I know why I'm over heating ... It's because I'm losing water ...

Sorry abut this being my first post but I'm reall scratching my head. I'm an ex-pat Brit living in NYC who drives a V8 NAS defender.

I just drove 250 miles to Marthas vineyard from NYC, did another 100 pottering round the island ( saw 3 SW's and 2 series ) ... 150 miles into the trip back ... Temp rises a bit then on an uphill section climbs toward the red.

I stop and check the temp with ECUmate and it's about 104C, take the expansion bottle cap off ... There is pressure and it's half full.
I remove radiator filler plug and it's empty ... I refill with the fluid I have just for this occasion, massage top hose, fill into the top filler and put everything back. Drive maybe 5 10 miles with no issue, stop to get gas.

I buy a radiator leak stop and some more radiator fluid ( premixed)

Top up ( parked on a slope so radiator is up most ).

Massage hose etc etc.

Drive another hundred miles including some slowish traffic .... Hit the FDR drive in manhattan and it's over heating again. I stop and fill up again and drive the few miles home.

System seems to hold pressure but the top hose when parked nose down initially didn't seem to have water. I massaged it ... Heard some gurgling from the expansion bottle and then the hose is hot and clearly full.

I pressure tested the system a couple of weeks back ... Replaced a faulty hose and thought I'd solved it ...

I also did a gas test in the fluid for a blown head gasket and that seemed to be ok. The oil is beautifully clean ..

So now I'm scratching my head .... all I can think is head gasket but everyone tells me it would steam like a steam train the amount I'm losing ...

I attached a gratuitous photo of my truck on a ferry ... As people read threads with pictures and I need all the help I can get.

Head gasket or am I missing something?

Hi and :welcome:

Water pump or sticky thermostat possibly?

It may be an idea to introduce yourself in the appropriate section Here as this makes a number of people more amenable to replying.

Intro'd myself ... Apologies for barging in!

The thermostat is pretty new and so is the water pump ....

I did a basic intro and will post the all important pictures soon!

did you pressure test it hot or cold ? is rad getting hot allover core,all pipes etc ,4 litre blocks crack behind liner and give similar symptoms

I pressure tested cold ... I probably should do it hot as well?

I think the head is going to have to come off and new gaskets ... I'm planning a 300tdi conversion soon but would like to sort this in the mean time.