Installation of the piston-cylinder group

Before installation, the liners must be selected according to the cylinders and the shoulder protrusion should be checked

We select the sleeve without rubber rings so that it snaps into place with a slight pressure of the hand.

The lower end of the liner must fit exactly into the corresponding hole in the cylinder block.

The protrusion of the sleeve collar above the plane of the cylinder block should be within 0.07 - 0.16 mm; it is checked with a fixture (Fig.1).

To check the protrusion of the sleeve shoulder, we install the fixture with the base 7 on the sleeve. In this case, the pin 1, moving up, will turn the lever 2, which will move the indicator leg through the stem 3.

The amount of deviation of the indicator needle from zero reading will give the actual value of the protrusion of the shoulder shoulder.

To install the device, there are two handles 9, which are fastened with four screws 10 to the body 6.

The indicator is installed in the sleeve 5 and fastened with a screw 4.

Tool for liner shoulder protrusion above cylinder block plane

Before using the device, it is necessary to set the indicator so that the arrow is opposite the number 0. The indicator is set on the adjusting ring 8.

We remove the selected sleeve from the block cylinder, clean the seating and sealing surfaces and install rubber sealing rings lubricated with diesel oil into the grooves of the sleeve.

Only rings of the specified size should be used to seal sleeves. They should create a good seal, but should never be worn too tight.

Installing rings that are too tight and with a larger cross-sectional diameter than provided, the liner may be deformed, which will cause the piston to seize.

We install the sleeve assembly with o-rings in the cylinders with a tool (Fig. 2).

To do this, we install hook 4 on the jumper between the windows of the cooling jacket, and mandrel 1 into the sleeve, and through lever 3 and stop 2 we install the sleeve into the cylinders of the block so that the marking of the sleeve class is directed towards the front of the engine (toward the fan) .

When installing the sleeves, make sure that the sealing rings do not twist.

Cylinder Liner Installer

To install the piston group, it is necessary to turn the cylinder block with the flywheel housing down, wipe and lubricate the inner surface of the cylinder liners, turn the crankshaft to a position convenient for assembly, and wipe the first crankpin.

Then, the piston assembly with the connecting rod and rings of the first cylinder, installed in the technological sleeve, is placed with the piston skirt into the sleeve of the first cylinder and pushes the piston into the sleeve.

The piston of the fifth cylinder with a connecting rod and rings as an assembly for the YaMZ-238 engine or the fourth - for the YaMZ-236 engine is installed in the corresponding cylinder.

We install the removed covers on the connecting rod sheikh of the crankshaft, screw in the bolts with lock washers, and tighten them finally with a torque of 160-180 Nm (16-18 kgcm).

Then we check the total clearance between the ends of the lower heads of the connecting rods and the cheeks of the crankshaft (axial play), which should be within 015-0.57 mm.

Measurements are made between the ends of the connecting rods and their caps.

If the gap is less than specified, loosen the bolts and lightly hit the connecting rod cap with a rubber hammer to move it until the required gap is obtained.

After adjustment, we bend the whiskers of the lock washers on the verge of the heads of the connecting rod bolts.

In the same sequence, we install in pairs the remaining pistons with connecting rods and rings assemblies, according to the numbering of the cylinders: for the YaMZ-238 engine: 2-6, 3-7, 5-8 and for the YaMZ-236 engine - 2-5, 3-6.

Installation diagram of pistons on YaMZ-236/238 engine

After installing the connecting rod and piston group, the crankshaft should turn smoothly by hand using a lever with a shoulder of 550 mm without jamming.

When installing the piston group, the following conditions must be observed.

The arrow on the piston head, as well as the lug on the piston pin boss, must point towards the front towards the fan.

The displacement of the chamber in the piston must be directed towards the axis of the engine (Fig. 3).

For the right row of cylinders, pistons with the sign "PR" are installed on the bottom, for the left row of cylinders - with the sign "LV".

Installing oil foot pump and sump

If there are no oil pump mounting studs, we screw them into the crankshaft front bearing cover until it stops with a torque of less than 30 Nm (3 kgm).

Then we install on the gasket block the flange of the outlet pipes of the oil pipeline and the shims of the oil pump housing.

We install the oil pump assembly on the studs and fasten it with two nuts with engraving washers. In this case, a gap in the engagement of the crankshaft gear with the intermediate gear of the oil pump must be ensured within 0.25 - 0.37 mm.

We check the gap with a set of feelers at least at three points.

If the gap is not within tolerance, then it is necessary to loosen the oil pump mounting nuts and install the required number of shims, which should not exceed three pieces, between the pump housing and the crankshaft main bearing cap.

After adjusting the gap, we fix the oil outlet pipes of the oil pump on the cylinder block and the pump housing and the bracket for the suction oil pipe with bolts with lock washers.

When checking the plane of contact between the flanges of the oil outlet pipe 08 and the flange of the suction oil pipe, the probe with a thickness of 0.05 mm should not pass through. The mustache of the lock washers must be bent on the verge of bolts and nuts.

We screw the drain valve of the lubrication system into the cylinder block assembly with the lock washer and tighten it to failure, and then bend the edges of the washer onto the valve body and cylinder block.

To install the pallet on the crankcase, two guide pins must be screwed into the holes for the bolts of the pallet.

A gasket is put on the studs, a pallet and bolts with spring washers are screwed into the aligned holes.

Before placing the pallet, make sure that there are no foreign objects in it and blow it out with compressed air.

We screw two drain plugs with copper gaskets into the pan to failure.

In the next post we will look at:

  • - installation of cylinder heads, rocker arms and adjustment of valve clearances;
  • - installation of injectors, fuel lines;
  • - Run-in and running-in of a diesel engine.