Thread: Discovery 3 4.0 V6 head gasket? EGR causing water to turn black

Hi Izzyj6
To be honest with you I have never heard of coolant going black before. The garage you took the car to to get the pump changed was it a LR garage / agent or someone else? If they put a non LR coolant in the system this might have an adverse effect on any remaining coolant left in the system.

If the engine temperature is good and you aren't using any coolant I would go for a flush first and reassess. Personally I have never used a TK tester to verify the condition of the cooling system. Me I use temperature and level, plus I consistently use the same coolant, I have found the Tojo and the Nissan coolants to be good as well as The LR coolant when you use the same coolant all the time. Despite the coolant being RED there are subtler differences.

Maybe try a flush first.

The red OAT coolant turns black as it ages and is exposed to air.I would check if there hasnt been a shandy of red and green coolants used,not good.
Flush the system out,running it on water alone for a week or so then drain again and use the correct coolant.
Pretty sure all Land Rovers from about 1999 use the red OAT coolant.
You can buy it in 20lt drums pre-mixed from Westrac in Guildford,around $120.The CAT ELC Coolant exceeds Land Rover specs,I used it in both my TD5 Landys.
You should be able to tell if its a head gasket,it will either leak out of the cylinder heads down the block,turn the engine oil milky or pressurise the cooling system.Check for radiator hoses that are expanded/bulging whilst hot.Fit a catch bottle,plastic coke bottle is fine in the engine bay next to the overflow bottle.Put its overflow hose into the bottle.You can then monitor if there is coolant loss due to expansion in the cooling system(exhaust gas taking the place of coolant).If you are loosing coolant thru the overflow bottle,try a new cap,it could be that simple.
Goodluck.
Andrew