Electric Water Pump Initial Warm Up

[JeffW]

My new Stag came with a Davies Craig EWP and (I believe) Kenlowe fan fitted. It has the 8000 series controller. The temperature is set to 85c on the controller, at which the pump is supposed to kick into full speed from what I have read.

However, when I start the car from cold, the 'EWP' symbol on the controller flashes, meaning the pump is in pulse mode as the car heats up. As the car heats up, the Stag temp gauge (Mk1) moves to the Normal two dots position (needle vertical) but the temp on the controller screen doesn't register at all. The Stag gauge then continues to rise dangerously towards H. The EWP does not kick into operation as the temperature is not registering on the controller.

To stop the rise to H, I then have to reset the temperature on the controller to below whatever it is now reading (usually about 60c), which then causes the alarm to go off and the EWP kicks into action as it thinks it is overheating. The temperature on the controller then seems to register up near 90, and as the pump is now operating, the temperature comes back down to normal and the EWP and fan continue to operate properly.

I see in the instructions that the thermostat should be removed. I don't know if this is the case on mine but this behaviour appears to suggest there is a thermostat present when there shouldn't be, or one of the two sensors (Stag one on the head or the DC one in the upper rad hose) is not working correctly.

Any ideas from those who know these EWPs?

Thanks
Jeff

[trunt]

Where is the EWP temp sensor? Is it on the top of the top hose as usually installed?

On the thermostat - it can run with a thermostat (mine does) but it needs to have a couple of holes drilled into it to allow some bleed water through the system to open the thermostat and feed enough to the sensor. Perhaps someone fitted a new one and didn’t provide them?

In the normal install the bypass is blocked so without those holes perhaps the intermittent pump can’t get enough water to the thermostat and maybe the full speed gets enough hot water there to open the thermostat and then it works fine?

Terry

[JeffW]

Where is the EWP temp sensor? Is it on the top of the top hose as usually installed?

On the thermostat - it can run with a thermostat (mine does) but it needs to have a couple of holes drilled into it to allow some bleed water through the system to open the thermostat and feed enough to the sensor. Perhaps someone fitted a new one and didn’t provide them?

In the normal install the bypass is blocked so without those holes perhaps the intermittent pump can’t get enough water to the thermostat and maybe the full speed gets enough hot water there to open the thermostat and then it works fine?

Terry

Hi Terry

Yes, it is installed in the top hose as usually installed.

I did read about drilling holes in thermostats, but as you say, perhaps the previous owner who had this installed did not. I suspect you are right in that the pulse would not get enough water to the thermostat for it to open.

I guess I should just pop the cover off and see what's in the housing. Do you suggest I just remove it if there is a thermostat installed?

Thanks again
Jeff

[StagJonno]

The thermostat has been removed on mine and the DC controller manages warm-up fine (though takes ~3/4 extra mile for normal operating temperature to be achieved).

Sounds like the DC temp sensor may not be operating correctly - my controller (think it's a 8001) constantly shows the temperature in the top hose.

PS - some folk fit 88C thermostats.

[JeffW]

The thermostat has been removed on mine and the DC controller manages warm-up fine (though takes ~3/4 extra mile for normal operating temperature to be achieved).

Sounds like the DC temp sensor may not be operating correctly - my controller (think it's a 8001) constantly shows the temperature in the top hose.

PS - some folk fit 88C thermostats.

Thanks Jonno - do they drill the holes in the 88c thermostats?

For £17 I think I will replace the DC sensor first. Will save a lot of coolant all over the place.

Thanks
Jeff

[KOY 23]

Top hose is not the correct place for pump sensor if a thermostat is fitted, as hose will be cold until ‘stat opens. Drilling holes may help a bit. The proper place is in the transfer housing. Top hose is for fan switch.

[fussydave]

Top hose is not the correct place for pump sensor if a thermostat is fitted, as hose will be cold until ‘stat opens. Drilling holes may help a bit. The proper place is in the transfer housing. Top hose is for fan switch.

Worked fine for me. I reinstated the bypass so the EWP pulsed the coolant around the block until it warmed up and then stat opened and pump ramped up. This helped the engine warm up much quicker. Before refitting the stat the car would take up to 20 miles to fully warm up and in the winter it would take even longer.

[flying farmer]

Personally I would throw the controller away and hard wire the pump through a MK1 ignition ballst resistor fed from an ignition live.

Without the thermostat the heater is next to useless unless you fit a seperate heater circuit pump.

I have 4 engines cooled by Davies Craig pumps. The only one fitted with a controller was a PITA. In really frosty weather even with a thermostat fitted the pump was only on for 30% of the time as the engine never reached operating temperature (this was the Rover V8 in my Toledo). This meant that heater output was so poor the inside of the screen used to ice up while driving even though the temp gauge was reading about one quarter.

Another problem was that when in traffic in the dark with all the lights on, the battery voltage would drop below the critical point where the controller would default to full speed pumping. This would just exacerbate the battery drain problem.
In the end I binned the controller and went the resistor route like my two previous cars (the 4th pump was added later when yet another standard pump died)

By feeding the pump through the resistor it cuts the running voltage to about 8V, slowing the pump, but still provides sufficient cooling even for my high performance engines. I have added a resistor bypass to my TR as it does have over 250bhp to cool and spends lots of time at full throttle on track days.

