Cooling problems

**Jonner123** · 18-10-2019,08:37 PM

Hi was hoping I could find some help or advice. My car seems to not be circulating the coolant properly. The radiator seems to be cold, fans running flat out doesnt get hot on the gauge but you open the coolant cap and it's under alot off pressure. The heaters always blow hot air, currently fitted new cambelt and water pump, head gasket and also the thermostat. it's almost like the thermostat isn't opening it's very strange. Any help or advice is much appreciated. Cheers

**Jonner123** · 19-10-2019,10:26 AM

Hope I posted this in the right place

**Whippy53** · 20-10-2019,02:08 PM

'Anything automotive that isn't VAG related goes here - If "VOLKSWAGEN GROUP" related PLEASE USE THE CORRECT FORUM SECTION!'

**Jonner123** · 20-10-2019,02:12 PM

I dont know how to move it across. My apologies. Could you move it somehow?

**Crasher** · 20-10-2019,06:14 PM

I have assumed your car is a late 8P and not an 8V. If it is an 8V I will move it.

You need to get a fault code read done, you probably have a faulty electric water pump.

**Jonner123** · 20-10-2019,10:21 PM

Hi, thanks for your reply. It is a facelift 8p. No fault codes stored either. I've since had it block tested which has come back fine. No exhaust gases present in the coolant. Can the auxiliary water pump cause overheating issues even if it works without throwing up any fault codes?

**Crasher** · 21-10-2019,11:06 AM

I have found that the gas testing dye kit typically sold by Snap On is not reliable, I have had it not change colour on diesels that definitely have head gasket failure and I think this is due to the construction of modern Multi Layer Steel (MLS) head gaskets. The electric water pump(or pumps as some have one for the heater as well) are very unreliable and TPS depots tend to keep a good stock of both types as the car can have a Pierburg or Buehler and matching bracket fitted. I have never known one to fail on non stop/start without it coming up as a fault code, the only peculiarity I have found is that cars with the heater pump (stop/start cars) can produce a code saying the heater pump is cavitating beacsue the the intercooler pump has failed and not produce a code for the intercooler pump itself but this is a peculiarity of cars with the water cooled intercooler and heater flow support pump. What were are seeing a lot of is failure of the electronically controlled main water pump but you have chnaged that so next I would suggest the thermostat and this is a known fault on DSG cars.

**Jonner123** · 21-10-2019,08:26 PM

Thanks for the info crasher. As it's just the 8p manual it doesn't have that electric water pump the latter cars did. It just had a mechanically driven water pump which was replaced. I've tried 3 thermostats, removed the radiator and checked it's not blocked. As said before I've changed the head gasket and had the head pressure tested etc. That's all fine. After using the die your referring to i stuck it in the exhaust and it did change colour. Before then i was testing with it for over half an hour. So i know what isn't causing the problem i just dont know what is. Expansion tank has also been removed and tested that's all fine. It has the stop start feature but this doesnt work for some reason. I've got a snap on solus pro which has expert mode but no fault codes in any ECU. Any ideas on what else to check regarding this fault? Heater matrix is free flowing too. Cheers