Cooling system airbound? Temperature control not working? Low coolant? Water pump not circulating coolant?
If your radiator isnt leaking and car is having a over heating problem and coolant spewing out. Chances are your thermostat needs replaced. possible the radiator needs to be flushed. But more likley its thermostat
First thing you should check is the antifreeze level. If that is fine, replace the thermostat. If it still over heats after the thermostat, then most likely you need to replace the waterpump. If your antifreeze is low, check for leaks, the radiator, hoses, heater core, and water pump. If the water pump is leaking, that is your problem, replace that and thermostat all in one.
Your radiator may not be heating up properly due to issues such as air trapped in the system, a malfunctioning thermostat, low water levels, or a faulty water pump. It is important to have a professional inspect and diagnose the problem to ensure proper heating in your radiator.
I was having the same problem with my car. When you take the thermostat out it will automatically read cool. But I later found out that I had a leak in my radiator and had to replace it. Turned out that my heads are warped and was leaking oil into my water and into the radiator itself. Once i replaced the radiator its been fine.
If you have an old ISUZU Trooper, the radiator thermostat may be not working. Therefore, it will not let cool water from the radiator into the hot engine, even if the radiator is full. Have the thermostat checked and replaced, if necessary. Good Luck
Leaking hose? Defective thermostat housing or bad thermostat gasket? Bad water pump or gasket? Leak in radiator? Leak at heater core? Leak at head gasket? Coolant recovery tank?
1. Water pump possibly weak, failing or leaking coolant 2. Thermostat is not operating correctly or the housing for it is leaking coolant. 3. The water jacket in the engine block has possible restrictions or leaks somewhere. Head gasket breach...leaking coolant? Freeze plugs on side of block? 4. The radiator hoses (upper or lower) have issues and are leaking. What area of the engine compartment is the STEAMING COOLANT coming from? Top, Bottom, Front, Back, Radiator, Engine etc. (This info is important for anyone to be able to help diagnose the problem without being able to ACTUALLY see it).
I would check the hoses leading into your radiator, and also the overflow for antifreeze. If that is not the problem, it could be your heater core. Your heater core might be leaking, you might have a hose leaking
Where is it leaking? That pressure test sounds funny, why would you pressurize only the pump and radiator? If you are leaking coolant outside the engine, locate the source. If you are losing it from the radiator but cannot find a puddle suspect a head gasket problem. Check the Radiator cap first, if it is bad high pressure coolant will travel back to the overflow bottle.
The top radiator hose is above the thermostat. If the top radiator hose is hot, the thermostat is opening. The thermostat is not the problem. Perhaps the radiator is clogged up or the water pump is bad. Look elsewhere.
You need to have it tested by a knowledgeable mechanic. They use some kind of blue liquid that should stay blue during the test. If it turns yellow, you have a problem. If your car is running hot and nothing else has solved the problem (thermostat, radiator flushed, leaking radiator, hose or pump..., you should have it checked.
It could be the thermostat. Open up the radiator cap when it is hot and see if the water is flowing in the radiator. If it is not then it may be a thermostat.