hi rebuilt my 4.0ltr running in now.
noticed the temp gauge went up a bit then down again.
could this be because every thing is new and bedding in.
bleeded the water system to remove air.
also now thinking about changing oil again now i have run the engine, just to be on the safe side.
it could be running a little hot but not boiled over yet.

many thanks

mine was the same mate for a couple of weeks after a rebuild,just before it blew up.................only joking does seem a little strange though but bleeding the air from the coolant system could be the remedy.

My 3.9 disco rebuild is the same, as you've probably noticed from my other posts. Next I'm trying to replace the water pump. Unlike you I'm not 100% sure I have a good block.

Thanks,
Roger

How would block effect this? Not been funny, just out of interest...

as a rule o thumb always replace the rad and water pump and state as it is easy when out.
yes they do run a tad hoter than normal when first running to bleed the air out unless you fill with hot water first to open the state and help bleeding or use a vac fill system to eliminate any air as i do.
unless you are fitting a new top hat linered engine it is pure folly to fit a used engine unless it has been pressure tested to confirm a 100% good block and then i would still fill with irontite sealant!

when the block goes porus tiny holes are exposed between the coolant jacket and the cylinder bore depending where they are could mean either pressuising the cooling system(most coman) or it sucks and burns water from the cooling system! in some cases this means that you don't have enough coolant and overheat