Let's consider the assembly of a diesel engine in a certain sequence, given that our parts and assemblies were previously assembled and tested

For assembly, you will need special mandrels and fixtures that can be made according to the dimensions indicated in the drawings.

Cylinder block subassembly

We install the cylinder block on the stand (see figure), fixing it with fixing pins for the four holes of the block.

When reassembling the cylinder block, the dowel pins are pressed under the cylinder heads, the distribution gear cover and the flywheel housing are installed.

We press the pins with a mandrel, which ensures that they protrude above the mating surfaces of the cylinder block by no more than 10 mm.

We clean the oil channels of the block with bristly ruffs and a cotton napkin, using a ramrod for this purpose.

The plugs of the horizontal and vertical oil channels must be screwed in with nitro putty or thick nitro paint.

Drift for pressing the front bushing of the pushrod axle into the cylinder block

We press the front bushing of the pusher axle into the hole of the block in such a way as to ensure that the hole in the bushing coincides with the oil supply channel in the cylinder block.

The sleeve is pressed in with a mandrel (Fig. 1), which provides a size of 7.5 mm from the front end of the cylinder block to the front end of the sleeve.

Dress for pressing the injection pump drive shaft oil seal into the cylinder block

To press in the oil seal of the driven gear shaft of the high pressure fuel pump drive:

  • - the gland is installed on the mandrel (Fig. 2);
  • - lubricate the outer surface with diesel oil and press it into the bore of the cylinder block, maintaining a size of 69 mm from the front end of the cylinder block to the end of the stuffing box (provided with a mandrel).

Installation of injection pump drive and tappets

Safety mandrel when installing the driven gear shaft assembly injection pump drive to the cylinder block

The injection pump drive is installed in the bore in the upper part of the cylinder block from the front end.

To protect the stuffing box from damage, we put on a safety mandrel on the free end of the shaft (Fig. 3).

Dress for pressing the shaft assembly of the injection pump drive into the cylinder block

When installing the drive, a mandrel is used (Fig. 4) and after installation, the outer rings of the ball bearings must rest against the ledges of the cylinder block seats.

After aligning the hole of the thrust flange for fastening the drives with the holes of the cylinder block, screw in the bolts with the lock washers on and bend their edges on the verge of the bolt heads, pressing them tightly against the edges.

After tightening the bolts, the fuel pump drive shaft should rotate easily, without jamming.

Then we turn the block 180˚ - position with the crankcase up and install the pushers.

Pushers are mounted on the axle with a gap of 0.012 mm.

Missing the clearance will cause the engine to run abnormally.

With a larger gap, the pushers warp and knock, and with a small gap, they seize.

Pushers installation sequence

Location of gears of YaMZ-236/238 diesel drives

Install the extreme axle of the pushers assembly into the front bushing with the plugged end outward, move the axle inside the cylinder block.

We install sequentially the pushers of the first and fourth cylinders for the YaMZ-236 engine (the first and fifth cylinders for the YaMZ-238 engine) and the spacer.

Install the rest of the bushings of the pusher axles and the other two pushers on the extreme axle.

In the sleeve of the third support of the cylinder block, we install the middle axis of the pushers, install the pushers, spacer sleeve and pushers in series.

At the same time, we install pushers for two cylinders on one axle according to the cylinder numbering: for YaMZ-238 engines - 2-6, 3-7, 4-8 and for YaMZ-236 engines -2-5, 3-6.

The pushers are installed in such a way that the heel of the pusher is turned towards the window in the cylinder block under the pusher bar.

The tappets should turn easily on the axles, without sticking, and the axial displacement should be limited toporous bushings. All parts must be wiped and lubricated with diesel oil before installation.

Camshaft and crankshaft installation

We install the camshaft in the cylinder block assembly with gears, having previously checked the location of the pushers.

The repair dimensions of the camshaft bearing journals must correspond to the repair dimensions of the holes of the bushings pressed into the cylinder block.

Before setting the sheikh of the camshaft, we liberally lubricate with diesel oil and combine the installation mark "P" (see Fig. 5) on the tooth of the drive gear 5 of the fuel pump drive with the mark "P" on the length of the tooth of the driven gear 7 of the injection pump drive.

When aligning the holes of the thrust flange with the holes in the cylinder block, it is necessary to put the flange so that it blocks the hole, under the axis of the pushers in the cylinder block.

We screw two bolts with lock washers into the aligned holes. The antennae of the lock washers should enter the holes of the thrust flange, and the ends of the washers, after tightening the bolts, are bent and pressed against the edges.

After the final tightening of the bolts, the camshaft should rotate easily, without jamming.

The circumferential clearance in the meshing of the gears should be within 0.09 - 0.22 mm; we check the gap at three equally spaced points, with the engine block positioned with the crankcase down.

Install the engine crankshaft. For a detailed technology for installing the crankshaft, see the article "Installing the crankshaft on the engine".

Installing the timing gear cover, fan drive, front engine mount bracket and crankshaft pulley.

Before installing the distribution gear cover, the mating plane is wiped, lubricated with sealant and the right and left cover gaskets are installed.

When installing gaskets, wrinkles, tears and overlapping of connecting channels with gaskets are not allowed.

