Discovery II Heater Problem

[disco007]

Discovery II 140,000

Water pump leaked so it was replaced it 2 weeks ago.

But no hot air from heater.

So took head off and had it checked, Pressure test ok but needed a light skim.

Replaced 1 hole gasket with new 3 hole gasket,

Fitted new thermostat and radiator flushed system out with hose.

Refilled and started the temp gauge goes up to mid point and holds but still no warm air from heater.

Hoses from heater. . . . . one side hot. . . . the other side much much cooler.

New radiator, top hose hot, bottom hose cool.

When refilling, held expansion vessel high out of cradle to try to remove air.

Any suggestions for next step ?

[sussex-landy]

I have had this on my early discovery and my range rover P38 its air in the heater matrix I had to rev the engine to clear it when it was cold in the morning with the cap off the tank so the air could be flushed through and feel the pipes to make sure its flowing around leave the heater off as its a pass through and the outlet pipe should get hot and if its not the heater wont do anything anyway. I found revving around 3000 rpm then letting it settle squeezing the pipes then revving again got it moving as its getting hot put the cap on the tank and run it upto normal temp then rev it some more and let it cool as you dont want ari blocking the thermostat and pushing it into bypass mode causing it to overheat.

I had a heater matrix with air for three weeks no heat and the temp sat in the middle but I was just cruising around under 2000 rpm so it never shifted it until I revved it up and down randomly.

If you get the heater working ok and cant feel any air in the pipes and it does it again chances are your introducing air through either the head gasket or slipped liner if you have checked for the basic leaks and stuff.

I wouldnt use the car unless you have to as its a dodgy situation if the air moves in a large volume and blocks a pipe somewhere, I had it happen to me and coolant blew out the tank all over the road.

[disco007]

Ran her up, even raised the front on a bank to try to help vent it but still the same,

Just a wild thought, when I replaced the cylinder head gasket, I used metal locating pins (genuine landrover ones) rather than the plastic ones, has anyone else done this and had problems?

[davyd8899]

was the head gasket displaying any other symptoms of failure, bubbles in expansion tank, oil and coolant mixing?

probably stating the obvious, but have you checked the flaps behind the dash?

failing that, blocked heater matrix? coolant flush?

metal dowles should help not hinder.

[disco007]

Head gasket showed signs of leaking into coolant, hence re skim.

There is no water in oil, I take your point re heater flaps but the hoses either side of the heater matrix are one hot, one cold.

I have flushed it all through removing all the hoses and putting a garden hose on one end to force through, and it is clear.

Would a compression test show a leaking head gasket.

I was so carefully clean when I replaced the head gasket and done 35Kn +90 +180 +45.

? ? ?

[dave88sw]

take the 2 pipes off that feed the heater from under the bonnet and push your garden hose in the end nice and tight to effect a seal. Run the hose and then change over to the other pipe, keep reversing the flow and you'll probably find a huge amount of carp comes out.

[sussex-landy]

At the end of the day when you go through everything it could be the cylinder liner, I had the same on a V8 where everything looked but the air kept coming back and the first thing it hits is the heater matrix, when I removed the heads I saw small amounts of rust colouring around the edges of cylinder 3 which none have so I assumed the liner was slipped but hadnt moved as they are better than the old ones but there is still seepage around the cylinder it appears so ran it for a while and checked and the spark plug was damp with water when I put it on a tissue, not sure if this happens on diesel and which yours is. I went through all the recommendations above and looped out the heater in the end to see if air was still getting into the system and moving around the engine as the heater wasnt there to capture it now and there was loads and it kept coming and coming.

If in doubt check the cylinder again for issues around the edge of the liner which will push air in and keep blocking the heater matrix, loop out the heater matrix and run it to be sure air is moving around. Mine hit 138000 and got much worse even though now i suspect it had been the source of issues over the last 12 months but the air was not enough to keep killing it and my oil was clean as it was burning off the small amount of leakage so there were no abvious signs and I just assumed it was head gaskets.

Could be build up in the heater as well if you squeeze the outlet pipe you should be able to feel the flow.

[davyd8899]

Fitted new thermostat and radiator flushed system out with hose.

when you say radiator do you mean heater matrix or radiator (stupid question i know) only asking as your having heater issues and not overheat issues

coolant flush in the matrix, leave it to soak then as said above hose over 1 pipe nice and tight and blow through, then alternate between pipes.

if this doesnt work or its a new matrix then air is getting in somewhere, could be a piston liner, on the K series engine a pressure test wont show up an annealed head (gone soft) though i dont know if the TD5 suffers with this fault.

[David Line]

I have a 2018 Land Rover Discovery which I think has an issue with the heater hot or cold air pipes not being connected up as not much flow gets through. Is this a known issue and is it easy to get to them to refit please?

[Escape]

It is a known problem on the later Discovery and Range Rover Sport, but it's (usually) not the pipes not being connected. The problem is the heater core has a tendency to gunk up internally, so less water flow and reduced heat output. You can try flushing it through a couple of times. The proper fix is to replace the heater core, but that required taking apart most of the dashboard...

[smallfry]

Also, a product like Radweld or Barrs Leaks can cause this. I would avoid using it at all costs, except in a dire emergency. Like stranded in central Africa for example.

I have found that using it will ultimately end up costing more than a tow home.