Before starting work, pay attention to the following recommendations:
When replacing rocker arms, it is desirable to replace the camshaft.
Mark all rocker arms before disassembly.
When replacing, only rocker arms designed for engines of this series can be installed.
Before dismantling the cylinder head, do the following:
- Unscrew temperature and other sensors.
- Remove the rocker arms by turning the camshaft so that the nose of the corresponding cam is vertically up.
Pic. 20. Section of the cylinder head. The valve clearance is measured between the camshaft lobe and the rocker arm.
1 - threaded support,
2 - adjusting bolt,
3 - pusher.
Using a puller, press the corresponding valves with springs down and pull out from the side of the rocker arm (see fig. 21).
Pic. 21. Removing levers using a valve puller.
Remove spark plugs.
Unscrew all other parts from the cylinder head. A puller is required to remove the valves. When using it, the valves are removed before the camshaft is removed, as shown in fig. 22. Valve cotters are removed with tongs.
In the absence of a valve puller, the cylinder head is positioned so that there is a stop under each valve to prevent valve movement. Then, on the valve disc, put a pipe section of a smaller diameter than the outer diameter of the valve disc, and by hitting the pipe with a hammer, release the crackers from the groove on the valve stem, the crackers will be in the pipe. Remove the pipe and collect crackers.
Pic. 22. Removing the valve springs with a valve puller.
Remove the spring plate and valve springs. Mark inner and outer springs. Do not use springs with other color marks.
Using a puller or pliers, remove the oil seals.
Remove the valve from the guide bushings and put cardboard tags with the serial number on the valve. On fig. 23. details of the valve mechanism are shown.
Pic. 23. Valve mechanism.
1 - pusher,
2 - crackers,
3 - a plate of springs,
4 - outer spring,
5 - internal spring,
6 - valve turning mechanism,
7 - oil deflector cap,
8 - adjusting ring,
9 - inlet valve guide,
10 - exhaust valve guide,
11 - intake valve,
12 - exhaust valve,
13 - rocker.
Unscrew all camshaft bearing supports and remove the shaft.
The camshafts have five bearing journals. The oil for lubricating the bearings and camshaft cams is supplied through a 10 mm channel from the rear bearing support.