Audi A3 1.9TDi overheating Problem

**darkocean** · 25-08-2010,12:33 PM

Hi
I'm new on the Forums,and have a problem with my 2000 A3 1.9Tdi.
The problem is when I am driving shortish distances the temp needle shoots up to 120 Deg then the warnings lights flash and beep.After a short period it dramatically drops down to 60 odd deg and then works its way back to 90 odd deg and stays there perfectly..
It is starting to do this more regularly now..I think it is the thermostat sticking maybe but am told there are 2 thermostats...?
Please help as I am worried I could be damaging the engine...

**Crasher** · 25-08-2010,01:35 PM

It could simply be a faulty coolant temperature sender which is on the side of the head above the gearbox and easy to change but only when the engine is cold, server scalding damager.

The other possibility is that the water pump is suffering from a loose impeller and this is a much more involved job as it means removing the cam belt. If it is the water pump, you could easily damage the engine.

I suggest you start with a fault code read on the engine and instruments to see what is stored. When it is hot, with the engine off, feel the lower radiator hose and see if it is as hot as the top one.

**darkocean** · 25-08-2010,01:59 PM

Thanks for the response.

would there be codes stored even if the display unit says everything is ok, the warning light only beeps and flashes for that brief period before the gauge shoots back down.
Surely if the impeller of the water gauge is damaged when i am driving normally it would be affecting the reading as well.Over long distances the temp stays around 92 deg , is this a normal reading..?
Thanks Again

**Crasher** · 25-08-2010,03:45 PM

The memory is non volatile; if the coolant temperature sender is faulty (extremely common) it is normally logged as a code, but not always.

If the temp stays stable over long distances, that suggests a failed cooling fan, do the fans come on?

**darkocean** · 25-08-2010,04:04 PM

Yes they do, it is very wierd as it does not always happen.Yesterday i drove it and it was fine, today it did it twice, and i was forced to pull over as i was concerned about damage to the engine

**Crasher** · 25-08-2010,04:13 PM

Have you checked the top and bottom hoses to see how there temperatures compare?

**darkocean** · 25-08-2010,04:36 PM

Will try that tonight, but surely if the temp spikes quickly and then back to normal both pipes would be hot then

**Crasher** · 25-08-2010,05:44 PM

The quick spike suggests coolant temp sender, the engine cannot heat/cool in fast spikes.

**darkocean** · 26-08-2010,09:13 AM

mmm good point,but say the thermostat was sticking though would you not get that result if it suddenly fully opened. I felt the pipes and they were both hot, however it was under the condition when it was fine.It did not replicate the problem again last night, damm fustrating thing...

I am going to go with your idea and replace the sensor and see if it happens again..

**Crasher** · 26-08-2010,10:06 AM

Thermostats can’t move that fast, their response is very slow. They tens to stick open or shut and not move, often they stick open which over cools the engine.