Thread: Discovery 2 TD5 Post 2002 Radiator Confusion

Got a flow chart and can see that on my car, the fuel cooler/heater hose was connected to top "blanked off pipe", and oil cooler feed was running hot coolant back into bottom pipe (which happens to be restricted, as it was expecting to be connected to fuel cooler/warmer hose).
So confusion partly from trying to make sense of improperly installed hoses.
Can now see how to get rid of oil cooler hose as Dazza has indicated. Easier to follow with a picture.

TD5 flow .jpg


Have just spent much of morning trying to install new coolant hose to oil cooler. aaaaaarrrggghh.

Background info on the oil cooler - I have a silicone blockoff on my oil cooler and the new type radiator - where the upper spigot (normally connected to the oil cooler) is blanked off( see attachment) I have a thermistor in the oil cooler housing to measure the water temp there(image below).
It gets pretty hot in the oil cooler on a big pull - 120 Celcius.
This means with 50/50 coolant and a measured system pressure of 8 psi there is localised boiling there - see chart below which is in farenheit. At this temperature a lot of vapour will come out of solution. It cools off slowly when you back off - see image of cooling passages in the block to oil cooler.
Before you state that the system does not work at 8 psi - my system holds pressure very well - fully tested - and I have a pressure sensor on the overflow bottle - it runs at 7 -8 psi in normal ops at sea level.
I suspect LR engineers knew how hot it might get in the oil cooler from engine bench testing and that at elevated temperatures vapour would start to come out of solution( about 45-50% vapour at these temps).
The best place for coolant with a high content of vapour is to restrict its flow to increase pressure, and dump it into the coolest part of the circuit - far away from the low pressure entry point of the coolant pump where it would simply turn to foam. Hence it went into the lower part of the radiator through a restrictor - see image. Or perhaps it could have been sent straight to the overflow bottle.
I dont know how much of this vapour is returning to the main circuit with the oil cooler blocked off. With a new radiator the exit temperature from the radiator is 70-85 degrees C and the vapour will go back into solution.( I've measured it BTW with thermistor in lower hose)
The change in the spec on the current radiator would have been in response to common blockages there due to poor maintenance by your average joe. The bean counters would have gone for the cheapest solution and ignored the engineers - in my opinion - or maybe others can shed light on why the change.

With this extra vapour from the oil cooler housing being now routed back into the block (oil cooler blockoff added)and low system pressure due leaks and poor maintenance of coolant and radiator I believe that the cooling system will be operating close to its limit. Hope this gives some food for thought.