Camshaft
On the bearing journals of the camshaft, scuffing, nicks, scratches, aluminum enveloping from bearing housings are not allowed. On the working surfaces of the cams, wear of more than 0.5 mm, as well as scuffing and wear of the cams in the form of a cut, are not allowed.
The camshaft is installed with the outer journals on two prisms placed on the calibration plate, and the radial runout of the middle journals is measured with an indicator, which should be no more than 0.04 mm. If the runout exceeds the specified value, then straighten the shaft on the press.
When replacing the camshaft, the valve levers must also be replaced.
Camshaft bearing housing
Rinse and clean before testing (in particular oil passages), and then check the diameters of the holes in the supports and the camshaft journals. If the difference between the diameters of the holes in the supports and the camshaft journals (total clearance) exceeds 0.2 mm (juvenile), body is replaced.
The inner bearing surfaces of the bearing housing must be smooth and free of burrs. If there is damage, the bearing housing is also replaced.
Tensioner
To check tensioner parts (pic. 17) his chains are broken. At the same time, cap nut 1 is screwed from body 2, cracker 9 and spring ring 4 are removed, then plunger 7, spring 5 and rod 3 are removed together with spring 8 and washer 6.
After disassembling the chain tensioner, check whether there are any signs of scoring on the parts, and deep scratches on the mating surfaces of the shoe and the plunger of the chain tensioner. If there is damage, the parts are replaced.
In addition, the elasticity of the spring 8 of the tensioner is checked. Its length in the free state should be 62 mm, under load (12,5±0,6) kgf - 47 mm, and under load (18,5±1,0) kgf - 40 mm.
With less elasticity, the spring is replaced. They also check the young on the shoe and the damper. If there are deep grooves on the rubber surface or the rubber is worn down to a metal base, then the shoe and damper are replaced.
Camshaft drive chain
Before checking, the chain is washed in kerosene, and then the condition of the links is checked. Chips, cracks and other damage are not allowed on the rollers and cheeks of the chain.
When the engine is running, the chain stretches. It is considered operational if the tensioner provides its tension, i.e. if the chain is extended by no more than 4 mm. The chain hood is checked on a fixture with two stepped rollers 1 (pic. 18), on which the chain is put on.
The hood is determined by the distance between the axes of the rollers. But before measuring the distance, chain 2 is stretched with a force equal to 30 kgf, then the force is reduced to 15 kgf, the tension force is again increased to 30 kgf, and then again reduced to 15 kgf and the distance L is measured.
For a new chain, the distance between the axes of the rollers is 485.775+0,5+0,1 mm. If the chain is extended to 490 mm, it is replaced.