[chestnutree]

Hi everyone,
Been a long time since I posted here.
A family member has purchased an x reg fiesta mk4. I've been posting on a fiesta forum but still not got it fixed yet. As the cars are almost identical I thought I'd be cheeky and see if some old friends on here could help.
We were getting classic symptoms of a failed HCV when we were getting no heat. I've replaced the HCV but still no heat :/
To double check the new hcv is working, I removed the back right pipe coming out of the hcv which feeds the matrix, set the heater to cold and started the engine. No water came out. I then turned the heater to full heat and water shot straight out with full flow. Back to cold and it stopped again. Brilliant, so the new HCV works fine but why no heat still?
I put the pipe back on, removed the pipe out that of the back of the hcv on the left this time which is the return from the matrix. Set the heater to hot and started the engine. No water is returning from the matrix at all apart from a slightest dribble which was probably left in there. I kept squeezing pipes around this area and the engine in case of blockages or air locks to try and shift it but nothing would get any water flowing.
I put all of the pipes back and ran the engine with the coolant tank cap off and carried on squeezing pipes as I have read this is how you can bleed the system of any air locks. Still no heat after an hour
So for some reason the water doesn't appear to want to flow around the matrix. But why, what's blocking it? All of the pipes seem clear, there's no gunk or anything in them. No parts of the old hcv broke off and went inside.
I was thinking I could attach the garden hose to try and flush it hoping the extra water pressure should shift it but the hose won't reach using the jet wash will give me just enough extra hose length to get to it, but I would be worried that the extra pressure would be too much for an old matrix?
Any ideas or anyone come across this before? Please help
Nick

[JHT1888]

Hi Nick ,

I know you said the pipes look fine? maybe the pipes need replacing though ? matrix might need replaced?

This post has been edited by JHT1888: 23 February 2014 - 01:04 PM

[chestnutree]

J, you're still here? Been some time
The pipes aren't brittle and look perfectly clear on the inside ( the coolant pipes going to and from the hcv)
Might need a new matrix..... But why? I thought the only time a matrix needed replacing was if it leaked. It's simply a series of pipes which water flows through.... No electrics or moving parts. I'm stumped.

[JHT1888]

chestnutree, on 23 February 2014 - 01:09 PM, said:

J, you're still here? Been some time
The pipes aren't brittle and look perfectly clear on the inside ( the coolant pipes going to and from the hcv)
Might need a new matrix..... But why? I thought the only time a matrix needed replacing was if it leaked. It's simply a series of pipes which water flows through.... No electrics or moving parts. I'm stumped.

Been a long time

if there is no leaks coming from the pipes or anywhere else and no airlocks and the water coolant levels are ok the problem may be something else I know the heater box can go on fiestas maybe that ?

[chestnutree]

I know it's down to something with the matrix because no water is flowing through it and back up :/

[JHT1888]

have you tried using a degreaser in the header for awhile d/c the pipes from the engine bay into the matrix again and try degrease them

[chestnutree]

No. I can't get any water to flow down into there for it to work

[happy-kat]

Did you replace the HCV with a Ford item or an ebay bargain?
Only the latter have on may occasions not fixed the problems as beem faulty themselves.
Might be related.
http://www.pumapeopl...ndpost&p=931457

[JHT1888]

what about the control unit could that possibly be faulty ?

[chestnutree]

Ah happy-Kat still around too
Just had a read of that post. It was a hcv off eBay, but I believe it to be working fine.
I removed the pipe out of the back of the hcv which feeds the matrix. With the heater set to cold no water at all comes through, set the heater to hot and water instantly passes through the hcv out of the back where it would feed the matrix if the pipe was connected.
The bypass through the hcv is also flowing freely because both pipes at the engine side of the hcv get hot, coolant is flowing around the engine and it's not overheating. For these reasons I believe the new hcv is fine which leaves me thinking the matrix has some sort of blockage. Anyone sure whether or not flushing the matrix with a jet wash would cause any damage?

[JHT1888]

not sure on the latter, how is the thermostat is that looking normal ?

is there any splits on the pipes ?

[chestnutree]

No splits, all in tact. How do I check the thermostat?

[JHT1888]

It's quite a job to remove it to see it need to remove the alternator and radiator. when you start the car up how long before the needle reaches half way point if it does ? does it stay there or go back down?