Hi, I hope you can assist me, as I am at my wit's end. My 1.4 tdi polo overheated on the freeway about 2 months ago. No overheating in stop-go traffic. A mechanic serviced it, replaced the water bottle, thermostat and its housing and flushed the system. A week later it overheated again on the freeway. A radiator shop then checked gas emissions, there was no reaction to test liquid. While replacing the radiator they found that the intercooler housing was mounted incorrectly, damaging the intercooler. It was repaired and the car's performance definitely improved. All was well for about 3 weeks, no overheating or even temperature spikes at all. On 24 December I drove further than I usually do, and while raining the car overheated again. I drove very slowly to the nearest garage, as stopping next to the road in my country is not safe and with the rain I would not have been able to see much. Someone helped to brigde the fan so that I can reach my destination, but the car kept on overheating. I stopped and waited for it to cool quite often. When returning home on 26 December, if I kept it below 100km per hour it was ok, but on hills the temp climbed. I am not sure what could still be wrong, and everyone I spoke to were confused as the car has not overheated once in stop-go traffic, only on the freeway. Any advice or ideas of what else to check/test would be greatly appreciated.
My car has 133000 miles.
My car has a manual transmission.
Intermittent overheating problems can be very frustrating. But it sound like you’ve already covered half the bases. Usually overheating problems can be attributed to low coolant, thermostats, or radiators. At other times there may be problems with head gasket leakage which your guys with test liquid were checking for. But VW has thrown in another variable by switching to plastic water pump impellers. The old metal impellers were trouble free, but the plastic impellers can crack and become ineffective. The trouble with the water pump is that you can’t really check it without removing it. So most of the time we eliminate all the other possibilities before looking at that one. But just in case something was overlooked in the other shops, I suggest you contact Your Mechanic to have a technician come to your home or office to check out your overheating problem and let you know what can be done about it.