Newnesie Posted September 5, 2011 Report Share Posted September 5, 2011 (edited) Since I have owned my car i have never heard or seen my engine fan going. It moves freely when pushed but has never come on.Now this weekend on the way to edition all was fine until the last 30 mins where my engine started overheating. I topped it back up when it had cooled down and i made it to edition fine. When waiting to get to our camp my car overheated again.Now I managed to get it the 200 mile journey home with the interior fans on full whack and windows wide open, and I also took my front grill off to improve air flow to the radiator.The fan thing I do not believe is the real issue as I have done many other long journeys with the engine sitting smack bang on 90 degrees. The car has been regularly serviced with oil changed and filter changes.The other things I can think of are temperature sensor gone, and thermostat gone. I will be replacing both of these this week if i can do it, but the guides on here have no pictures any more. (any one got other guides?)I don't think the head has gone as the pipes are all fine and soft.One last thing is I have not changed the coolant since owning the car, could this be a problem at all?Any help or info will be much appreciated, I need to try and get the car fixed this week as I am off to uni next weekend!Thanks, Tom Edited September 5, 2011 by Newnesie Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 5, 2011 Author Report Share Posted September 5, 2011 Anyone?Can anyone let me know if I am right with the following pics please:Thermostat?Temp sensor?Cheers Quote Link to comment Share on other sites More sharing options...
jabbles21 Posted September 5, 2011 Report Share Posted September 5, 2011 Put the part numbers into google or something Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 5, 2011 Author Report Share Posted September 5, 2011 Good shout. Ill go look in a min.Just took it for a drive and it is still misbehaving Quote Link to comment Share on other sites More sharing options...
jabbles21 Posted September 5, 2011 Report Share Posted September 5, 2011 Wont fix itself mate Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 5, 2011 Author Report Share Posted September 5, 2011 Unfotunately, but I did the old, unplug stuff and plug back in technique. Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 5, 2011 Author Report Share Posted September 5, 2011 Couldn't see any part numbers on anything Inside the thing that goes into the rad (which i think is the thermostat) there was this turqouisy stuffIt was also inside when I took the clip off Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 5, 2011 Author Report Share Posted September 5, 2011 I just took the thermostat out and it looked like this The shaft ( im not sure what its called) has popped through the cap it is meant to sit into.I guess that's not what it is meant to be like so i will be ordering a new one.The thermostat looks like this and was so called 'open' when removed, I guess it should be shut, but the engine was a tiny bit warm when doing this and now I cannot get the thermostat to shut. Quote Link to comment Share on other sites More sharing options...
akbarirfan Posted September 6, 2011 Report Share Posted September 6, 2011 Same thing happened to me yesterday mate.The road side service guy has removed the thermostat so that water is flowing round the cooling system full-time (rather than when it reaches 87-90 degrees)This has cured the overheating but it only a temporary fix.Does the whole housing need changing or just the thermostat?Thanks Quote Link to comment Share on other sites More sharing options...
Derv Posted September 6, 2011 Report Share Posted September 6, 2011 The 4 pin green sensor is the G62, which the cluster and ECU use to determine engine temperature.From what I can make out the 3 pin sensor is for the fan control. It looks like you have some bad corrosion there, so you may have a dry joint or some problem there. I would pop the pins out and check them. There is a way of jumping the connections to trigger the fan, but I don't have the current flow diagrams to hand just now.I have never had a bad VAG thermostat that makes the car overheat, and I've done a few. They default to open, making the car run too cool.VAG temperature gauges are pretty inaccurate, and will quite often show 90° when the actual temperature is far from that. VCDS is the best way to check real temperature.It could be that the car is not overheating, but still boiling coolant, due to a leak in the coolant system causing low pressure. This could be as simple as a leaky/loose expansion cap. The boiling point of the coolant raises with pressure.If this is the case the coolant will be unable to to get sufficiently hot to activate the fan, and will boil first.The radiator fan is only designed to provide enough airflow for when the car is stationary or slow moving, it cannot compete with the airflow provided by the car moving at speed through the air. So even if it is overheating when on the move, the problem is not the fan. Being stuck in traffic is a different story.It's good that you have the sense to stick the heater blower on to aid cooling to get you out of bother.If you haven't changed the coolant for a while it could be a good idea to do so. The coolant loses it anti-corrosion properties over time, and can cause problems like water pump spindles corroding, then impellers breaking up.Use only pink VAG G12 or the relevant ++ version.I tend to change mine every 2 years or so. It's not that expensive, unlike the Porsche fill for life stuff.HTH Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 