I've got a 2004 disco 2 with a 4.0 in it. It has a donor motor to get the rover running, I got it as a birthday present a year ago and finally got it running. The motor came out of a wrecked d2, its had the hgs done in the past but not sure when. I've replaced every single piece of cooling system known to man on this thing minus the heater core but it still runs hot. I've bleed it more times than I can count, put the lower temp tstat in and it still runs hot. It runs hot when I really push it, usually in the sand or up hills. I got it hot once going up a long hill, about 2 miles, that's kinda sandy. I had it in high range, it got hot approaching the red, I let it cool down and went down the hill. I went back up in low range and the temp gauge didnt even budge. I took it down to the creek in the sand and had it in low range and had to climb a few steep banks where i was really digging and pushing it and it got into the red before i could even get on flat ground.

I'm at a loss of what to do next. I've got a scan gauge coming to check temps and look at any codes I've got. I'm going to put some purple ice in it too for now. I thought I read somewhere that the computer needs to be setup for only a 4.0 or 4.6 to work properly. Would my computer not be tuned right for the 4.0 if its supposed to have a 4.6 instead causing it to run too rich or lean and causing excess heat? Or could it in fact be the hgs even though they've been done already or even slipped sleeves? There's no oil in the water or water in oil and I'm not loosing any water, or burning it. Is there something I'm missing that anyone has any input on? I dont know what to do at this point other than look for a 4.6 kit and rebuild this one from the ground up.

 

I had a similar problem. Turned out i didn’t have a low temp thermostat even though that’s what I ordered. Verify you have a genuine low thermostat and that is functioning properly.

 

I verified myself about 10 times before I bought it to make sure I bought the right one. I dont remember all the nomenclature but it's the real deal that everyone says to get.

 

Did you verify it after you bought it?

 

where did you buy it

 

Yeah verified after purchasing too. Part #PEL500110. I bought it on amazon. Feel free to correct me if that's the wrong one, I just want to figure this thing out I just dont know what else it could be unless flow is plugged up somewhere. I forgot to mention that my hoses swell a little bit whenever I've been running the rover. They are all brand new hoses too, not sure if they are supposed to but seems kinda odd to me.

 

Yeah I bought it on amazon too. Junk. Buy the one from lucky8.

 

They're all gonna be junk if it's not stamped 78C. If it's black and stamped 78C = good. If it's black and stamped 82C = 99.9% pure crap. Honestly though the 33.00 Motorad from Auto Zone has been a 180F stat no problems on the last few I did for people.

 

probably the last place you want to get it from
lots of reports including me lucky 8 sells crap thermostats

78 c stamped bearmach has them. Cheap

 

Try flushing the heater core