Heater hot/cold switch stuck on hot.

[Cowhorns]

Hi everyone
The knob on my heater on my F4 R2109 is stuck on heat. it means I cant put the fan on without hot air coming out. Not ideal here in the south of France.... I took off the knob and the plastic cover. Behind that there is the rad itself and I looked at taking that plate off but it seemed a much bigger step once the nuts were off as it will involve pulling out the heating radiator. So I sprayed the switch with loads of WD 40 and so far it hasnt shifted at all. I there something else I can do? I'm loathed to really force it as the switch may break off.
Any assistance/ideas gratefully received.
Thanks

 

[jcarruthers2]

Hi

Sometimes the screw holding the plastic knob becomes loose and it prevents you from turning the brass heater tap on or off or this can happen too when the square end of the heater tap spindle is not seated correctly in the square recess at the back of the knob . However, the heater taps do seize up. Have you tried spraying the circular base around the bottom end of the heater tap spindle with wd40 with the spindle gripped with a pair mull grips and wiggling the spindle whilst spraying? This might free it up. If this does not work, you will have to take the heater tap off, then try to free it up with lubricant, clean off with emery paper, change the rubber seal and refit with a new gasket. If still unable to free up, you will have to fit a new brass heater tap.

 

[Cowhorns]

Thanks. I'll try again to loosen it. Will I have to drain the heater to remove the tap etc?

 

[jcarruthers2]

Hi

You will lose some coolant if you remove the heater tap alone and leave the heater matrix in situ. You would just need to remove the hose connected to the tap and the x2 nuts which secure the heater tap in place (lots of wd40 on these as they do tend to get rusty). Sometimes if you wiggle the tap off gently, you can get away with not splitting the gasket. However, it is much easier to work on the tap and matrix if you take them out together in one go. You will need to bleed the cooling system, once everything is fitted back to remove any air locks in the cooling system.

 

[Cowhorns]

Thanks!

 

[Cowhorns]

I managed to free the tap so it now turns. Unfortunately it now leaks too from the spindle by the look of it. I havent taken out the matrix or taken off the tap yet bit will do. I guess I can make a rubber gasket for it to re-attach if that is the problem but given how the tap was pretty well seized it might be something inside the tap itself. You mentioned a rubber seal above, is this in the tap itself? Do you know where I can get this seal anywhere and is is very difficult to fit? Thanks

 

[jcarruthers2]

Hi

The rubber O ring is located at the base of the spindle, you would need to remove the pin and fish out the remnants of the old O ring. It is a pretty straightforward job to do.Ensure the spindle and interior of the tap are rust and grit free before fitting the new O ring. It might be worth buying the paper gasket which is sandwiched between the heater tap and heater matrix as there are no guarantees it won't tear when you separate the tap from the matrix. I have a spare gasket and O ring here in the UK but as you are in France anyway, it might be easier to get them from Vehicules Anciens, do an internet search for their website, it should come up.

O ring part number code on their website is: VA6150-RC

Gasket part number code is: VA6150-RC2

 

[Cowhorns]

Brilliant. Thank you very much, Ive ordered the parts and I'll let you know how I get on.

 

[Cowhorns]

Finally managed to get this done. It turned into quite a palaver.....When removing the tap from the rad one of the studs sheared off half way then when trying to unscrew the retaining screw on the tap that sheared off too. First we replaced the retaining screw by drilling a 2mm hole and superglue-ing in piece of 1mm copper cable core with the insulation still on it. The stud was more involved; we took an 8mm bolt, drilled it through, tapped a 5mm thread, rounded off the nut, cut a slot and finally having drilled out the tap fitting as much we dared, ground off the thread on the 8mm bolt. Quicker to buy a rad and tap from a scrap dealer, yes but not as much fun.