Dress to prevent oil seal damage when installing timing gear cover

To protect the crankshaft oil seal in the cover from damage, we put on a safety mandrel (Fig. 6) on the front end of the crankshaft and lubricate the oil seal with diesel oil.

We install the cover of the distribution gears on the pins of the cylinder block, having previously wiped the mating surfaces, and fasten it with ten bolts with flat and spring washers.

We install the fan drive on the studs of the cover of the distribution gears, having previously installed the gasket. In this case, the fan drive gear must engage with the camshaft gear.

We fix the fan drive with four nuts with washers.

We install the upper cover of the cylinder block on the studs and fasten it with two bolts and five nuts with flat and spring washers.

Before installing the cover, wipe the mating surface and install a gasket on the studs. When attaching the cover, do not completely tighten the bolt and nut under the generator bracket.

Then we install the hatch plug gasket and the plug itself on the top cover of the gasket, which we fasten with four bolts with spring washers.

Crankshaft pulley press tool

We install the bracket for the front engine mount on the cover of the distribution gears and fasten it with four bolts with spring washers.

The bolts must be tightened to a torque of 90-110 Nm (9-11 kgcm). Before installing the front support, it is necessary to wipe the mating surfaces.

When installing the crankshaft pulley, it is necessary to turn the crankshaft to the position for pressing the segment key and press it into the keyway of the front end of the crankshaft.

Then we wipe the seating surfaces and press the pulley onto the front end of the crankshaft until it stops against the collar and fasten it with a bolt with a washer.

When pressing the pulley onto the front end of the crankshaft, we use a pneumatic tool (Fig. 7).

To do this, a pulley is installed on the pipe 3, we screw the rod 1 with the handle 12 into the crankshaft hole under the pulley mounting bolt.

Combine the groove in the pulley with the key on the front end of the crankshaft and supply air to cylinder 10 by opening valve 9.

When the piston moves along with the pipe Z and sleeve 4, the pulley is pressed in.

For the convenience of work, we hang the device on the balancer by the earring 8.

The air pressure in the system must be maintained within 0.5–0.6 MPa (5–6 kgf/cm2).

Installing the flywheel housing, flywheel and ventilation tfelling.

To install the flywheel housing, it is necessary to turn the cylinder block 90 ° with the rear end up, wipe and lubricate the mating surface of the cylinder block under the flywheel housing with sealant.

Dress to prevent oil seal damage when installing flywheel housing

Then install the flywheel housing gasket on the dowel pins on the cylinder block and the safety mandrel (fig. 8) on the rear end of the crankshaft.

The surface of the mandrel and the sealing lip of the stuffing box must be lubricated with diesel oil.

We install the flywheel housing on the locating pins of the cylinder block and fasten it with bolts with spring washers, which we tighten with a torque of 80-100 Nm (8-10 kgf m).

Installation sketch and bending of flywheel lock plates

We install the flywheel on the crankshaft locating pins using a suspension.

We tighten the flywheel bolts with a torque of 200-220 Nm (20-22 kgf m) and lock them with locking plates installed under the head of each pair of bolts, and bend them on the edges of the bolts, as shown in Figure 9.

To facilitate the installation of the flywheel in the correct position relative to the crankshaft, the numbers 2 are stamped on the flywheel hub and on the end of the shaft, which must be aligned during assembly.

We fasten the ventilation tube to the cylinder block with two bolts with enclosed engraving washers.

To do this, insert bolts with washers into the holes of the ventilation tube, put a gasket on the bolts and install it on the cylinder block, screwing the bolts 1 - 2 threads by hand, then install the clamp on the ventilation tube and fix it with a bolt to the flywheel housing.

After that, we finally tighten the ventilation pipe mounting bolts.

Installation of CMO filters and injection pump

When installing centrifugal and coarse oil filters, the surfaces of the cylinder block must be wiped, lubricated with sealant and gaskets applied.

We install the high-pressure fuel pump on the platforms located between the cambers of the cylinders and turn the crankshaft into position to press the key into the driven gear shaft of the fuel pump.

To protect the shaft, we install a stand under it and press the key with a mandrel.

Then we install the half-coupling assembly on the driven gear shaft of the high-pressure fuel pump drive. Before setting, it is necessary to check the alignment of the marks marked with the “O” sign on the flange and coupling half.

The high-pressure fuel pump assembly with the speed controller and the automatic injection advance clutch is installed on the block and fastened with four bolts, having previously put washers on them.

We connect the automatic injection advance clutch of the high-pressure fuel pump to the half-coupling of the driven gear shaft using a textolite washer.

In this case, it is necessary to ensure the axial clearance between one cam of the leading half-coupling and the end of the automatic injection advance clutch within 0.5 - 0.6 mm, and the gap between the second cam and the end of the clutch is at least 0.5 mm.

We check the gaps with a set of feelers.

In addition, it is necessary to ensure the coincidence of the marks on the drive half-coupling and the automatic injection advance clutch, we fix the nut of the half-coupling of the driven gear shaft and cotter it.

We will consider the continuation of the diesel assembly in the following articles, which will be considered:

  • - assembly technology of the cylinder-piston group;
  • - oil pump installation;
  • - installation of cylinder heads, rocker arms and adjustment of valve clearances;
  • - installation of injectors, fuel lines and connecting pipe;
  • - run-in and test of the engine;
  • - cold engine break-in;
  • - hot engine break-in.