I got a 1990 Toyota hilux with a 22r engine in it. i changed the head and the head gasket it had coffee coloured stuff in the radiator but the coolant & the coffee coloured stuff weren't sticking

OVERHAUL MANUAL.
Toyota Hilux Pick UP S-LN106 single cab long body
no year told. 1997>?
no country told (for parts and manuals VALID)
no engine told
the line up world wide engines this truck
WHAT?
Petrol:
1.6 L 1Y I4
2.0 L 3Y I4
2.2 L 4Y I4
2.4 L 22R I4
2.4 L 22R-E I4
2.4 L 22R-TE turbocharged I4
3.0 L 3VZ-E V6
Diesel:
2.2 L L I4
2.4 L 2L I4
2.4 L 2L-T turbocharged I4
2.5 L 2KD-FTV (China)

bleed any air out by loosening off the highest hose ( heater hose )
run with the heater open (on) to move any air out of the heater core
normally not problem with toyota but worth the check first

it could be a head gasket or cracked head
have a compression test done to determine the problem

Sounds like a warped head take to a mechanic have a compression test done. DO NOT USE ANY GASKET SEALER

If your not overheating or losing coolant, its more than likely engine oil burning. If it is coolant related, possible blown head gasket.

NEED TO REPLACE HEAD GASKET IF YOU SEE OIL IN THE COOLANT SYSTEM BAR HEAD WILL STOP UP RADIATOR AND HEATER CORE CAUSE YOU MORE PROBLEMS.

This is usually a sign of a bad head gasket. coolant is entering the cylinder(s) and is being burnt off as steam. coolant is also mixing with the engine oil. The color of the engine oil would be that of coffee with lots of cream if the head gasket is blown. The radiator would also be low on coolant.

assuming fan is working, check for blown head gasket. Remove radiator cap, make sure it's full, start engine, allow to warm up. Once thermostat is open, check for bubbles coming up in the radiator. Combustion products coming into the radiator indicate blown head gasket. If this is not it or you have more questions, please get back to me.

it could be the ff.
1. radiator is clogged
2. no coolant
3. cooling fan is not working fine
4. thermostat valve is stuck up
5. water pump is damaged
6. radiator cap is broken
7. coolant is leaking somewhere
8. the worst is broken cylinder head gasket but broken head gasket always leaves a trace like water is draining w/o a drip or oil is mixing up with your coolant inside reservoir. try eliminating the easy things before deciding to have the cylinder head removed.

First, DO NOT DRIVE YOUR VEHICLE OR RUN THE ENGINE AS LONG AS YOU HAVE THIS CONDITION!!! (exception:can be run 1-2 minutes... for short intervals while testing only). If you run/drive, you can cause severe damage to engine bearings.
1. If residue in radiator appears as semi-thick (like milk shake) light coffee colour, It indicates engine oil in cooling system. Major cause is a blown head gasket or cracked cylinder head. This condition usually is accompanied by an overly high oil level on dipstick and wet residue on inside of oil fill cap that is similar to what was found in radiator.
Testing includes pressure test of cooling system. Other symptoms are white smoke from exhaust pipe or coolant on one or more spark plugs (depending on severity or location of failure).
2. If residue is reddish in colour, it indicates a failure of transmission cooler coil within radiator. There is no safe test for this other than identification of contaminant and radiator replacement, including complete trans flush. This condition is far less common than head gasket problems.
3. There are two other coolant entry points to consider depending upon which engine you have: Coolant on any V8 or V6 engine can enter crankcase through intake manifold seals. Some engines use an intermediate housing between the water pump and engine which have passageways for coolant. Gasket failure can allow coolant entry into the engine at this point. (This is also rare but can happen if any bracket bolt that passes through the water pump and intermediate housing has been left loose during or after an alternator, or other accessory repair)
4. If no leak is found, if you just bought vehicle, find out if headgasket has just been changed It is possible that either residue from previous failure was not flushed from system, some type of block sealer was put into cooling system or if gasket was changed, perhaps condition was not corrected and still exists.(ie: gasket replaced but head was cracked or warped and not replaced).
In any case, this should not be ignored or dismissed!!!
Good luck!!!

timing cover is warn through I bet the guides are broken and it makes a knocking sound! most common problem. You will need a timing kit and a cover.