My old 1990 Subaru (190 000km) starts overheating after 15 min of driving
The engine was rebuilt about 4 weeks ago. We replaced head gaskets, timing belt incl. the tensioner, water pump, thermostat and radiator. In the beginning the car ran greatly, no overheating even under severe driving conditions. No leakage of coolant could be observed. But a couple of days ago the engine overheated quickly just during normal driving. In the beginning I assumed the overheating was because of the air pockets, I bled the cooling system a couple of times but the overheating problem was still there. The pressure in the cooling system seemed to be very high as I noticed yesterday that the upper radiator hose was leaking. I tightened the clamp today an that leakage stopped, but the car was still overheating.
I live on the hill, so I needed to get back home. The engine overheating gauge was showing 90% as arrived. I checked the engine after arrival. No vapor was coming out, and there was coolant coming out of the overflow system (the radiator cap is alright). But I also found there was something else leaking, it was in the area of water pump. That area was not leaking yesterday. I don't think that was the cause of the problem, as it was not leaking as the overheating started a couple of days ago and I assume that this leakage occurred due to the very high pressure in the cooling system.
The interesting thing is I can't here the water flow through the system inside when I turn on the engine (I used to hear that sound before). The heater in the cabin is working, however it only starts to heat after about 5 min of driving.
I have no clue what it could be. Can anybody help me with this? I'm desperate. It took us huge effort to replace the head gaskets etc, and now a similar problem arises.