We remove the camshafts for replacement as well as when repairing cylinder head elements.
To remove the camshafts, you will need tools: keys for 8, 10, 13, 16, socket heads for 10, 16, 18, 17, Torx E14, keys Torx T8, Torx T14, a bronze drift, an engine support, a clamp for installing a TDC, a camshaft lock, as well as an additional three containers for flushing diesel fuel with a capacity of approximately 2 liters each, a piece of hardened wire with a diameter of 0.5 mm and a length of approximately 10 cm.
We prepare the car for work. We install it on a lift or a viewing ditch.
We remove the timing belt (see the article How to replace the timing belt Nissan Almera).
We remove the oil separator of the ventilation system (article - Cleaning the ventilation system of the K4M engine crankcase)
With a 10 head, unscrew the bolt securing the arm of the probe guide tube to the air intake bracket
We remove the tube with the dipstick from the socket of the engine sump.
The tube is sealed with a rubber ring.
With a head of 8, unscrew the two eye bolts
Remove the eyelet with the bracket
With a head of 8, we unscrew the twenty-four bolts securing the cylinder head cover
Use a screwdriver to pry off the cylinder head cover (for the tides on the cover, placing a rag).
We take out two rubber-metal plugs from the cylinder head
Remove the exhaust camshaft
Remove the intake camshaft
We inspect the camshafts for wear and defects
The surfaces of the bearing journals "B" and cams "A" must be well polished and not damaged.
On the working surfaces of the journals, scuffs, nicks, scratches, aluminum enveloping from the bearing seats in the block head are not allowed.
If traces of galling, overheating, deep notches or wear in the form of a cut are found on the working surfaces of the cams, as well as uniform wear over 0.5 mm, the shaft must be replaced.
Thoroughly clean the oil supply channels from deposits.
Do not grind the camshaft cams to eliminate stepped wear, since the valve timing will be violated when the cam profile is resized.
Checking the radial runout.
If the runout is more than 0.02 mm, the shaft must be replaced, since it is not allowed to edit it.
Install the shafts in reverse order.
When installing new shafts, it is recommended to install new valve levers.
To check the hydraulic mounts, remove the lever
We take out the hydraulic lifter from the cylinder head socket
Checking hydraulic lifters is discussed below.
To remove the pulley, lay the camshaft. We put a box wrench 18 on the pulley nut.
Insert the screwdriver through the hole in the pulley.
Leaning on the hub of the pulley with a screwdriver blade, press the key with the screwdriver shaft and turn it counterclockwise.
In this case, the pulley should not rotate, and the nut will loosen.
Remove the pulley from the toe of the camshaft
Remove the oil seal. We also remove the oil seal from the other camshaft.
We apply sealant to the mating surface of the cover.
We install the cylinder head cover and tighten the bolts of its fastening to the moment in the sequence indicated in the table.
С 1 по 12
С 14 по 19
21 и 24
Having installed the cylinder head cover, with a tool head or a piece of pipe of a suitable size, we press new camshaft oil seals into the cylinder head sockets, after applying a thin layer of engine oil to the working edges of the oil seals.
The installation of oil seals is described in the article - "Replacing the oil seals of the camshafts of the K4M engine"
Numbering of the cylinder head cover mounting bolts
After checking the phases of the valve timing and fixing the shafts, we install the toothed pulleys on the toes of the camshafts so that the Renault emblems, printed on the spokes of the pulleys, are vertically up (exhaust valve shaft) and down (intake valve shaft).
Having hooked on the nuts for securing the pulleys, we slightly tighten them.
We install on the pulleys and tighten the timing belt.
Tighten the camshaft pulley nuts with a tightening torque of 30 Nm and turn them by 84˚.
We turn the crankshaft clockwise two turns and check the correctness of the valve timing.
If necessary, we repeat the installation of the valve timing.
Checking and flushing the hydraulic valve lifters
Hydraulic clearance compensators in the valve drive mechanism are used to compensate for thermal expansion of the drive elements.
The operation of the hydraulic compensator is based on the principle of incompressibility of engine oil, which constantly fills the internal cavity of the hydraulic compensator during engine operation and moves its plunger when a gap appears in the valve drive, ensuring constant contact of the roller of the pressure lever of the valve drive with the camshaft cam without a gap.
This eliminates the need for valve adjustments during maintenance.
Hydraulic lifters are non-separable compact devices inserted into the sockets of the cylinder head.
Valve knocking when the engine is running can be caused by:
- air ingress into the over-plunger cavities of the hydraulic lifters when the oil level in the crankcase is too low or too high, as well as when the car is parked for a long time on a slope;
- contamination of the precision surfaces of the hydraulic clearance compensators in the valve drive mechanism with sludge from low quality engine oil (or if it is untimely replaced, as well as if the oil filter is damaged);
- wear of hydraulic lifters.
If it is not possible to restore the operation of the hydraulic lifters by pumping or flushing, replace them, since their design is non-separable.
First, make sure that the extraneous noise during engine operation is caused by a malfunction of the hydraulic lifters:
- start the engine.
In the event of a malfunction of the hydraulic lifters, extraneous noise in the area of the block head cover appears immediately after starting the engine and changes in accordance with the change in the engine crankshaft speed.
