Contents: Disassembly ⇓ Assembly ⇓
Disassembly
Loosen the camshaft toothed pulley mounting bolts, locking each of them in turn with a wrench in the space between the cams of the 1st and 2nd cylinders.
Remove the toothed pulleys.
Remove the camshaft bearing caps by unscrewing their mounting bolts one by one.
Remove the camshafts from the cylinder head supports.
Remove the tappets from the cylinder head holes and place them in order so that they can be put back in their original places during assembly.
Release the valves from the crackers by compressing the valve springs using the Mazda tool 49 0636 100A with the support ring 49 B 012 002.
Remove the springs with plates and put them in order.
Remove the valves.
Remove the valve guide oil seals and spring washers.
Press out the camshaft seals.
Wash and clean the removed parts and the cylinder head.
Check the valve seat chamfers for pitting, corrosion, or damage. Minor damage can be removed by grinding, removing as little metal as possible. After grinding, thoroughly rinse the seats and cylinder head channels and blow them out with compressed air. Remove carbon deposits from the valves. Make sure there is no deformation of the valve stem or cracks in the plate. Check the condition of the valve seat chamfer. In case of minor damage, it can be ground, maintaining the required chamfer angle. Check the clearance between the valve guides and the valve stems.
If the clearance between the guide sleeve and the valve is increased, press out the valve guide sleeve using the Mazda 49B 012 005 punch towards the upper plane of the cylinder head.
The new guide bushing must be pressed in using the Mazda 49 0249 010A punch, ensuring that the guide bushing protrudes above the cylinder head surface within 16.8-17.4 mm.
Check the mating surface of the cylinder head for warpage.
Assembly
Using the Mazda 49 B 012 007 tool, press the valve stem seals onto the valve guide bushings.
Insert the valves into the guide bushings.
Install the thrust washers, valve springs and spring retainers. Compress the springs with the Mazda 49 0636 100A tool with the 49B 012 002 thrust ring and install the valve keepers.
Lubricate the valve lifters with engine oil and insert them into the cylinder head bores, after filling the chambers with engine oil.
Place the camshafts in the cylinder head supports, having previously lubricated their bearing journals and cams with engine oil.
Install the camshaft bearing caps and tighten their mounting bolts to a torque of 1.15-1.45 kgf·m in the order shown in the photo.
Press in new camshaft seals.
Insert the splines of the toothed pulleys into the camshaft sockets.
[Text taken from an online platform: mazbook.ru]
Place the timing pulleys on the camshafts.
Locking the camshafts one by one with a wrench, tighten the toothed pulley mounting bolts.
Turn the camshaft toothed pulleys until the timing marks on the valve timing mechanism are aligned (see photo). When doing this, make sure that the inlet and outlet valves do not touch.