zx heater

[tony1961]

Hi all.
For the last couple of winters, my wifes runaround, ZX N reg dt. The heater dosnt blow hot. There is a very slight difference between adjusting the temp control knob from, cold to hot. The engine thermostat has been changed and made no difference. Could this be the dreaded matrix. The coolant all looks ok. any ideas.
Adjusted the rear shoes, fit a tail light bulb @ 60pence. Took it for mot, Passed!! 170,000+ miles.

Many Thanks Regards Tony.

[Stewart(oily)]

Possibly the matrix is blocked or full of air ?

[tony1961]

hi. Already bled the system only water comes out of all the bleed valves. done this quite a few times thanks Tony

[Hell Razor5543]

Just a thought. Set the heater control to maximum temperature and then try bleeding the coolant system again. IIRC there may be a valve that lets coolant through the matrix, and when this is closed it can act as a bit of an airlock, letting coolant out if you drain the system but not letting replacement coolant back in. I had this happen on my BX.

[tony1961]

Hi, cant remember if i tried it with heater on max . will try tomorrow or monday. thanks Tony

[citronut]

i dont remember if the ZX has a coolant valve at the heater matrix as the BX dose,

on a BX i used to own we had no heat the first winter, till i took the valve apart which is like two plastic slues gates, on dismantling these i found both to be clogged solid with what looked like two OXO cubes,

obviously previous owners had applied copious amounts of doggy pellet type rad weld into the cooling system,

after clearing this all out the heater worked overtime ( toasty toes ),

the very next winter we went through the same saga so there was obviously still some lurking in the system,

after this second clearing of the OXO cubes we had no more problems

[tony1961]

Would the valve be behind the dash, theres nothing in engine compartment. What does the temp knob do ? does it restrict the water flow.

[citronut]

again if like the BX the valve is inside the cab attached between the matrix and the coolant hoses were they enter the cab/bulkhead,

and the controls operate cables and levers