No flow through heater matrix despite being clean & bled

Forum for Engine, Exhaust, Drivetrain, ECU
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kdillon
Posts: 2
Joined: Fri Mar 30, 2018 6:54 pm
Qashqai Model: Mk.1 Qashqai - J10 (2006–2013)

Post by kdillon »

Hi,
I'm seeking help with a problem on my 1.5 Dci with the heating system. The heating matrix has been isolated and flushed with water, no problem there. The whole cooling system has been drained and refilled taking particular care to ensure there is no airlock in the heater matrix. After running the car at normal working temperature (half an hour) the cooling system is operating normally in that the pipe work is all warm except for the two pipes entering and leaving the heater matrix; there is no flow through it and a cold cabin. The thermostat has been replaced and the water pump is pumping water through the system.
I've run out of ideas, for example is there a valve on the engine that may be preventing any flow to the heater matrix?
Your suggestions please.
Thanks,
Kevin

kdillon
Posts: 2
Joined: Fri Mar 30, 2018 6:54 pm
Qashqai Model: Mk.1 Qashqai - J10 (2006–2013)

Post by kdillon »

Problem resolved:
I did some further testing on the isolated heater matrix and found that although I could demonstrate a decent flow rate using mains water pressure a much lower pressure (such as provided by the engine driven water pump) provided a mere dribble through the matrix. Realising the matrix was useless like this, I tried leaving it filled with white vinegar overnight and flushed it afterwards using mains pressure. This produced plenty of lime-scale residue and an improved flow rate. The unit is now working adequately; not new or ideal, but good enough to make the car serviceable.
I may have shortened the matrix life with the acid (already 9 years old) but if it fails at least I know what has to be replaced.
Bob d
Posts: 86
Joined: Tue Jun 21, 2016 10:02 am
Location: Not as far south as the Isle of Wight

Post by Bob d »

Thanks for sharing the symptoms and "cure". I doubt the vinegar itself will have caused any significant reduction in service life, more likely to be long term corrosion. I'd be inclined to try a dose of Viakal or similar for half an hour or so if it really is only limescale that's coming out.
J11 QQ N-Tec+ 1.5 DCi Magnetic Red
Gardarerlingsson
Posts: 1
Joined: Thu Feb 21, 2019 6:32 pm
Qashqai Model: Mk.1 Qashqai - J10 (2006–2013)

Post by Gardarerlingsson »

Hi all.

I am new to this group and i have a Qashquai j10 2008 which was having troubles with the heat. I replaced the water pump cleaned out the cooling system (at a professional shop) and replaced the climate control box. And...i replaced the thermostat. Well there are two thermostats, upper for the engine and lower for the heating system. Next week i will replace the thermostat and will post the results. I was really running out of ideas and i am quite confident that this is the issue.
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