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Zetec conversion heater not working

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I have a mk4 which I have recently converted to a zetec engine this week is the first time I have used it in the cold and the heater is stone cold I have drained and flushed it but the pipes are not getting hot but the car gets to halfway on the gauge and will sit there for hours, I have checked and the heater flap is moving, pouring boiling  water directly into the matrix gives a blast of warm air, 

Has anyone else done this conversion could the heater pipes be connected wrong? The top outlet on the heater matrix is going to the union on the retroford water rail

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I've done a Duratec conversion, which I believe is very similar in terms of the plumbing.  I'm not 100% certain, though, so someone on here might be a bit wiser on Zetec specifics.   The Duratec cooling system is a bit "backwards" in terms of how it is fitted together on the engine block - The thermostat is actually connected to the cold (lower) outlet of the radiator rather than the hot (upper) inlet from the water rail.  The only reason a mechanical thermostat operates at all in this position is because there is a hot water bypass connected to it directly from the water rail (this bypass is basically what I am using for my heater feed), which keeps the thermostat at close to the same temperature as the water rail.

 

If this is also the case on the Zetec, then you should probably connect the bottom hose of the heater matrix to the water rail rather than the top hose, as the water rail is the hot/pushing side of the system.  Otherwise, you might find your system is pumping in such a way that it is creating airlocks in the matrix rather than helping move them to the top for bleeding out - you'll also lose the top hose as a reliable bleed point.

 

A few other causes I could think of for your problems:
- There's an air lock or other block in the Matrix (Neo) - as above, but once you've plumbed it in, the top hose of the matrix is normally a reliable bleed point and a place you can check that the system is pumping correctly.

- broken coolant pump - also unlikely, as these tend to leak rather than just stop pumping.  Unless it's jammed and the belt is slipping over the pulley (would probably squeal horribly though).
- Connecting return side of the matrix to the wrong port of the thermostat or tee-ing it into the wrong radiator hose.


 

Edited by RichardJ

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Which engine are you running? I think the water pump on the 2 litre Mondeo will run the wrong way after the pas and Aircon pump have been removed and needs the focus or escort 1.8 pump fitting although apparently some have used the pump backwards without issue.

 

Even so you would probably get some flow through the heater matrix. 

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we changed the water pump as it had the wrong one in the box when we fitted it so when it got up to temp it pumped the water out, we are trying something tomorrow which hopefully works although i am sceptical

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