Temperature problems

[Carles20vt]

Hi guys,

I have a temperature problem with Coupe Quattro KV Engine (5 cyl 10v).

I have bought and don't see temp problems but latter it appeared. I have changed water pump, transmission belts, radiator, coolant G12+, new radiator temp sensor and purged air (two screws, one at radiator and other at tube)

When it runs stopped, it puts at 90 + 2 steps. Starts the fan at the first run. Latter it increase until first point and fan runs some times at first run. If you move it at highway it runs at 90 + 2 steps. But if you go faster or do a more aggressive conduction it starts to increase above first point and coolant go out When it occurs, the second run of fan don't start and I have checked that it runs if I make a point at sensors connector (sensor is new).

Coolant don't have burbles, oil and when engine stops and decrease temp, no pressure accumulation at circuit.

What could happen? I don't know what to do at these point Some dirty part of circuit? It seems to have a very high temp part and other more low... or bad pressure... I don't know.

Thanks in advance!

[newsh]

Did you try changing the thermostat?

Take off the coolant reservoir cap and shake it, if it does not rattle try a new one.

Otherwise, maybe head gasket or crack in head?

[Carles20vt]

Did you try changing the thermostat?

Take off the coolant reservoir cap and shake it, if it does not rattle try a new one.

Otherwise, maybe head gasket or crack in head?

Yes, thermostat is replaced and chequed. We have other Coupe dead (valves pissed) that was very cold when it was running. We interchanged principal radiator and auxiliary radiator and both are clean an good condition.

Water pump, radiator fan sensor, etc. all new.

If check temperatures with a laser gun thermometer, we could see that the most hotter part is auxiliary radiator and thermostat zone. But principal radiator and other tubes and pipes are ok, so it's the cause because don't start fan or if start, it runs ony few seconds.

So we are thinking that someone at engine cooling part is dirty making only a few flux of coolant pass through engine. But I don't know how to check or clean...

Any ideas? These car are making us crazy...