Davies-Craig EWP issues

[papak]

Looking for others familiar with the Davies-Craig EWP controller (the earlier style, Model 8020). Mine has been acting strangely the last few months. It self-tests normally and follows the programmed profile until I accelerate. At that point, all of the indicator lights illuminate and both the water pump and fan activate. This lasts until I drop the revs below 3000, then all is back to normal.

 

The specifications state that the voltage supply range is 11.5 -15vdc. My little alternator (40 amp, internally regulated) produces 14.5v when at speed (>2000 rpm). I have verified this with an external tester. It sure seems like a voltage related problem but it would have to reside in the mother board, I presume. I have traced and tested every wire and connection in the system with no luck so far. The coolant temp probe is a new Ford unit.

 

This leads to the basic problem, an inability to get the engine up to normal operating temp, even after an extended drive. Yesterday it was in the 60s and all I could get was 130 on the oil and 140-150 on the coolant after a 30 minute spirited drive.

 

Any productive suggestions would be greatly appreciated.

[Dave W]

Replace or pull the thermostat and check the temp which it opens at with a pot off hot water on the stove. I had the same problem even after installing a 92C thermostat, but I'm dealing with lower temps. I have a large rad and at the time I did not have a thermal by-pass for the oil cooler. After adding a block off plate in front of the oil cooler, warm up time was cut to the 10-15 minute range. I now have a Mocal thermo by-pass on the oil cooler, which works great. Dave W

[papak]

As you can see in the attached photo, I have modified the cooling system by removing the internal water pump and eliminating the thermostat (as per the D-C instructions). By utilizing the D-C EWP controller, the thermostat value is set in the controller and it cycles the electric water pump and cooling fan (according to an internal program) as necessary to maintain the selected temperature. It originally worked quite well but more recently, it has become extremely sensitive to acceleration it seems. Aaaarrgh! I never presumed that I would need an oil cooler but I could certainly add one if necessary.

 

 

 

 

 

 

[papak]

I finally switched over to the digital EWP/fan controller (model 18001, a very nice piece of engineering)) and ran into a somewhat different behavior. I observed that after reaching 100F coolant temp, the fan kicked in continuously. It turns out that this was entirely coincidental. I contacted Davies-Craig and John Benson, the Sales Mgr., responded promptly. Apparently, if a coolant temp of 40C/104F is not achieved by the 5 minute mark, the fan defaults to full speed. While the pump runs at various speeds, the fan is simply on/off. I guess that the engineering assumption is that if the low temp situation is due to a sensor failure, this would more readily protect the engine. The solution is to turn off the engine and restart it. This restarts the 5 minute internal timer once again. The alternative is to reinstall the thermostat with 2-3 5mm holes drilled in the perimeter as a flow restrictor.

 

The installation instructions are to remove the thermostat in the first place. I will ask John to add the information about the 5 minute time/temp constraint to the FAQs on their website. Now I should be able to get the engine up to normal operating temperature so that we can finish the tuning.

Edited January 16, 2020 by papak