my brother has a 03 Range Rover with the BMW engine. Within the last 3 months we have installed 3 coolant tanks in this pos.. they keep cracking at the seems. Yes im using an aftermaket part and yes its under parts warranty each time. but what is really going on. ****ty parts on possible bad head gasket?

 

Maybe. Coolant jug has pressure relief cap that holds 15 - 18 PSI, then vents. So if you are producing combustion gas in coolant, you'll normally have overheating and can have sounds of water running through pipes under the dash. There is a chemical test you can buy from auto parts store that tests for combustion gas in coolant, it is $35 - $50, and can test multiple cars (like 16 times). That is pretty sure thing for HG problems. If you are producing that much steam or exhaust gas pressure, a gasket is leaking somewhere. Don't trust the heat gauge, the ECM monitors the temp sensor and sets gauge to 9:00 position for a wide variation in temps. Plug in a scanner or an ultra gauge to see real temp.

 

I would say the coolant bottle and possible issue with the electric thermostat. might need an update. Been a while but if it wasn't done it will overheat.