Power, Temp and Hot Air

My 2000 TD5 Discovery II recently started to lose some water. I have also had problems with the Aircon running cold even when set to Hi. Another problem is that occsionally the power seems to level out. I cant accelerate or increase rpm. When this happens the temp gauge rises from its 50 % norm to just under the red line. After about 20-30 seconds all returns to normal an the temp starts to drop back to normal. There is no sign of water around the oil filler cap and my local mechanic doesn't think the head gasket has gone.

Any ideas?

Thanks

Rich:doh:

The aircon is a separate system apart from the need for electricity for the controls and the engine to drive the compressor, so nothing on there should relate to the engine side.

The loss of power suggest you may have fuel problems, you should check that the fuel pump is good (what miles has it covered?) there's a filter in the fuel pump itself, a filter down on the chassis by the rear wheel arch, plus there's a pressure regulator on the engine. See attached picture.

Peter

The rapid rise and fall of the temperature could be due to a failing waterpump, coolant temp sensor, expansion cap or thermostat or it could be an electrical fault.

The loss of power could be down to a fuel fault as lister has said but I think that it's more likely to be limp mode protecting the engine.

Try holding onto the coolant pipes and revving the engine to see if you can feel the coolant pressure rising and falling with the revs. This should help highlight a waterpump or thermostat fault. Have a look for signs of coolant around the expansion tank area. It is often a sign of a weak cap. If that fails then try a new temp sensor. The rough prices for the above are........

Thermostat £15
Waterpump £30
Coolant temp sensor £15
Rad cap £5