Engine overheats and I've changed the water pump already along with the thermostat. What could be the problem?

If you have already checked the radiator, fluids, thermostat, and thermo fans and your 1996 Hyundai Lantra Sportswagon is still overheating, there could be other issues causing the problem. Here are a few other things you can check:

1. Water pump: The water pump is responsible for circulating coolant through the engine and radiator. If the water pump is not functioning properly, it can cause the engine to overheat.
2. Head gasket: The head gasket seals the cylinder head to the engine block. If the head gasket is damaged or fails, it can allow coolant to leak into the engine, which can cause the engine to overheat.
3. Cylinder head: If the cylinder head is cracked or damaged, it can cause the engine to overheat.
4. Engine block: If the engine block is damaged or has a crack, it can cause the engine to overheat.
5. Clogged radiator: If the radiator is clogged with debris, it can prevent the coolant from flowing properly and cause the engine to overheat.

To determine the cause of the overheating problem, it will be necessary to perform a thorough inspection of the engine and related components. If you are unable to locate the source of the problem or are not comfortable attempting to fix it yourself, it is recommended to have the vehicle inspected by a professional mechanic.

Depends on where the coolant is going.
If it is an external leak it could be a leaking water pump. If there are no external leaks and you are loosing coolant, it could be a blown head gasket. Especially if the engine has already overheated once.
A sticking thermostat would cause the engine to overheat and then loose coolant from the overflow tank. But not until it overheats.

Are the cooling fans coming on ? Go under the hood in the engine compartment , with the vehicle running have some one turn on the A/C , do you see and or hear the cooling fans come on ? Could be the coolant temperature gauge is bad ! How many miles on the vehicle ? Ever have water pump replaced ?

1

Check for a loss of system pressure.
Is there a loss of system pressure?
--
Go to Step 2 yes
Go to Step 3 no

2

Inspect and repair any faulty hose connections.
Does the engine still overheat?
--
Go to Step 3 yes
System OK

3

Check for low coolant protection (-37?°C/-34?°F).
Is there low coolant protection (-37?°C/-34?°F)?
--
Go to Step 4 yes
Go to Step 5 no

4

Test solution. Replace the coolant if necessary.
Does the engine still overheat?
--
Go to Step 5 yes
System OK

5

Check the water pump belt for low tension.
Is the water pump belt tension too low?
--
Go to Step 6 yes
Go to Step 7 no

6

Replace the water pump belt tensioner.
Does the engine still overheat?
--
Go to Step 7 yes
System OK

7

Check for an inoperative thermostat bypass.
Is the thermostat bypass inoperative?
--
Go to Step 8 yes
Go to Step 9 no

8

Replace the bypass.
Does the engine still overheat?
--
Go to Step 9 yes
System OK

9

Check the water pump.
Is the water pump inoperative?
--
Go to Step 10 yes
Go to Step 11 no

10

Replace the water pump.
Does the engine still overheat?
--
Go to Step 11 yes
System OK

11

Check the radiator fins for obstruction.
Are the radiator fins obstructed?
--
Go to Step 12 yes
Go to Step 13 no

12

Inspect and clean the radiator fans.
Does the engine still overheat?
--
Go to Step 13 yes
System OK

13

Check the cooling system passage for obstruction.
Is the cooling system passage blocked?
--
Go to Step 14 yes
Go to Step 15 no

14

Inspect and flush the system. Reroute or replace the hose if necessary.
Does the engine still overheat?
--
Go to Step 15 yes
System OK

15

Check the water pump belt for damage.
Is the water pump belt damaged?
--
Go to Step 16 yes
Go to Step 17 no

16

Replace the water pump belt.
Does the engine still overheat?
--
Go to step 17 yes
System OK

17

Check the cooling fans.
Are the cooling fans inoperative?
--
Go to Step 18 yes
Go to Step 19 no

18

1. Inspect the electrical connector. Replace if necessary.
2. Does the engine still overheat?

--
Go to Step 19 yes
System OK

19

Check the throttle body circuit flow.
Is the throttle body circuit flow restricted?
--
Go to Step 20
Go to Step 21

20

1. Inspect the orifice and associated hose. Replace if necessary.
2. Does the engine still overheat?

--
Go to Step 21
System OK

21

Check for a stuck thermostat.
Is the thermostat stuck in the closed position?
--
Go to Step 22
--

22

Replace the thermostat.
Does the engine still overheat?
--
--
System OK

You did not mention the Thermostat which controls the temperature of the engine. Did you mean the Thermostat when you said temp sensor? If not, then change the thermostat.

!st check and make sure the water is flowing in the radiator, then check
the timeing, Mazda will run hot if the timeing is rong.

Most likely you put the thesmostat in upsid down. Good luck

Replace the water pump and thermostat if you already are aware that you have water pump going out.
Thank you for using fixya.com

Are you sure you put the belt back on the right way? Also, did you change out the thermostat?

Where does water come out,if at all?It probably is a water pump since you already changed thermostat.Probably takes 15-20 minutes of good running speed to overheat?Greg

You actually need the thermostat in to pressurize your cooling system or the coolant won't cyle through the radiator, it'll just cycle around the engine. Most people think without the thermostat in the coolant will just pump freely through the engine and radiator, but it doesn't.

Chuck in a new thermostat, purge the air out of the system and see if it overheats then. I gaurentee it won't, if it does then you've got head problems (but they should already be obvious by now).