Electric Water pump - Davies Craig EWP

[TERRA Operative]

Can you install a lower temp thermostat (maybe 85 deg or so) with the hole drilled in it?
That way it will let the engine warm up when it's cold, but when you get to the operating temp when the EWP does it's thing, the thermostat is opened already and not interfering.

[carvesdodo]

Originally Posted by Nakkas

The EWP has been working well in the 45 degree temps we had during the Hot months. Now that the temps have plumeted to the mid 20's, things are not normal. It is difficult to get the engine temps to maintain the 95 deg that is set on the controller. When I am at a standstill, it will sit on 95 deg. When I start moving the coolant temp drops. This means the radiator is working too well, or the 115 Lt/Min pump may be too large, flowing too much water. There is a 80 Lt/min option. I spoke to John at Davies, Craig and he suggested putting the Thermostat back in and drill a 6mm hole on the Thermostat. This will restrict the flow slightly at colder temps until the temp reaches 95 deg. I will try this on the weekend and post the result. At least the engine has never risen above the 105 deg mark, which it used to before. With the engine running cooler, the mixture will be richer and I get a bit more performance from her/him. (haven't worked out a gender yet)

Its not that the radiator is working too well ... Its because you have 20'+ drops in windchill factors ...

A radiator provides cooling dependant on airflow quantity and ambient temps ... and radiator outlet coolant temps vary accordingly to the highs and lows those two factors may be at ... at any given time.

.... And the thermostat will restrict the flow of cooler liquid if thats what being provided - by the radiator due to weather/driving conditions.

I.E. ....

Presuming the the radiator inlet temp should always be at approx 100' ... because thats what coming out of the engine as controlled by the thermostat......

The radiator outlet temps are all over the place by comparison .... which is why electric fans should be triggered by a bottom hose temp ... and Im guessing the EWP would be better off that way too.


A radiator provides the cooling ... If its a decent radiator ....

The thermostat keeps the engine at a predetermined minimum "hot" temp.

A waterpump just shunts liquid around the cooling circuit ... It doesnt provide cooling. A stock waterpump varies the flow rate as per the needs of the engine ... as it spins in synch with the revs.

Bodgy flow rates ... or fixed liters per minute flow rates ... can mean too little or too much flow ... with various results.


IMHO ... For the electric pump to be fully effective without using a thermostat ...

It needs to be sensing inputs from;

Radiator inlet temps
Radiator outlet temps
Some front and rear engine temps

........ and making flow adjustments similiar to the way the computer controls the fuel injectors.

Makes a bloody complicated item out of something that only needs move liquid from point A to point B tho.


Keep the info coming .... the things have potential.

Some comparison, summer dash gauge temps ... with and without thermostat would have been interesting .... only a coupla months to go ..

[Nakkas]

The radiator outlet temps are all over the place by comparison .... which is why electric fans should be triggered by a bottom hose temp ... and Im guessing the EWP would be better off that way too

I don't quite agree here because as the water temp around the engine rises the bottom hose temp sensor and therefore the EWP would stay low. It would not sense that the engine temp is rising because the water is not being circulated. What is happening now is when the temp around the engine rises, the EWP will flow cold water to the engine, the sensor sensors (?) this because the water is cold and the guages show a lower temp and EWP stops. I would like to see the pump always circulating but at a slower, constant speed until the engine temp is at operating temp. I think the Thermostat idea will work better as this is what I had in at the start when I installed the EWP.

Its not that the radiator is working too well ... Its because you have 20'+ drops in windchill factors ...

I agree here. The radiator temps were warmer on hot days and does not have such an effect because the engine inlet temps were higher. With the lower inlet temps because of the lower ambient temps, it is more noticable.

[CRUSHU]

The pump controller controls the speed of water thru the engine, ensuring it isn't too fast or slow.

I wouldn't count on fuel savings with synthetic oil, as it will be negated by your worn engine from running crap oil.

[carvesdodo]

Originally Posted by carvesdodo

Presuming the the radiator inlet temp should always be at approx 100' ... because thats what coming out of the engine as controlled by the thermostat......

