Potential problem perhaps

[petergalileo]

300TDi Discovery Auto.  Temp went up high, not quite to the red though, topped up coolant.  Went out to it this afternoon started fine, put it in drive and floored it, revved to about 1500RPM if that and just stayed there.  Then suddenly revs picked up again.

Its been using a lot of water lately, no smoke from exhaust at all and it purrs at tickover too.

Any ideas, I am thinking maybe the injectors need a clean perhaps, dont think its a head gasket, cant find the water leak either though.

Any advice or suggestions ??

Thanks

[dazzawhipple]

Check the engine oil is not milky if its milky headgasket gone

Also check the P Gasket on the water pump if its leaking there will be a stain of the bottom

Why its reving could be a ecu/sender problem

Darren

[Jimbo]

Td5's limit the revs and speed if the engine temp goes high - not sure if 300's do this as well ?

[petergalileo]

Doing it intermittently even when cool now.  Might drain the sedimenter tomorrow, maybe its been forgotten about and is full of dirt. but filter was clean when removed a week ago and changed.

[Budgie]

Could be head gasket, look for a pressurised water system when the engine is cold and a sheen of oil on the surface of the water in the header tank.
Your water could be going into one of the cylinders and out the exhaust, do you notice any steam from the exhaust on start-up?

The erratic revs could be engine oil getting into the cylinder so the engine is getting more fuel!!  :(
But I only said "could be".  

[petergalileo]

Absolutely no smoke from the exhaust apart from slight block puff on startup from cold.  

If water was getting into the engine I would get white smoke if it was oil I would get blue so I am pretty sure the head gasket is okay.  

I am putting it on a diagnostic system or rather a local garage is doing it for £30 tomorrow so will see if the sensors are okay.