the cover can be installed on the hub of the crankshaft pulley.
The hub must be pressed onto the crankshaft so that its end enters to a depth of 5 mm into the hole in the cover.
After that, fix the cover with nuts, maintaining the same clearance around the circumference between the hub and the opening of the cover.
Align the gap with light blows of a wooden or rubber hammer on the cover. After that, finally fix the cover;
- remove the centering mandrel and press on the pulley hub with the crankshaft damper pulley
- insert a rubber plug into the keyway and press in the key;
- Wrap the coupling bolt into the toe of the crankshaft, having previously put a toothed washer on it.
Turning the crankshaft by the coupling bolt, check if the damper pulley touches the timing gear cover; - install the oil pump assembly with the oil receiver;
- install the oil pump drive and the ignition distributor sensor in the following order:
• Turning the crankshaft, align the third mark on the damper disk with the index rib on the cover of the timing gears.
The camshaft cams, which actuate the valves of the first cylinder, must be directed with their peaks in the opposite direction from the pushers (towards the oil sump) and are located symmetrically
• check the axial clearance between the drive housing and the gear using a feeler gauge
• put a gasket on the drive fastening pins; The gap should be in the range of 0.15-0.40 mm;
• turn the drive shaft to the position shown in A and put the drive into the block seat.
When inserting the drive into the socket, it is necessary to slightly rotate the oil pump shaft so that the end of the drive shaft enters the hole in the pump shaft.
The drive must be inserted without significant force.
In a properly installed drive, the slot in the shaft sleeve should be parallel to the motor axis and offset from the motor, as shown in B;
• fix the drive;
- to check up presence of a backlash in gear wheels of a camshaft and a drive;
- lubricate the joints of the lower flange of the cylinder block with the timing gear cover and the packing holder with Elastosil 1Z7-8Z adhesive-sealant or UN-25 paste;
- install the oil crankcase gasket on the lower flange of the cylinder block;
- install the oil sump on the studs and secure it with nuts and washers, evenly tightening the nuts;
- install and bolt the lower part of the clutch housing;
- clean the combustion chambers and channels of the cylinder head from carbon deposits and deposits, wipe and blow with compressed air;
- lap the valves using a lapping paste composed of one part of M-20 micropowder and two parts of I-20A oil.
Before starting lapping, check for warping of the valve disc and burnout of the valve and seat.
In the presence of these defects, it is impossible to restore the tightness of the valve with one lapping, and the seat must first be ground, and the damaged valve replaced with a new one.
If the gap between the valve and the sleeve exceeds 0.25 mm, then the tightness cannot be restored either. In this case, the valve and sleeve must be replaced with new ones.
Valves (in spare parts) are available in standard size, and guide bushings are available with an inner diameter reduced by 0.38 mm (to deploy them to the final size after being pressed into the cylinder head).
The worn guide bushing is pressed out using a mandrel.
Valve seats are removed by milling with a carbide countersink.
Repair seats have an outer diameter of 0.25 mm larger than the standard ones, so the seats for the seats are bored to the following dimensions: for the inlet valve seat - 49.25 + 0.025 mm, for the exhaust valve - 42.25 + 0.025 mm.
Saddles, guide bushings, before assembly, must be cooled in carbon dioxide (dry ice), and the cylinder head heated to a temperature of 160-175 ° C. During assembly, saddles and bushings must be inserted into the sockets of the head freely or with light force.
The new bushings of the inlet and exhaust valves are pressed in until they protrude 20 mm above the head; after pressing, expand the bushing holes to a diameter of 9 + 0.022 mm, and grind the seat chamfers, centering on the hole in the bushing.
When grinding, ensure that the chamfer on the valve seat is concentric with the hole in the sleeve within 0.05 mm. Chamfers are ground at an angle of 45 °.
The outer diameter of the chamfer at the seat for the inlet valve should be 46.8 mm, and at the outlet - 38.8 mm.
The chamfer width should be at the inlet valve seat 1.8 - 2.3 mm., At the exhaust - 2.3-2.5 mm.
The width of the chamfer is obtained by grinding the inlet valve seat at 30° as shown in A, and the exhaust valve at 15° for valve B. The chamfer must be uniform all around.
After grinding the seats and lapping the valves, thoroughly clean all gas channels and blow with compressed air so that no abrasive dust remains;
- coat the valve stems with a thin layer of colloidal Graphite diluted in engine oil, or lubricate with oil
- press valve stem seals onto the valve guide bushings, insert the valves into the bushings according to the marks made and assemble them with the springs. Make sure that the crackers entered the annular groove of the valves;
- rub graphite powder on both sides of the cylinder head gasket and put it on the studs.
Install the head and secure it with nuts and washers. Tighten the nuts with a torque wrench to 83-90 Nm (8.3-9.0 kg/cm) following the order
- clean with a wire and blow out with compressed air the holes in the rocker arms, in the rocker arm axle and adjusting screws, in the fourth main pillar of the rocker arm axle and the oil channels in the cylinder head.
Check the reliability of the fit of the bushings of the rocker arms.
In the event of a loose fit during operation, the bushing may move and block the tappet rod lubrication hole. Such bushings must be replaced;
- to make a subassembly of the axis of the rocker arms.
Before setting each rocker arm, lubricate its bushing with engine oil;
- insert the pushers into the sockets according to the marks on them. Lubricate the tappets and holes in the block with engine oil;
- insert the rod assembly with tips into the holes in the cylinder head;
- install the assembled rocker axle on the studs and secure with nuts and washers. Adjusting bolts with their spherical part should lie on the sphere of the upper tip of the rod;
- set the gaps between the ends of the valve stems and the noses of the rocker arms. The gap between the rocker arms and the first and eighth valves is 0.35-0.40 mm, the gap between the other rocker arms and valves is 0.40-0.45 mm.
- put the gasket and cover of the rocker arms and fix them with bolts with washers, observing the correct tightening, according to the figure.
- lubricate and put on the front cover of the gearbox the clutch release clutch.
- install and secure the gearbox;
- install the clutch release fork;
- install the engine parts and assemblies named in the article "Disassembly of the ZMZ-402 GAZ-2705 engine"