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post #74 of (permalink) Old 1st November 2008 Thread Starter
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If the heater core is indeed running freely with a garden hose attached to one pipe then logically it can't be that.

However...... I did find that new bits of gunk did dislodge & re-block the core fairly frequently at first...... a sludged-up system will have plenty of that ' goo ' elsewhere in the circuit.

Take a few minutes to double check the core IS still flowing.

If so...... the problem MUST be the flow FROM the engine OR the return pipe.

As someone else said above, an airlock WILL stop the flow, but so will a cold or stuck thermostat.

So what do you do?

a) re-check heater flow
b) check water flow from the engine ( heater pipes off) - is there any?
c) if 'b' OK, then check return pipe to engine is clear (hose?)
d) make sure the car is up to temp & stat open
e) Re-bleed air valve - ensure it IS actually clear with a bit of thin wire.
f) if necessary, temporarily 'crack' a hose joint or two to get air locks out.
g) Have known a couple of cars to have such badly worn / corroded water pump impeller vanes that there is almost no 'push' in the system..... i.e. (b) is there a good flow under some force from the output pipe? If a 'dribble' but pipe is clear - suspect stat or pump.

Hope this helps

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