We disassemble the block head for subsequent repair or replacement.

When disassembling, you need to lay out the head parts in order, taking into account their further use.

Removing the cylinder head was discussed in the article - "How to disassemble the ZMZ-402 engine".

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

Using a 13 key, unscrew the nuts securing the thermostat housing

Remove the thermostat housing from the head

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

With a 12 key, unscrew the four bolts of the rear head cover

Remove the rear cylinder head cover.

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

We remove the valves with a puller. This puller has a valve stop.

If there is no such puller, then we put a suitable stop under the valve, you can use a dense rubber washer or a wooden block

The valves must be marked or arranged in order so that they can be put in place during assembly.

We install on the head a special device for compressing the valve springs.

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

Compress the valve spring with a device. If the valve plate wedges, then tap on the stop of the device with a hammer.

Holding the springs compressed, we remove two crackers with tweezers or a thin screwdriver.

Then, gradually weakening the pressure on the handle of the device, we fully unclench the valve springs.

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

We remove the device and remove the valve plate

Removing two springs

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

Using pliers, carefully remove the slinger cap from the guide sleeve.

When removing, we twist the cap a little to make it easier to remove. Caution the sleeve is very fragile!

Remove the support washer.

We turn over the cylinder head.

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

We take out the valve from the block head.

If the wear of the sleeve is large and exceeds 0.25 mm, then pry it off with a screwdriver and remove the retaining ring.

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

Knock out the sleeve with hammer blows through the mandrel.

We cool the new bushing in dry ice or in a freezer, and heat the cylinder head to a temperature of 150-190˚ С, and press the bushing in.

The protrusion of the sleeve above the head must be 20 mm

After the bushings are pressed in, they must be expanded with a special reamer to the required size.

After that, you need to grind the valves to the seats for this:

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

Apply lapping paste to the valve chamfer and install it in the corresponding head sleeve.

We attach a special grinding device to the valve stem.

We press the valve against the seat and turn the valve in both directions.

Разборка и сборка головки блока цилиндров ЗМЗ-402Разборка и сборка головки блока цилиндров ЗМЗ-402

We continue grinding until the valve chamfer along the entire length and width becomes matte and clean.

We wipe the valves from the remainder of the paste

We install new valve seals using a mandrel

We assemble the cylinder head in reverse order.

Assemble the block head in the reverse order of disassembly.

Before installing, lubricate the valve stem seals, valve stems and the rocker arm shaft with engine oil.

Install the valves in accordance with the marks made during disassembly.

Install the thermostat housing gasket and the gasket for the back cover of the block head on Hermesil sealant.

We will consider a more detailed troubleshooting in the article - "Inspection, defect and repair of the cylinder head ZMZ-402".