Land Rover Repair: Cooling problems TDI, land rover discovery, radiator leaks

Question
Hi John
I have a 1996 Land rover Discovery TDI, that used to be my wifes.  She was the second owner from 92000 km.  It now has almost 320000km on it.  To give you a bit of history on the problem, soon after she got it, it was found that the heater was leaking coolant.  Her dad spent some time pulling out the dash and found it to be one of the pipes from the firewall to the heater had corroded through.  a few years later the car developed an overheating problem.  The radiator was suspect and was found to be 70% blocked.  another few years later we have another overheating problem, the radiator was checked again and found to be 70% blocked again.  However it now had a suspect head.  We sent the car to Melbourne landrover (about 330km away) and they stripped down the head and found to be just the gasket.  The head was tested fine.  On the way home, about 50km away from Melbourne the car started to overheat again.  to cut along story shorter, the head was replaced and a 6 month warranty was given.  however the header tank on the radiator leaks coolant from the cap and there is a strong smell of coolant in the cabin.  We have 3 tdi discoveries in the family so I swapped header tank caps with one that was known to be functional but the same thing happened.  Suspecting that the header tank was coming pressurised it went back to Melbourne for a third time to get checked out.  They found a small leak at the water pump but the head tested fine.  (the header tank was replaced with the head if this helps.  Once again the car overheated on the way home from work.

Since then  I have re directed the heater hoses so the heater under the dash is taken out of the picture.  Since I have done this I no longer have the coolant smell so I suspect that something is not right under the dash, however I still get that chalky residue around the header tank, but It takes a few more km to get it there.  You can imagine how much money we have spent on this car trying to fix it.  I am not sure if it is fixed now, but It hasn't overheated since but the weather hasn't been that hot either.  The viscous fan was suspect but the overheating occurred at 110km/h so I think it is safe to take it out of the picture.  My theory is that somthing in the heater is perhaps corroding and blocking up the radiator and the head  was a result.  Have you come across anything like this ????
regards
Sheridan

Answer
Rarely seen a blocked front radiator (cooler matrix)
Mostly with these engines the problems are the follows:
- try to steam clean carefully the radator, be cause it usually blocked with dirt  between the reeds, so the air cannot go through.
- You should change the viscous fan assembly with another (from other disco), it's hard to make sure it's good.
- check the pressure it the tubes whet the engine is warmed,  and five minutes later too. If It's hard to press with hand than you already have a cylinder head or gasket problem.
Maybe it needs a planar grinding on that's surface.

Otherwise these engine's never overheating if these things are okay.

Maybe you should check the injector timing... (you cannot just in a workshop)