Car overheating 626 1989 EFI 2.2lt aircon, electric windows, power steering radiator just repaired thermostat new When the car is started it pumps heaps of water out of the overflow pipe, then the car at idle, overheats rapidly. gets hot and the engine stalls as help would be appreciated Kind regards Gary

It would have been useful to know where the hose from the tee goes and what diameter as that is new to me. 50 years as a repairer and I have never seen a top radiator hose with a tee branch.

Usually the engine heats and the thermostat opens and starts coolant circulating through the radiator, up the bottom hose into the water pump to be pushed round again.
The volume of coolant moved by the water pump, even at idle should be far in excess of that circulating through the heater matrix ensuring adequate circulation through the radiator as soon as the thermostat opens.

The top hose must be hot because the thermostat is open so why doesn't the coolant go further and heat either the branch or the rest of the hose and radiator...
Sometimes a pump with a plastic impeller will lose a vane and overheating due to insufficient circulation is likely.

Other things are more common - semi-blocked radiator tubes restricting coolant flow.
Silt build up in the cylinder block causing hot spots in the cylinder walls.
Restricted air flow through the radiator.
Electric coolant fan not working.
Excess combustion gas in the cooling system interfering with thermostat operation.
Degassing system blocked with the same result.

Check your fan, if it is electric fan, make sure it comes on. Check if your radiator is blocked or clogged, Remove it and get it inspected & cleaned by a radiator repair shop

The overheating probably came from the coolant being too low. The coolant in the reservoir won't go back into the radiator if the coolant in the radiator is too low. Until you get it fixed, check and fill up the radiator every time you want to use it. Overheating is very bad for engines and can cause expensive engine repairs.
Where is it leaking, from the engine or the radiator? You didn't say, but wherever it is leaking is the place to start. If at the radiator, and it is not a loose or leaking hose, I would be looking for a new radiator. If it is leaking at the front of the engine and dripping down from there, you could have a bad water pump. This could be an expensive repair at a shop-not the pump itself-they are not too expensive-but the labor cost in replacing a water pump will add up.

The thermostat would not cause it to leak. But when all is said and done, you will want a new thermostat, after the leak is fixed. They are very cheap and it is just good insurance.

the power steering pump would have nothing to do with the engine overheating but the water pump certainly would, but before you go to the trouble of replacing the water pump you need to be certain that is the problem as there are other issues that can cause overheating, like the thermostat or a blocked radiator, the mechanic who said it was the power steering pump quiet obviously don't know too much about engines............hope this helps......cheers.

Full coolant level does not mean your engine cannot overheat. You need to fix the problem as overheating will destroy the engine if not addressed.

The radiator cooling fans must be working, as must the water pump. The thermostat must also be working properly.
There must also be no air in the cooling system as air locks will impair water flow. When cooling systems are drained fully or partially and re-filled air in the system must be bled out using the correct bleeding procedure for the particular engine/cooling system. Failure to do this properly will lead to overheating.

If you ONLY see the overheating warning when running your aircon you need to check that the electric radaitor fans are kicking in at idle when you switch on and run the aircon and the engine has been warmed up some. If they do not start operating when the a/c is running you will get an overheating condition in normal driving conditions.

If the radiator fans are operating normally and you still get an overheating warning when the aircon is on or off the most likely culprit is a faulty thermostat in the engine's cooling system which will need to be replaced.

If you have either a faulty thermostat or if the water pump in the cooling system fails you will get continuous overheating whether the aircon is on or off.

1. check if your water pump is is working.
2. check if it is not overheating when the A/C is off. if it is no longer overheating, have your a/c compressor checked by an aircon technician

You need to check youe water pump, thermostat and your radiator cap and if all of that is good it sounds like a blown headgasket.

Are you losing coolant. If you are I would check your heater core which is located under the glove compartment.

Did you burp the coolant? If not, you have air bubbles in the system that are trapped behind the thermostat, keeping it from opening. Run the car at idle until it's 3/4 of the way to overheating, then shut it down and let it cool. Pop the radiator cap and the air bubbles will burp out. Check the level of coolant in the radiator and expansion tank, top off as needed, and repeat a couple times, and you should be good to go.

The thermostat is bolted into the bottom of the water pump, the lower radiator hose connects to a cover that holds the thermostat to the water pump.

the thermostat can be difficult to get at because the AC and power steering pump are all bolted on top of the water pump,

Your problem may not be a bad thermostat.
I would also check:

1) water pump, some of the vw pumps are poorly made & tend to go bad.

2) fans belts, it can be tricky to get the right tension on these belts due to a badly designed tensioner system on the power steering & water pump belt.

3) hoses, radiator, coolant tank,. the radiators and coolant tank tend to leak when they get old, the plastic cracks or the rubber seals go bad.
Also check the electrical system controlling the engine cooling fans. there are sensors and relays that can go bad.
I have owned 8 vw's most of the major problems with these cars was due to electical problems.

4) Engine problems such as a blown head gaskets, or ignition timing problems can cause overheating. luckily VW engines usually don't have these problems, unlike other companies 4 cylinder engines (the Dodge Neons for example)