heater blows cold

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alan morgan

Active Member
Posts
110
Location
oxford.
hi i have a 51 plate td5 auto 120000 on the clock some months ago heater was only blowing cold flushed out the cooling system changed the thermostat and all returned to normal. now the heater when the temp gauge is mid way engine warmed up will only blow hot when driving as soon as i stop after a short while blows cold. start to drive and after a short while blows hot again ???? whether it is connected or not sometimes when i am driving there is a strange noise which seems to be coming from the dash area it sounds like some ones tummy rumbling fairly loud . any one any ideas? many thanks.
 
did you fill and bleed the system by the book?... which means raised tank, etc...if not there's air left in the system IMO.... bleed it well
 
raised the tank bubbles of air came out the bleed screw for about 15 mins. bingo heater now blows out like a furnice many thanks.
 
alan morgan said:
raised the tank bubbles of air came out the bleed screw for about 15 mins. bingo heater now blows out like a furnice many thanks.
Click to expand...

that's always the first call, as with the tank in place the bleed hole is above the coolant level so air is always trapped in there, from now on always lift the tank above the bleed hole when you fill the system untill a clear flow of coolant is coming out ... i'm glad it's not HGF
 
My Discovery 2 is warmer with Calgon!

Thought I would add a note about my own Discovery 2 and the heater problem. I have owned the car for 2 years now (bought without much history or service record) and must say that the heater was never that hot. Over the last 12 months though its been getting weaker and weaker till just before Christmas when it was a case of "Car Keys, hat, gloves, scarf, hot drink".

Much reading on here and the numerous mentions of the dreaded HGF were checked and found to be all OK. Then one day while standing looking under the bonnet and a little more head scratching and having read several things about the heater matrix being such a complete pig to replace I noticed the hoses to and from the matrix were neither as firm or as hot as the other hoses? I had of course bleed the system with the tank raised (thanks for that tip) and did notice that it seemed to take for ever to do so.

Battled the clips on the hoses (Now replaced) and removed the top hose to find a very clogged hose with what looked like lime scale lining the entire hose. Running a hosepipe directly into the top hose resulted in a very week flow from the other end. Removing the lower hose also showed the same lime scale build up. Looking at the other hoses it appears that the larger hoses have at some time been replaced but not the ones to the matrix.

So..........
A couple of cable ties held the 2 hoses to to Matrix vertical and a week mixture of warm water and a dissolved Calgon tablet were pored in one pipe till it emerged from the other end.

Leave overnight........

Next morning there is a layer of scum in the water surface which was promising but was nothing compared with what came out of the matrix when the pipes were released and lowered. A grey sludge resembling porridge came out of the lower pipe which when examined was limescale! exactly the same as you find in the bottom of the kettle in hard water areas. Only much, much worse. Once the initial sludge had come out the hose pipe was directed into the top pipe and OMG out came the most disgusting slurry. Ran the hose one way till the water ran clear then back flowed through the lower pipe to dislodge what was left.

Connected up the lower pipe and ran clean water into the top pipe and hey presto a clear strong flow right around the engine. Finally connected up the hoses, bleed the entire system, including a good coolant and sparked up the engine. Almost instantly you could feel the difference in the hoses going to and from the matrix. Best of all the heater was hot very quickly. Engine seems to be running better and smoother and we are warm and toasty!!

I realise this is probably NOT recommended but it has worked for us.
 
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