Valve Clearance bad rattle in the tappets

The valve tappet clearance for the Mazda Bongo Brawny can vary depending on the specific engine model and year. Here are some general specifications for the different engine types: 2.0L FE engine: Intake valve clearance - 0.18-0.22mm, Exhaust valve clearance - 0.28-0.32mm 2.5L WL engine: Intake valve clearance - 0.20-0.25mm, Exhaust valve clearance - 0.30-0.35mm 2.5L RF engine: Intake valve clearance - 0.20-0.25mm, Exhaust valve clearance - 0.30-0.35mm It's important to note that the valve tappet clearance should be checked and adjusted by a qualified mechanic using the correct specifications and tools. Incorrect adjustment can cause engine damage and poor performance.

note Perform the valve clearance check and adjustment at the engine cold state. 1.Remove all of the ignition coils. 2.Remove the cylinder head cover.
caution Turn the crankshaft always clockwise. 3.Turn the crankshaft clockwise, and align the timing mark on the exhaust camshaft sprocket against the upper face of the cylinder head as shown in Figure. Therefore, No.1 cylinder goes to the compression top dead center. 4.Using a thickness gauge, measure the valve clearance with the arrow shown in Figure. If deviated from the standard value, make note for the valve clearance.
Standard value:

Intake valve 0.20 ± 0.03 mm (0.008 ± 0.0012 inch)
Exhaust valve 0.30 ± 0.03 mm (0.012 ± 0.0012 inch)

5.Turn the crankshaft clockwise 360 degrees, and put the timing mark on the exhaust camshaft sprocket in position shown in Figure. Therefore, No. 4 cylinder goes to the compression top dead center. 6.Check the valve clearance with the arrow shown in Figure. In the same procedure as 4.
7.If the valve clearance is deviated from the standard value, remove the camshaft and the valve tappet. For the camshaft removal, refer to Camshaft Removal and Installation . 8.Using a micrometer, measure the thickness of the removed valve tappet. 9.Calculate the thickness of the newly installed valve tappet through the following equation.
A: thickness of newly installed valve tappet
B: thickness of removed valve tappet
C: measured valve clearance
Equation

Intake valve: A = B + [C - 0.20 mm (0.008 inch)]
Exhaust valve: A = B + [C - 0.30 mm (0.012 inch)] note The valve tappet ranges 3,000 - 3,690 mm (0.1181 - 0.1453 inch) and has 47 types per 0.015 mm (0.0006 inch). The thickness below a decimal point is stamped on the reverse side of the valve tappet. 10.Install the valve tappet selected through the procedure 9, and put the camshaft in position. For the camshaft installation, refer to Camshaft Removal and Installation .
11.After installing the timing chain, measure the valve clearance using the procedure 3 to 6. Confirm the clearance is within the standard value.
caution Completely remove all the old FIPG, which might be remaining among the components. 12.After completely removing the liquid gasket adhering on the timing chain case, cylinder block and cylinder head, degrease them with white gasoline.
caution The cylinder head cover should be installed within 3 minutes of applying liquid gasket.

13.Apply a 4 mm bead of liquid gasket as illustrated.
Specified sealant:

THREE BOND 1217G or equivalent

14. Install the cylinder head cover and tighten the tightening bolts using the following procedures.
(1) Temporarily tighten to the following torque in order shown in the illustration.
Tightening torque: 3.0 ± 1.0 N·m (27 ± 8 in-lb)(2) Tighten to the specified torque in order shown in the illustration.
Specified torque: 5.5 ± 0.5 N·m (49 ± 4 in-lb)15.Install the ignition coils.

Unless the is a modified engine, there is no setting on the valve clearance. It has hydraulic valve lifters and they don't require any setting of the valve tappets.If they are making noise when it is running the you have a bad valve lifter. Unless you can get some kind of lubricant to add to the oil that will clean the lifters, you may have to install new ones.

