Can you adjust valve clearance on kia optima 2.0 cdti

A sure sign that it's time for a valve lash adjustment is if your engine is making a loud clicking or tapping noise when starting up or if you experience a loss in engine power. You can find more details on the suggested adjustment frequency here.
https://www.allstatepeterbilt.com/blog/valve-adjustments-explained

How To Check Tappet Clearance

1. Taking all safety precautions.
2. Make sure the piston is on TDC. ...
3. Make sure the engine has cooled down.
4. Loosen the lock nut of the rocker arm.
5. Now adjust the tappet clearance between the rocker arm & valve stem by tightening or loosing the nut below the lock nut.

https://www.marinesite.info/2012/02/1why-tappet-clearances-is-given-and-how.html

To adjust the valve clearances, use a spanner or a socket wrench on the crankshaft-pulley bolt. Turn the engine in its normal direction of rotation until No. 1 piston is at the top dead centre ( TDC ) of the compression stroke .
https://www.howacarworks.com/engine/checking-and-adjusting-valves

intake 0.20mm exaust 0.38mm adjusted with engine cold.

with 1 and 6 fully open - adjust valves 4 [inlet] and 7 [exhaust]

valves 2 and 3 fully open - adjust valves 5 ex and 8 in

valves 4 and 7 fully open - adjust valves 1 ex and 6 in

valves 5 and 8 fully open - adjust valves 2 in and 3 ex

Rotate the engine clockwise only between adjustments

there is no specification for what you want
the valve clearance is between the end of the rocker arm and the end if the valve stem
the stem end is proud of the spring retainer so if your rocker arm is touching the spring retainer , you have a big problem as for the procedure it is set out in the workshop manual but if you don't have a manual it can be done like this
you will need the firing order of the engine first
now adjust no 1 piston valves when the next piston to fire has the valves in the rock position
that is the exhaust valve just closing as the inlet is just opening a bit of movement of the crank makes either valve move up or down
adjust no 1 piston valves
now move on to the next piston to fire and adjust the valves that were rocking
follow that procedure until all the valves are adjusted
for example
on a 4 cylinder engine with a firing order of 1--3--4--2
bring up no 1 piston and adjust the valves when the valves on no 3 piston are rocking
next piston to fire is no 4 so adjust no 2 piston valves
next piston to fire is no 2 so adjust the valves when no 1 valves are rocking
the procedure is the same for engines with any number of cylinders

firing order is 1-2-3
so when no 2 cylinder valves are in the rock position ( exhaust closing at the same time as inlet is opening) that will be no 1 piston tdc compression stroke adjust the both valves to the specification
.006" both valves
when no3 piston has valve rock adjust no 2 cylinder valves
when no 1 has valve rock adjust no 3 cylinder valves
go google and type in valve clearance of deutz 3 cylinder engine
there is another method explained where inlet of one cylinder and exhaust
this is done with one full revolution of the crank
www.deutzamericas.com page 42 of the manual

No, they are hydraulic and self adjusting

- Pull the hand brake and put transmission in neutral.
- Remove spark plug cords.
- Remove the spark plugs.
- Remove the Tappet cover
- Lift up the left front wheel.
Cylinder number 1 is toward the pulleys and belts side.
- Rotate the crankshaft anticlockwise with socket and extension rod and bring the valve tappets (intake and exhaust) No. 4 cylinder on dancing position.
NOTE: THERE ARE OTHER WAYS ALSO TO ADJUST THE FOUR VALVES AT A TIME. BUT AS DIY FOLLOW THE FOLLOWING METHOD TO AVOID ANY CONFUSION.
- Adjust the valve clearance of number 1 cylinder.
Valve clearance:
Intake 0.18 - 0.22 (cold) Exhaust 0.25 - 0.28 (cold)
- Rotate the crankshaft anticlockwise to bring the valves of cylinder 2 on dancing position and adjust the valves of No. 3 cylinder.
- Similarly rotate the crankshaft to bring the valves of No. 1 cylinder on dancing position and adjust the valves of No. 4.
- Rotate the crankshaft anticlockwise to bring the valves of cylinder No. 3 on dancing position and adjust the valve clearance of No. 2 cylinder.