The radiator outlet temps are all over the place by comparison .... which is why electric fans should be triggered by a bottom hose temp ... and Im guessing the EWP would be better off that way too.

Originally Posted by Nakkas

I don't quite agree here because as the water temp around the engine rises the bottom hose temp sensor and therefore the EWP would stay low. It would not sense that the engine temp is rising because the water is not being circulated. What is happening now is when the temp around the engine rises, the EWP will flow cold water to the engine, the sensor sensors (?) this because the water is cold and the guages show a lower temp and EWP stops. I would like to see the pump always circulating but at a slower, constant speed until the engine temp is at operating temp. I think the Thermostat idea will work better as this is what I had in at the start when I installed the EWP.

I'll try to put it differently ....

The bottom hose temp varies depending on a bunch of factors.

Normally ... If the top hose temp is Temp "A" e.g. 100' ... then the bottom hose temp will be "B" e.g. 80'
( rounded off numbers for demo )

If its hot weather then the bottom hose temp will be "C" and higher than "B" because of ambient temp.

If its hot weather, and the engine is working hard, and the thermostat is wide open, then the top hose temp will be "D"

In this case .. the bottom hose temp will be "C" plus the additional temp of .... "D" minus "A".


If electric fans always come on at about the bottom hose temp of "B" .... that will best facilitate maintaining the top hose temp of "A" .... rather than hoping the little fan helps after activating at temps of "D+".

If that wasnt the case .... It would make the electric fan over-ride switch a futile modification.

Its how the fanclutch works too .... It activates at a certain temp defined by the radiator air flow temp hitting its sensor spring ... NOT when the temp gauge sensor hits a certain high point.

As for the EWP ....

With only two flow speeds ... it cant vary flow quantity as well as a properly functioning thermostat .... Its either On or Off.

I can see it being made to work OK if the thermostat is fitted .... but relying on it to provide flow and temp control with only two flow speeds and its On/Off operation might be a bit much for all driving circumstances.

Like most extreme sports, orientated car mods ... some things are only suitable for controlled conditions or short dragstrip runs.

[Nakkas]

Originally Posted by Nakkas

Its not using extra fuel. Quite the opposite. Sitting on 80 kph, it's using 9-10 l/100 km. The EWP does not run all the time



The pump only runs constantly when the temp goes above the set temp, which is 95 deg.
The controller takes the place of the thermostat.

There isn't just 2 speeds. The speed of the pump varies once it reaches -5 deg of the set temp. There is 2 speeds at a reduced voltage below this. My preference is for a constant reduced low speed, around maybe 3-4 volts during warm up. That way the temps in the hoses and the radiator are more constant and not entering the engine at a much lower temp.

[carvesdodo]

Originally Posted by Nakkas

There isn't just 2 speeds. The speed of the pump varies once it reaches -5 deg of the set temp. There is 2 speeds at a reduced voltage below this.

OK ... If it has a variable speed motor ... that will help in attempting to maintain a set temp.

Originally Posted by Nakkas

My preference is for a constant reduced low speed, around maybe 3-4 volts during warm up. That way the temps in the hoses and the radiator are more constant and not entering the engine at a much lower temp.

You wont get a constant temp in all of the cooling system unless the windchill factor on the radiator (airflow & ambient) and the workload on the engine ... is constant.

And those three things are constantly changing .... On their own - each factor doesnt create much of an issue ... but when they are combined ... its a different matter.

Thats the whole problem with the XJs cooling system ..... The stock design is such that it should only be driven on a flat road at 90kph on a 20' day .... Even the FSM acknowledges that ... by referring to hills, stop/start traffic, and temps over 30'c as "abnormal" driving conditions - that cause overheating.

IMHO .... Someone in the chrysler design team thought everything was constant .... and forgot that vehicles get used in lots of different places ... in lots of different ways ...


Best you can hope for is a constant temp at the gauge sensor .... and that requires a cooling system with a radiator that provides sufficient cooled liquid to allow the thermostat to do its job ... Of mixing the liquid to maintain a temp at the gauge sensor - similiar to the stated thermostat temp - in all conditions.

If the EWP can be tied into that process ... so much the better.