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[neilr]

as above both pipes ar hot in and out of heater rad also to pump but there is no heat at any of the vents anyone have any suggestions please. Ita a 2001 2.6

[Kneepad]

I believe, one test you could do is to remove the vacuum hose from the Heater Bypass Valve and see if get any heat through to the cabin. 

[Welung666]

As the pipes are hot my best guess would be a clogged up matrix. Have a look at the maintenance guide index for Jimbob's flushing the heater matrix HowTo

[Bionic]

Thats about right. The heater matrix is probably clogged (mine was). A new matrix sorted the heat out but it was a sod of a job to do!
I did try all suggested ways to flush and clean it before ordering the new matrix and none of it worked. Even with a very high pressure hose attached!
Its lovely to have heat now though................

[mark.adams]

Has anyone come up with a successful radweld removal chemical that could be flushed through the matrix?

[neilr]

if both pipes are hot would that not suggest matrix is flowing or am I being daft.

[Andy B]

if both pipes are hot would that not suggest matrix is flowing or am I being daft.

You're not, that was my thoughts too. 

[alcutler]

if both pipes are hot would that not suggest matrix is flowing or am I being daft.

Unless the hot water is only getting through the top part of the matrix and leaving via the exit hose -  with the main body of the matrix being clogged. Can access be gained to the bottom of the matrix to feel if it is hot down there?

[alcutler]

Has anyone come up with a successful radweld removal chemical that could be flushed through the matrix?

:-?I once managed to unclog a radiator on an Astra diesel  that was really bad (the bottom hose hole was virtually blocked solid with gunk) - using Central Heating system descaler - used a strong mix and left it to soak for almost a week but it shifted it and the amount of rubbish that flushed out at the end was incredible. Got the descaler from Screwfix. Could be worth a try with the matrix in position followed by a good flush after.
 

[neilr]

Flushed heater matrix today water was rusty brown. Strange as water in header tank is bright pink. So welung was right and I now have heat in car. But why should the matrix block like that and not contamiate rest of system. Could the heater pump be naff.

[Abiton]

Flushed heater matrix today water was rusty brown. Strange as water in header tank is bright pink. So welung was right and I now have heat in car. But why should the matrix block like that and not contamiate rest of system. Could the heater pump be naff.

Simply because it contains the narrowest coolant passages in the whole system, and a baker's dozen of them in parallel. 
If you have a look at this piccy, you can see how small the individual pipes are:


What I hadn't appreciated when I took that piccy is that inside each alloy tube (behind the plastic end fitting), there's a spiral plastic 'core' which further narrows the flow paths (but improves the heat-transfer to the tube walls and so the passing air, I assume).

Since they are all in parallel from the main in to out pipes, they can selectively fill up with sludge without there being a sudden problem, more of a gradual deterioration of flow. 

Since there are other ways the coolant can 'choose' if the matrix is getting clogged, there's no 'self-clearing' behaviour, unfortunately.  Only a damn good flushing of the matrix itself can help.   

[neilr]

Thanks for pic. Set the hose on for a good 15 minutes reverse flow 1st then std flow and back to reverse 5 mins a piece water was crystal clear

[Malcolm_D]

Flushed heater matrix today water was rusty brown. Strange as water in header tank is bright pink. So welung was right and I now have heat in car. But why should the matrix block like that and not contamiate rest of system. Could the heater pump be naff.

Mine was the same, no heat, no evidence of brown gunge in the rest of the system but when I flushed the matrix it was clearly choked with the stuff. I would imagine that it is the flushing in both directions that dislodges it and then clears it.  Doesn't mean that anything else is faulty.
Far rather do this than replace the matrix - they are a pig to do 

[Abiton]

Personally, I can't think of any reason that flushing one way rather than the other makes any difference, it's all kinda symmetrical in there.  But hey, it can't do any harm, and while you're at it, the more flushing the merrier.

Just don't assume that because you're squirting your hose in one 'big' pipe and it's flowing well out of t'other, that all the little inner pipes are clear; keep at it, and max out that hose flow. Pop some random bit of hose on the current 'exit' hose, down to the deck, to prevent you drenching the engine bay, and ideally seal the hosepipe to the current 'entry' hose for the same reason, and to maximise flow.

May as well do it once and well than have to revisit, let alone change a non-leaking matrix.  :-?

N.B. This advice isn't aimed at the OP, who has solved his problem courtesy of the ever-generous Welung, it's more for general information, or my best attempt at it. 

[Boatboy]

Flushed heater matrix today water was rusty brown. Strange as water in header tank is bright pink. So welung was right and I now have heat in car. But why should the matrix block like that and not contaminate rest of system. Could the heater pump be naff.

Wonder if yo have any cold spots in your main rad? Same principle applies - too many alternative routes = low flow rates through each narrow channel.

Steve