6, 2011 Author Report Share Posted September 6, 2011 The 4 pin green sensor is the G62, which the cluster and ECU use to determine engine temperature.From what I can make out the 3 pin sensor is for the fan control. It looks like you have some bad corrosion there, so you may have a dry joint or some problem there. I would pop the pins out and check them. There is a way of jumping the connections to trigger the fan, but I don't have the current flow diagrams to hand just now.I have never had a bad VAG thermostat that makes the car overheat, and I've done a few. They default to open, making the car run too cool.VAG temperature gauges are pretty inaccurate, and will quite often show 90° when the actual temperature is far from that. VCDS is the best way to check real temperature.It could be that the car is not overheating, but still boiling coolant, due to a leak in the coolant system causing low pressure. This could be as simple as a leaky/loose expansion cap. The boiling point of the coolant raises with pressure.If this is the case the coolant will be unable to to get sufficiently hot to activate the fan, and will boil first.The radiator fan is only designed to provide enough airflow for when the car is stationary or slow moving, it cannot compete with the airflow provided by the car moving at speed through the air. So even if it is overheating when on the move, the problem is not the fan. Being stuck in traffic is a different story.It's good that you have the sense to stick the heater blower on to aid cooling to get you out of bother.If you haven't changed the coolant for a while it could be a good idea to do so. The coolant loses it anti-corrosion properties over time, and can cause problems like water pump spindles corroding, then impellers breaking up.Use only pink VAG G12 or the relevant ++ version.I tend to change mine every 2 years or so. It's not that expensive, unlike the Porsche fill for life stuff.HTHMany thanks for that response it was really helpful. One thing is though that I do not believe there is a leak or little pressure in the system at all as I had measured the coolant levels when at edition and it didnt seem to move when left alone for a day or two.If this new thermostat does not solve the problem then I will take the fan off and see what that corosion is all about, but like you said this shouldnt even be a problem with the over heating. If I cannot work out what is wrong I wil just take it to a garage and get them to fix it. But hopefully, that wont be needed! Quote Link to comment Share on other sites More sharing options...
Derv Posted September 6, 2011 Report Share Posted September 6, 2011 If it was a pressure problem, it would most likely be a problem with the expansion cap, tank or a top bleeder hose, if there is no significant coolant loss, as escaping air could cause the problem.You can tell easily if the system is pressurising if you take the cap off (carefully!) when the engine is warm. Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 7, 2011 Author Report Share Posted September 7, 2011 So what should happen if I take the cap off when the engine is warm?Cheers! Quote Link to comment Share on other sites More sharing options...
Deadmetal Posted September 7, 2011 Report Share Posted September 7, 2011 If its pressurised then the cap should be hard to take off, as the heat should press up.You should be able to hear gases escaping aswell. Sort of like when opening a bottle of coke. Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 7, 2011 Author Report Share Posted September 7, 2011 Okay cool thanks. I think it is because when the engine has been slightly warm and I have been fiddling it has done this. Got my new thermostat today and am about to change it as well as the temp sensor. Only problem is the Haynes manual for Polo does not have pics on changing the temp sensor. Anyone seen any guides on the net anywhere with pics for a lupo/polo engine? Quote Link to comment Share on other sites More sharing options...
georgen Posted September 7, 2011 Report Share Posted September 7, 2011 Do not open cap when up to temp and under pressure, you will get burned and in best case loose a lot of your coolant and make a mess of the engine bay. Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 7, 2011 Author Report Share Posted September 7, 2011 It's cool. I changed the thermostat and temp sensor today and all seems to be hunky dory! (Touch wood)Cheers guys. Quote Link to comment Share on other sites More sharing options...
akbarirfan Posted September 7, 2011 Report Share Posted September 7, 2011 I got told my water pump needs replacing more ££ spent on the Lupo Quote Link to comment Share on other sites More sharing options...
akbarirfan Posted September 9, 2011 Report Share Posted September 9, 2011 Went to Autobarn today for another quote, seems like only the thermostat housing needs replacing Quote Link to comment Share on other sites More sharing options...
Newnesie Posted September 9, 2011 Author Report Share Posted September 9, 2011 Good news!Hope you get yours fixed too Quote Link to comment Share on other sites More sharing options...
akbarirfan Posted September 12, 2011 Report Share Posted September 12, 2011 Just got the thermostat housing changed by Roy at Autobarn (Top guy), all looks good Quote Link to comment Share on other sites More sharing options...
Lev Posted October 31, 2011 Report Share Posted October 31, 2011 Mine has done exactly the same I am just hoping it is only my Thermostat as a fair amount has been spent on the car haha Quote Link to comment Share on other sites More sharing options...
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