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

[izzyj6]

Hiya sorry I am new to this so bare with me and yes sorry my spelling and grammar isn't the best ever. I have not long since brought a disco 3 4.0 v6. when I got it after a few days I noticed it was using water so I booked it in a garage and they said the water pump and head was gone. so I took it back to the garage where I brought it from and they put a new pump on it for me and said there was nothing wrong with the head. I drove it for around 300k and it seamed fine no over heating or not even getting hot but for peace of mind I put it in a different garage to get a second opinion and got them to check it for me. when they first TK tested it if passed and then they took it for a drive and it failed. I took it back to the garage again where I brought it from and they still said its fine and takes a while to fail the TK test so its not a positive reading and as its not getting hot there's nothing they have to do. iv been in touch with fair trading and even they said that the TK test isn't a strong enough test to prove anything and as its not getting hot they don't have to do anything. I checked my water today and its gone black over around 300-400k this worries me but I have been doing some reading up and I was wondering if it could be the egr valve causing this and for it to fail the TK test or has anyone ells had this problem or any advise would be gate thanks. sorry for the essay

[Nomad9]

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.

[LandyAndy]

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

[izzyj6]

thanks for the replies
no the water pump was fitted in the garage where I got the disco from it took them 4 weeks as they had to get the pump from the uk as there wasn't one in Australia apparently.

ok thanks ill do a flush next weekend and see how it goes thanks.