If the noise does not appear immediately after starting the engine or does not change when the crankshaft speed changes, the malfunction is not caused by a malfunction of the hydraulic lifters.
Moreover, if the noise does not change when the crankshaft speed changes, it is likely that the cause of the extraneous noise is not in the engine;
- when the engine is idling, make sure that the noise level does not change when the load changes (for example, when switching the automatic transmission selector from position N to position D when disengaging the clutch of a car with a manual transmission or when turning on the electrical consumers and the air conditioner).
If the noise level changes, the cause may be the collision of parts due to wear of the liners of the connecting rod and main bearings of the crankshaft, and not a malfunction of the hydraulic lifters;
- warm up the engine to operating temperature. If the noise has decreased or disappeared, it is possible that the knock of the hydraulic lifters is caused by oil contamination. In this case, it is necessary to flush the hydraulic lifters:
- if the noise has not disappeared, it is likely that air has entered the hydraulic lifters, and it should be removed.
If the oil level in the crankcase is too low, the oil pump traps air together with the oil; If the oil level in the crankcase is too high, the oil is agitated and foamed by the crankshaft counterweights.
When the car is parked for a long time on a slope, oil flows out of the cavities of the hydraulic lifters and oil channels, and the supply of oil to the hydraulic lifters after starting the engine requires some time, during which the cavity of the hydraulic lifter has time to get air.
In all these cases, when oil with air enters the supra-plunger cavity of the hydraulic compensator, the air inside the cavity when the valve is opened will be compressed and the hydraulic compensator will be under pressure, which will lead to a characteristic knock of the valve mechanism with increased clearances.
To remove air from hydraulic lifters, do the following:
check the oil level in the engine crankcase and, if necessary, bring to normal;
- start the engine and warm it up at idle speed for 1-3 minutes;
- increase the crankshaft speed to 3000 rpm, then sharply decrease it to idle speed and let the engine idle;
- repeat the cycle and check if the noise of the valve drive mechanism has disappeared.
If the hydraulic lifters are in good working order, the noise disappears after 10-30 cycles;
- after the disappearance of the noise, repeat to remove air five more times;
- Let the engine idle for 1-3 minutes and make sure that the noise of the valve drive mechanism has disappeared.
If the noise of the valve drive mechanism does not disappear after bleeding and warming up the engine to operating temperature, identify the faulty hydraulic lifters as follows.
Stop the engine and immediately after stopping, set the piston of the 1st cylinder to the TDC position of the compression stroke, remove the cylinder head cover.
Remove the camshafts.
To check the performance of the engine hydraulic lifters, press on the rocker arm resting on the hydraulic lifter. If the rocker arm can be moved with little or no effort, the hydraulic lifter is faulty.
Similarly, check the condition of the hydraulic lifters of the remaining cylinders (the order of operation of cylinders 1-3-4-2).
After identifying faulty hydraulic lifters, you must first try to flush them as follows:
Remove the rocker arms.
Remove the faulty hydraulic lifter from the cylinder head socket.
Prepare three identical containers with a capacity of about 2 liters for flushing the hydraulic lifters.
The dimensions of each container must be sufficient so that the hydraulic compensator, lowered to the bottom of the container in an upright position, is completely immersed in the liquid.
Fill containers with clean diesel fuel.
Place the hydraulic lifter in the first container and clean the outside of it.
Having immersed the hydraulic compensator in the first container halfway, with the plunger down, gently pressing the wire through the hole, squeeze the valve ball and, keeping the ball squeezed out, move the hydraulic compensator plunger 5-10 times until the plunger movement becomes completely free.
If you cannot achieve easy movement of the plunger, replace the hydraulic lifter.
Remove the hydraulic lifter from the container and, pressing the valve ball, move the plunger until diesel fuel is completely drained from the hydraulic lifter.
Place the hydraulic compensator in the second container and repeat step 5.
Remove the hydraulic lifter from the container and drain the diesel fuel from it as described in step 6.
Place the hydraulic compensator on the bottom of the third container vertically, with the plunger up and squeeze the ball of its valve with a wire.
Keeping the valve ball depressed, move the plunger down and then slowly move up to fill the lifter lift with diesel fuel.
Remove the hydraulic lifter from the container; holding it with the plunger up, press down on the plunger with slight force and make sure that it remains stationary.
Check the total height of the hydraulic lifter at the same time by comparing it with a new hydraulic lifter.
If during the check it was possible to move the hydraulic lifter plunger, repeat steps 9 and 10 until the cavity of the hydraulic lifter is completely filled with diesel fuel.
If after that the hydraulic lifter does not reach the working condition or its total height is less than the height of the new hydraulic lifter, replace it.
Before assembling the valve drive mechanism, store the filled hydraulic lifters only in a vertical position with the plungers up. Avoid getting dirt into hydraulic lifters.
Install hydraulic lifters on the engine as soon as possible after refueling to avoid possible loss of diesel fuel.
Install hydraulic lifters and all removed parts in the reverse order of removal.
Start the engine and let it idle for 1-3 minutes. If necessary, bleed the hydraulic lifters as described above.