Thread: overheated disco - core plug problem

Helloo. Just dropping a line here to say HI and HELP ...
I will try and post this in the right place too - but first things first!

I have a Discovery 94, 300TDI combined with LPG. Just bought about 6 months ago. Odometer reads over 400k - rebuilt is suspected to have been done about 100k ago... but there is no papers for evidence.
HOWEVER - it ran beautiful all day, every day - no oil or water leaks... only slight problem was occasional dark smoke under "load" (e.g. 5th gear uphill).

WELL. a few weeks ago while driving on the freeway for about half an hour, engine overheated and after immediately pulling over we heard a slight "plop" and a heap of water and steam escaped at the back end of the engine.
After cooling down it turns out the core plug in the cylinder head has popped out....
I'm now trying to find out what happened.
my theorie at the moment is that the water pump or thermostat failed....

Dont know if this could be evidence of the water pump giving up, but the previous weeks (since winter hit Perth really) the fan belt started squeaking terribly in the mornings - I put it off to the cold and wet... tried belt grip a few times, but it didnt seem to make much difference for more than 10 minutes or so....

Well.. I am hoping that someone can give us some advise how to go about checking the thermostat / waterpump... I will take the head off this weekend to put a new core plug in (it is very inaccessible!) and get the head tested for warping etc... (lets hope this did not happen!!)

Thanks in advance... S I M O N E

Hi,
welcome to the joys of Disco ownership you too! Firstly, dark smoke under acceleration in your car is pretty normal, no concern whatsoever. Secondly, your trouble experienced needs further investigation. The core plug popping out (have never heard about such, in fact) indicates increased pressure in the system, the reason for this might be a head gasket failure, but even other possibilities exist. So you need to check that out. Make also the effort checking the cap of the expansion tank, or swap it anyway as it doesn't cost the earth and may well have contributed to your problem.
If the water pump seems to trouble you, replace it. It is not uncommon to give up, I have been through two or three of them over the years. Make sure you mount it correctly, sometimes these items are mounted with the pulley ever so slightly out of alignment that it will wear out rather quickly (the main reason for its failure) and this is usually accompanied by the belt squealing.
To test the thermostat you suspend it in a pot with water and a thermometer. Then you heat the water and watch if the thermostat opens at the specified temperature (should be stamped somewhere). If in doubt, replace.
It is well worth checking the head after severe overheating.
Good luck!!!!