The camshaft is replaced in the following cases: – the pressure in the engine lubrication system has dropped
The cause of this malfunction is often increased wear of the camshaft journals and seats in the camshaft bearing housing.
In this case, the camshaft is replaced simultaneously with the bearing housing; – valve knocking with serviceable hydraulic bearings of the drive levers.
Caused by increased wear of the camshaft cams due to the use of low-quality engine oil or damage to the oil filter.
In this case, the bearing surfaces of the valve drive levers are usually damaged, which in this case must be replaced at the same time as the camshaft.
You will need: keys "10", "13", "17", "24".
Remove the camshaft bearing housing together with the shaft (see "Replacing the hydraulic valve lifters of the Niva Chevrolet").
Disassemble the camshaft bearing housing, for which unscrew the two bolts securing the camshaft thrust flange.
Remove the thrust flange from the groove in the front support journal of the shaft.
Remove the camshaft from the bearing housing by sliding it forward.
When removing the camshaft from the bearing housing, be careful – do not damage the bearing surfaces of the camshaft journals with sharp edges of the cams.
Inspect the camshaft.
No nicks, dents, scratches, or aluminum drag from the bearing housing are allowed on the working surfaces of the journals.
Wear on the working surfaces of the cams is not allowed to exceed 0.5 mm, as well as scoring and wear of the cams in the form of faceting.
Replace the shaft with detected defects.
Measure diameters of the shaft bearing journals.
They should be (counting from the front):
- 1 – 45.915–45.931 mm;
- 2 – 45.615–45.631 mm;
- 3 – 45.315–45.331 mm;
- 4 – 45.015–45.031 mm;
- 5 – 43.415–43.431 mm.
Inspect the camshaft bearing housing.
Cracks on the housing are not allowed.
No marks, scratches, burrs, or excessive wear are allowed on the working surfaces of the journal bearings.
Measure the inner diameters of the camshaft housing bearings.
They should be (counting from the front):
- 1 – 46.000–46.025 mm;
- 2 – 45.700–45.725 mm;
- 3 – 45.400–45.425 mm;
- 4 – 45.100–45.125 mm;
- 5 – 43.500–43.525 mm.
If the clearances between the journals (see step 7) and the bearings exceed 0.2 mm (wear limit), replace the housing and, if necessary, the camshaft.
Install the new camshaft and bearing housing, as well as all removed units and parts, in the reverse order of removal.
Before installing the camshaft in the bearing housing, lubricate the working surfaces of the journals and cams of the camshaft with engine oil.
Tighten the bearing housing mounting nuts in the order shown in the figure (see "Replacing the hydraulic valve lifters of the Niva Chevrolet").