Hi Guys. First post. 2003 Jetta 2.0 engine. 175 miles. Owned car for 6 months. First couple months no issues. Then overheated (gauge all the way to red). Gas station mechanic changed a couple hoses and the thermostat/housing. Said the PO must have used a stop-leak additive. Found some gunk in the system. Car didn’t overheat for two months, then started to again.
Symptoms: can idle in park for 30-40 minutes then start to overheat. Driving, will overheat within 5 miles, to the red or near to it. Both fans come on high when the needle gets beyond one mark right of 190. Both fans come on low (when not overheating) when I turn the AC on. I have heat and AC in the cabin. The only thing that lowers the temp back to normal is putting it in park, reviving to 3k, in which case the needle goes to normal within minutes, then returns to the red upon driving just as quick.
I’ve changed the thermostat (and tested it) and the blades of the water pump were in tack. I’ve also seen water being pushed through the upper radiator hose. I’ve changed the radiator heat switch and the fan control module (I took it to the dealer and they said those parts were defective). I’m running it with VW coolant. None of this has made a difference. Also, there’s no oil in coolant, water in oil and there’s no white smoke coming from engine. The car runs great and appears to have been well cared for by the PO.