Getting too hot!

[Reasty]

Im having a big problem with the mk3 8v at the moment,the car was running cold (below 70) so changed the thermostat and now the car is running at 110 which is too hot,have checked everything and im sure theres no air in the system,thought it might be the eurocarparts stat i put in,so have now put a genuine vag one in and still the car runs at 110 degrees.all pipes are hot and heaters are hot but the rad and the bottom pipe are cold,i have flushed the whole system 3 times now but still no change,do you think i need a new radiator as i cant understand if theres hot water going in which there defiantly is then why is the rad cold and why is the bottom pipe cold,to add to the wierdness even tho the radiators not getting hot, at just past 110 degrees the fan comes as its supposed to,this really is doing my head in now so any ideas anyone? my suspision is that the rad is knackered?? 

[Christo77]

I'm still guessing it's air in the system, although the waterpump may come into the picture..
When you had the hoses off did you run some water through the rad just to see you had flow through?  it also flushes out the remains of old coolant..if you've got flow and it's not leaking then your rad should be ok..
Also on refil did it take enough coolant to reach it's capacity? should be about 6.3 litres.. if not then that's a clue..

[VWstevo]

Im having a big problem with the mk3 8v at the moment,the car was running cold (below 70) so changed the thermostat and now the car is running at 110 which is too hot,have checked everything and im sure theres no air in the system,thought it might be the eurocarparts stat i put in,so have now put a genuine vag one in and still the car runs at 110 degrees.all pipes are hot and heaters are hot but the rad and the bottom pipe are cold,i have flushed the whole system 3 times now but still no change,do you think i need a new radiator as i cant understand if theres hot water going in which there defiantly is then why is the rad cold and why is the bottom pipe cold,to add to the wierdness even tho the radiators not getting hot, at just past 110 degrees the fan comes as its supposed to,this really is doing my head in now so any ideas anyone? my suspision is that the rad is knackered?? 

Hi Mate

Sounds like air to me mate. I had the same problem. I had to drain the system again and once i filled it back up i drove around for 10 minutes and it was fine. Steve

[Reasty]

I'm still guessing it's air in the system, although the waterpump may come into the picture..
When you had the hoses off did you run some water through the rad just to see you had flow through?  it also flushes out the remains of old coolant..if you've got flow and it's not leaking then your rad should be ok..
Also on refil did it take enough coolant to reach it's capacity? should be about 6.3 litres.. if not then that's a clue..

Yeh took both hoses off the rad and put a hose pipe into the top and the water was gushing out the bottom of the rad was brown but then ran clear

[Reasty]

Just realised my header tank cap is black,could it be that the cap is therfore faulty and venting to early thus no letting the system gain pressure to push the water round?

[AudiA8Quattro]

Try bleeding the system first, this can cause all sorts of problems.
Run the car with the cap off with the heater set to hot, fast idle the car while a mate watches the water level, when it starts to rise in the expansion tank put the cap back on.
If need be let the system settle for a couple of hours, then repeat.

[tianaroja]

I have just done exactly the same thing today  , it must be the day for changing themostats!, thermostat had jammed open so  heater stopped working , i have changed the themostat but now the car is running at over halfway on the guage  i have squeezed all the hoses topped up run the car for 10 mins and it is still the same. [previuosly the temp was stable at just about 70 now it stable but over half way. i did notice the themostat i took out had a small bypass hole on the flange the new one didnt not sure haw this will affect things  but i woould imagine this helps prevent air locks

[Christo77]

There you go then..i doubt if yourself and Reasty both have either waterpump or rad problems.. most likely still air in the system and it's easy just to fill it up and go.. takes quite a bit of care to do it right..
If i remember i think i filled my radiator first through the top hose, then pushed the other end back onto the engine just a bit..that way i could slowly' fill from the expansion tank allowing air to escape as necessary from the part connected hose..when coolant appeared from there i connected it up fully..also a confirmation was that i got the specified amount of coolant in..If there's air in the system you should have some coolant over..that is if you measured it out etc..
Some chaps here might have other tips but it worked for me..

See how you go..

[Reasty]

Well I got somewhere with it today after stealing my sisters blue xpansion cap and two more hours of squeezing pipes I've got the car to run at 100 instead of 110 so it can bloody stay like that now stupid mk3! I hate the crappy thing anyway and I'm sure it plays up on purpose coz my mk2 gets all the attention.   

[Wayne]

Well I got somewhere with it today after stealing my sisters blue xpansion cap and two more hours of squeezing pipes I've got the car to run at 100 instead of 110 so it can bloody stay like that now stupid mk3! I hate the crappy thing anyway and I'm sure it plays up on purpose coz my mk2 gets all the attention.   

That still seems hot.