Hi,

I hope you can help me. I have low to moderate amount of heat in my 2002 Audi A4 1.8 T. It starts off hot, then quickly moves to being warm, intermittently getting hotter with higher RPM. In bleeding the coolant system, I've noticed air bubbles present. More importantly, I've also noticed there is 1-2 PSIs of pressure in the cooling system, where there should normally be roughly 18-20 PSI.

I'm trying to figure out why I'm losing pressure and therefore losing heat? There are no noticeable leaks and the coolant reservoir stays at the same level. Also, it doesn't seem to be drawing coolant into the cooling system from the reservoir.

I just recently changed my engine thermostat and the engine temperature stays at 90 after the initial warm up. No overheating.

Appreciate help and ideas!

 

I'd check the heater core first. Heat the car up and see if the hoses to and from the heater core get hot to indicate coolant traveling through them. With the car cool undo the heater core hoses at the engine and try running water through it. If that checks then your heater core is ok and your heat problem is prolly Low water temps related. Usually means thermostat staying open so check the new stat and make sure it's working properly or installed right. The low cooling system pressure readings are prolly from the low water temperature. You need heat to build the pressure up in the cooling system. 90 degree water is cold you need twice that temp+ or more to build your pressure up