Valve Clearance Valve clearance is there to allow the valves to cool in between combustion events (spark), and to make sure the valve closes properly and contains the combustion explosion. You need to cool the valves a little bit, the exhaust valve moreso than the inlet, as it's what sees the most heat as spent burnt gases go past it into the exhaust port. Run too little clearance and you'll cause the valve to "weld" a little bit to its' seat every time it closes, and then take seat metal off again when it opens. Do this enough times and you burn out the valve seat and need the head reconditioned. However, by running less clearance, the valve stays open for that little but longer, and you get more air in and out of the motor, and make more power. Run too much clearance and your motor just sounds like a diesel and loses power and tappet rattle annoys you while you're driving, so it's better to err on the side of caution.
The stock valve clearance (0.008" inlet / 0.012" exhaust, warm) is pretty good for any of the cams I've listed above, they're well-sized street cams, not really wild top heavy race cams that require super high compression to work, so don't be afraid to close the valves up a bit from the suggestions of the cam grinder, which will usually say between 0.010" and 0.014". There are a few ways to set your valve clearances:
Yellow Book Method This is from the factory 3K/4K/5K engine manual, aka The Yellow Books. It's the quick and lazy method.
Set engine to #1 TDC. Crank pulley timing mark should be on 0, distributor rotor should be pointing towards spark plug 1 or 2. Set tappets (counting from the front) 1, 2, 3 and 5. Rotate engine 360 degrees, crank pulley to 0 again, distributor rotor turned 180 degrees. Set tappets 4, 6, 7 and 8.
Nine Method I've never really gotten into doing this, takes too much time and maths for my liking :P Rotate the engine through its' range of movement, as one valve is "on the rock" of its' max lift, subtract the valve number from 9 and that's the tappet you should be setting. For example, if #8 valve is open, set clearance on valve #1. If valve #7 is open, set clearance on #2. And so on.
Stewart uses this method, and rotates the camshaft through its entire base circle and sets the clearance at the highest point. Which is a pretty good idea, as it compensates for the possibility that the base circle has been ground unevenly, and allows you to run the proper valve clearance that you want to run, instead of something that may be a few thou larger in reality.

Sometimes a dirty oil filter will cause lack of oil to the top end at startup.
As soon as the oil warms, it flows better and faster and hence the noise goes away after warm up.

If you need valves adjusted, the motor must be at TDC on compression stroke(both valves closed)
The motor must be cold do not try to adjust the valve clearance on a warm engine.

On TDC, pull the valve covers and check the clearance on the intake and exhaust valves by inserting a feeler gauge under the tappet.
INTAKE should be : .03-05mm
EXHAUST should be .05-.08 mm

Im sure you don't need a valve adjustment. but if you do: Put Engine on TDC
Loosen the locknut with a 9 or 10 mm wrench, stick the feeler gauge under the tappet, and tighten the little square tipped valve adjuster screw clockwise until you feel friction on the feeler guage.
Enough friction that the feeler gauge feels tight but you can still slide it back and forth.
Not carefully tighten the locknut. Check the feeler guage during tightening to make sure it didn't get too tight or too loose. Once you set the clearance, move to the next valve, and repeat the process using the other feeler guage.
Once both are done put the covers back on and your done,

NOTE: You may have to remove seat, gas tank, airbox, and side covers to get to the covers.

your valve tappet clearance is too big. What you need to do is just to adjust the valve tappet clearance. It is a tedious job and require some basic skill to do it, if you are not sure, leave it to the service centre to do it.

When setting tappets, it has to be born inind that the valve stem wears an indentation into the face of the rocker. This prevents a really accurate tappet adjustment, so the customer is right again. If you do not posess a tappet setting dial gauge, a normal engineers dial gauge will do just as well. The procedure is the same as using your feeler gauge except that you set the dial gauge up on the cylinder head with the pointer resting on the head of the rocker. Press down fairly firmly on the rocker valve end and zero the gauge. Next lift up on the rocker and read off the clearance, from the gauge, Use a magnetic base to support your gauge and repeat the pocedure for each valve pair.

0.10 - 0.15mm inlet
0.18 - 0.23mm exhaust
but you must be carefull because the top of the valve seat becomes concave from wear, a feeler guage will not give the most accurate reading, hope i have been of some hel

On the intake 0.0008 or 0.0020 (it's in between these 2)

this is for the stem to guide clearance. (for the intake)

The Exhaust 0.0018 to 0.0030 stem to guide clearance.

This is not a forum for automotive data. But "tappet clearance" is a UK term, only. Try search for "valve clearance" and "Hilux 2400 cc" or Hilux 2400cc"