Cooling conundrum

[e2e]

Thanks for the replies  Huw & Javad
1: I had a fiddle with the water bottle level sensor and the autocheck has
gone away, so that at least was a coincidence.
2: I have some more thoughts on the whole issue.
I have installed the electric pump on to the bottom of the cooling circuit
where the "u" hose goes from the bottom of the radiator to the thermostat
housing (now without thermostat).I assume that the standard flow is out the
top of the head and into the bottom of the block.
This car has never had it's after-run pump fitted so my thinking is that in
its stock configuration and with the water cool the (original) water pump
would pump water out the top of the motor said water would then take a
detour via the small bypass(after-run) hose and both around the heater as
well as back to the other side of the (closed) thermostat. As the water gets
hot the thermostat allows progressively more water through the radiator,
upon which only after natural airflow can't do the job then the fan should
kick in to boost cooling.
So I figure to move the electric pump up to the top hose position and to
replace the thermostat. I am unsure wether to keep the electronic temp
controller or to hard wire the pump to just go full bore. I will be in touch
with Davies-Craig to get an answer and let you know.
3: I still believe that the fan should be set to come on only as the last
(hottest) step in the chain.
4: After-run can be achieved either via a turbo timer or can I use the
existing wiring for the original after-run pump is that a temperature or
time delay controlled circuit?
5: What the heck do all those sensors on the top hose housing do and the one
on the head just in front of it do
>> 1990 200tqa 1b motor (10v turbo)
>> Hi I've just fitted an electric water pump to the car which involves milling
>> off the impeller from the standard water pump and removing the thermostat.
>> The new pump has a probe which I have inserted into the top hose by the
>> head, this controls the speed that the water is pumped around the motor via
>> a temperature adjustable controller.
>
> uh oh... I have no idea what I'm talking about, but that sounds like a
> *terrible* idea.  You need that coolant to keep circulating or you'll
> get hot spots in the head, etc.  I think the "real" engine folks will
> back me up on that.
>
>> I have a few concerns.
>>  The fan is going far too readily and is over cooling the water in the
>> radiator which makes said pump go too slowly and therefore the heater is now
>> terrible. Where is the sensor for the fan. I believe I need to change it to
>> kick in at a temperature above the max I set for the pump controller.
>
> It all sounds scary to me.  You should run your pump at a steady speed
> (with maybe an "overdrive" speed if you can control it effectively), and
> let coolant in to the radiator with a thermostat - this controls the
> engine's operating temperature.
>
> The fan sender is usually in the bottom of the radiator.
>
>> Is the current slow pumping likely to cook up the turbo.
>> What would the optimum temp be for this motor.
>
> 87 C I think, at least that's when the thermostat opens.
>
>> The dash warning is flashing at me while the analogue gauge is reading fine
>> (80 deg C).  This can be either water level or temperature, am I assuming
>> correctly that the level is monitored solely off the bottom of the filler
>> bottle does disconnecting this bypass it or do I need to close that circuit.
>> The temp warning is which sensor and  what parameters trigger it off?
>> The warning comes on within 30 seconds of starting the car hot or cold.
>
> Well... I suppose if the *lowest* speed your pump will run at is enough
> to avoid hot spots then the concept is reasonable.  But ditching the
> thermostat sounds all wrong.  You don't want to pump cool radiator water
> through a cold engine, for instance, and running the pump slow enough to
> achieve that sounds scary... but maybe you know better what you are
> doing than I, too.
>
> the coolant level only runs off the sender in the expansion tank, yes.
>
> the temp gauge sender ought to be in that multi function sender on the
> radiator hose neck... the one that always goes bad.
>
> The overtemp warning I'm not sure about on your car...

--
Sam Clarkson