Birchall
Dick Chown Award 2016
Two of the cars I have bought recently (both TDIs) suffered from pretty much identical problems and it wasn't quite what I expected.
Both had temperature gauges that hardly moved off the 60 degree mark.
So I immediately thought it would just be a broken temperature sender.
I replaced the sensor on the first one and it made little difference so I jumped to a conclusion that the new tempo sensor was faulty (that happens more often than you would think), but no, even after another sensor change the problem persisted.
So there was only one culprit left, the thermostat. I must admit that I didn't think it could be that because if the temperature sender was working correctly it means that the engine was running at 60 degrees or less, even at motorway speeds (I know these TDIs don't give off a lot of heat, but not getting above 60 degrees, even under load???
I carried out one final test, I did the same run, but this time leaving the climate switched off (the theory was that with the climate on the electric fan runs regardless of engine temperature, so switching it off should see an increase in temperature. Sure enough the needle did start to rise and it hit 75 degrees.
To me that proves that the temp sender had NOT died completely at least.
So it did seem to point to a thermostat problem, so that was changed.
FIXED !!! The temperature rose to 90 (where it should be) quite quickly and stayed there, as it should !!!!
A few days later the other TDI (which I thought had a temp sender issue too) acted the same on a run with the climate switched off, the temp rose a little.
So today the thermostat was changed on that one and hey presto, a perfect temperature of 90 quickly showed and stayed there.
So if you have a TDI that is acting like the sender has failed, try the same check, switch off the climate and see if the temp rises. If it does, you have a failed thermostat. They are reasonably cheap and pretty easy to replace on the TDI AMF engine at least. They are in the front and the alternator mounting is slightly in the way, but it is a DIY job.
I hope this helps if you have similar issues.
Steve B
Both had temperature gauges that hardly moved off the 60 degree mark.
So I immediately thought it would just be a broken temperature sender.
I replaced the sensor on the first one and it made little difference so I jumped to a conclusion that the new tempo sensor was faulty (that happens more often than you would think), but no, even after another sensor change the problem persisted.
So there was only one culprit left, the thermostat. I must admit that I didn't think it could be that because if the temperature sender was working correctly it means that the engine was running at 60 degrees or less, even at motorway speeds (I know these TDIs don't give off a lot of heat, but not getting above 60 degrees, even under load???
I carried out one final test, I did the same run, but this time leaving the climate switched off (the theory was that with the climate on the electric fan runs regardless of engine temperature, so switching it off should see an increase in temperature. Sure enough the needle did start to rise and it hit 75 degrees.
To me that proves that the temp sender had NOT died completely at least.
So it did seem to point to a thermostat problem, so that was changed.
FIXED !!! The temperature rose to 90 (where it should be) quite quickly and stayed there, as it should !!!!
A few days later the other TDI (which I thought had a temp sender issue too) acted the same on a run with the climate switched off, the temp rose a little.
So today the thermostat was changed on that one and hey presto, a perfect temperature of 90 quickly showed and stayed there.
So if you have a TDI that is acting like the sender has failed, try the same check, switch off the climate and see if the temp rises. If it does, you have a failed thermostat. They are reasonably cheap and pretty easy to replace on the TDI AMF engine at least. They are in the front and the alternator mounting is slightly in the way, but it is a DIY job.
I hope this helps if you have similar issues.
Steve B