I would like to know how to adjust the valves in engine B20B

no once the timing belt broke the valves no longer move you will need to redo the cam timeing goood luck

Depends on which engine you have. If you have

ADJUSTMENT Although it is sometimes possible to reuse an old cylinder head cover gasket, in most cases it makes more sense to purchase a new one before beginning the procedure. Some vehicles may require the use of silicone sealant either with or without a new cover gasket. For more details, please refer to the cylinder head cover procedures in Engine & Engine Overhaul of this repair guide and refer to the gasket manufacturer's instructions.

Z24i Engine
See Figures 1, 2 and 3
For the intake valves: 1-4-5-8 valve clearance is 0.012 in. (0.30mm). For the exhaust valves: 2-3-6-7 valve clearance is 0.012 in. (0.30mm). The pivot locknut torque specification is 12-16 ft. lbs. (16-22 Nm).

1. The valves must be adjusted with the engine warm, so start the truck and run the engine until the needle on the temperature gauge reaches the middle setting. After the engine is warm, shut it off.
2. Note the location of any wires and hoses which may interfere with cylinder head cover removal, disconnect them and move them to one side. Remove the bolts holding the cylinder head cover in place and remove the cover. Remember, the engine will be hot, so be careful!

Fig. Fig. 1: Check the valve clearance with a flat feeler gauge-Z24i engine

Fig. Fig. 2: Loosen the locknut and turn the adjusting screw to adjust the valve clearance-Z24i engine

Fig. Fig. 3: With the No. 1 piston at TDC, adjust the top set of valves FIRST; with the No. 4 piston at TDC, adjust the bottom set of valves SECOND-Z24i engine

1. Rotate the crankshaft until the timing marks indicate that the No. 1 piston is at TDC of the compression stroke. If you're not sure of which stroke you're on, remove the No. 1 spark plug and hold your thumb over the hole. Pressure will be felt as the piston starts up on the compression stroke.
2. Refer to the accompanying illustration (upper part), then check valves (1), (2), (4) and (6) using a flat bladed feeler gauge. The feeler gauge should pass between the valve stem end and the rocker arm screw with a very slight drag. Insert the feeler gauge straight, not at an angle.
3. If the clearance is not within the specified value, loosen the rocker arm lock nut and turn the rocker arm screw to obtain the proper clearance. After correct clearance is obtained, tighten the locknut.
4. Rotate the crankshaft until the timing marks indicate that the No. 4 piston is at TDC of the compression stroke. If you're not sure of which stroke you're on, remove the No. 4 spark plug and hold your thumb over the hole. Pressure will be felt as the piston starts up on the compression stroke.
5. See the illustration (lower part), then check valves (3), (5), (7) and (8). Check and adjust valve clearance as necessary.
6. Install the cylinder head cover gasket, the cover itself and any wires or hoses which were removed. Check the engine oil level.

KA24E, VG30i and VG30E Engines
See Figures 4 and 5
These models utilize hydraulic valve lifters. Periodic adjustment is neither necessary or possible. There is however a bleed down procedure that is necessary when the valve train has been disassembled.
HYDRAULIC LIFTER BLEED DOWN

1. Remove the cylinder head cover.
2. Check the lifters for proper operation by pushing hard on each lifter with fingertip pressure.
3. If the valve lifter moves more than 0.04 in. (1mm), air may be inside it. Make sure the rocker arm is not on the cam lobe when making this check.
4. Install the cylinder head cover.
5. If there was air in the lifters, bleed the air by running the engine at 1000 rpm for 10 minutes.

Fig. Fig. 4: Cross-sectional view of an installed hydraulic valve lifter-4 cylinder engine

Fig. Fig. 5: Cross-sectional view of an installed hydraulic valve lifter-6 cylinder engine

make sure engine is warmed up. Put cylinder one at top dead center,remove the valve cover,loosen all adjustment lock nuts,adust intake and exhaust valves on cyl #1 and intake valve on #2 and exhaust valve on #3. now rotate crankshaft 360 degrees clockwise, now adjust intake valves on cyl#3 and cyl #4 and exhaust valves on cyl #2 and cyl #4.now tighten lock nuts and install valve cover. specs are intake valves 25mm clearance and exhaust 28mm clearance, use a feeler gauge,heres a picture to show you where to check clearance.