In the probably 15 years since I fitted my first resistor fed Davies Craig pump I have only ever had one problem. This was caused by mounting the resistor low down on a spare bolt hole on the bottom of the chassis rail on my MK1 Stag. After 3 or 4 years of water splashes from the tyres the resistor corroded and failed resulting in a boil up. Fortunately I had fitted a spare male spade to the pump side of the resistor so was able to plug the supply wire onto this to bypass the resistor. Needles to say I fitted replacement higher up!

[trunt]

I’m running a stat with the Davis Craig because in the winter the coolant did not get up to temperature, and as I have an early manifold without the “foot” didn’t want to reinstate the bypass. It seems to work fine, summer and winter the engine warms up fairly quickly and the heater is OK.
As I live in USA the temps here hit 90-100 in summer and can absolutely go below freezing in the winter so I selected a high flow 82 degree stat and run the controller at 85 in winter and 90 in summer, I reasoned that at 90 in the summer that stat will be wide open and not interfere with the flow.

Neils points are absolutely spot on but I prefer the heatsink run on of fan and pump after ignition off and the over temp warning light to a warm bum! But TBH I only drive in winter occasionally.

[trunt]

Hi Terry

Yes, it is installed in the top hose as usually installed.

I did read about drilling holes in thermostats, but as you say, perhaps the previous owner who had this installed did not. I suspect you are right in that the pulse would not get enough water to the thermostat for it to open.

I guess I should just pop the cover off and see what's in the housing. Do you suggest I just remove it if there is a thermostat installed?

Thanks again
Jeff

The symptoms do seem to point to a thermostat without any holes, yes of course you can take it out but if you drive a lot in the winter as others have said you may find that the coolant will take ages to heat up or as in my case never make it up to the set temperature.

But that’s months away!

[StagJonno]

The EJ Ward specially commissioned pipes work well - the bottom hose to the pump inlet incorporates a T to the heater return. I think 5C was the lowest temp I've run it at and I was happy with the heater performance. Am unlikely to have it out in lower temps as up here, they're pretty active in salting the roads and that is to be avoided.

As I said before, the engine gets up to temp reasonably quickly and, like Terry, the pump & fan run on after switch-off is one of the main reasons I chose EEWP over the belt-driven option.

[StagJonno]

Thanks Jonno - do they drill the holes in the 88c thermostats?

For £17 I think I will replace the DC sensor first. Will save a lot of coolant all over the place.

Thanks
Jeff

I was meaning that, in general, there are folk who like to go for the 88C stat - not that they were necessarily using these with DC EEWPs.

[JeffW]

Thanks all for the responses. A few notes:

- This is an EJ Ward kit, although I do not know if they installed it in the engine. The engine was rebuilt by Wards and sent back to the owner crated. As the engine only has 850 miles on it, I am rather nervous with this setup acting the way it is.

- The heater works perfectly, but it does have the T to the heater return as mentioned by StagJonno

- I don't drive it in winter, too much gritting around here too, so winter heater performance is not really a concern for me.

- Personally I am minded to rip it all out and replace the original water pump and viscous coupling and fan. I don't like complex electrical setups on critical systems like cooling, especially where I don't know who fitted it and wired it up. Not trying to stir up the water pump debate, but I am no flying farmer with the skills like he has to rewire this competently. However, I am also loathe to remove the inlet manifold as I hate that job more than anything.

Some pictures attached of the setup. I guess the first thing to do is determine if there is a thermostat installed.

Thanks again for all the advice.

Jeff

[StagJonno]

If EJ Ward rebuilt the engine off the car, then possible they might have fitted a thermostat. Understand your concerns on reliability but I heard that EJW got their fingers burnt with failures after fitting new standard waterpumps so now will only fit the DC EEWP If you search waterpumps, you'll see tales of woe with poor quality WP gears, sometimes locking up the jackshaft and causing valve damage leading to a full rebuild.

Steve Hill of this forum offers an external belt-driven waterpump kit, which is similarly to the EEWP, mounted low down (generally preferred to reduce damage if coolant is lost) on a Facebook site.

I'd suggest for starters that you check out the thermostat situation and then see if you can become comfortable with what you have.

[JeffW]

If EJ Ward rebuilt the engine off the car, then possible they might have fitted a thermostat. Understand your concerns on reliability but I heard that EJW got their fingers burnt with failures after fitting new standard waterpumps so now will only fit the DC EEWP If you search waterpumps, you'll see tales of woe with poor quality WP gears, sometimes locking up the jackshaft and causing valve damage leading to a full rebuild.

Steve Hill of this forum offers an external belt-driven waterpump kit, which is similarly to the EEWP, mounted low down (generally preferred to reduce damage if coolant is lost) on a Facebook site.

I'd suggest for starters that you check out the thermostat situation and then see if you can become comfortable with what you have.

Thanks Jonno. Not really worried about the reliability of the DC EWP as I know they are good, but am worried if it is installed correctly.

I'll check the thermostat on the the weekend and see what's there.

Thanks
Jeff