Hi all,

I recently completed a full conversion to an electric water pump (EWP) and thermostat delete, using a Davies Craig EWP kit linked below. I chose to install this kit alongside the new Extinct electric fan conversion kit since I wanted to remove the radiator as part of that project. The fan conversion has been fantastic, and has made a huge difference in quieting my engine. Thank you to @Extinct for the extensive support with installing the fan kit.

I went the EWP route after looking at fan controller options for the Extinct kit. I discovered that 8002 Davies Craig controller works for both EWPs and electric fans, and figured I'd go all the way and purchase the full EWP kit which includes the controller. Going with the full DC kit saved me money by not needing separate controllers, not needing to replace my aging thermostat, and not needing to buy a separate coolant temp monitor because this kit comes with one. Plus I already had planned to refresh my coolant lines.

3/16/25 UPDATE : After testing, this setup likely requires an inline thermostat, as the setup otherwise cools too well in certain conditions. This guide also does not include re-routing of the heater return hose, and reservoir hose, which may be critical too. Pending.

This was an advanced project for me, especially since I couldn't find anyone else who had done a full conversion on a D2. This was my first time working on an engine cooling system, so I'm sure there may be things I haven't done quite right. Figuring out everything for the EWP conversion took me over 30 hours, so I'm hoping this guide can serve as a big shortcut and serve as my contribution to the community. Any constructive criticism or simplification ideas are welcome. Follow this guide at your own risk. It may contain errors or omissions. I mostly just wanted to get it written down and posted while I had the motivation.

The basics steps below include: 1) Temporary removal of OEM pump, 2) Cutting off OEM pump impeller blades, 3) modifying upper and lower radiator hose routing, 4) thermostat removal, 5) EWP installation, and 6) EWP controller installation and wiring.


Upsides:

1. MPG Gain (still testing, but I'm hoping for 0.5-1 MPG from the pump alone, 1.5-3 MPG combined with the fans), theoretical power gain at low RPMs
2. Direct monitoring of coolant temperature - but, this is not a replacement for monitoring your engine temperature directly, in my opinion.
3. No need for a thermostat
4. No need to buy a separate fan controller if you install an electric fan like Extinct's kit. The Davies Craig kit controls both the EWP and electric fans (relay still required to trigger fans)
5. If your water pump bearing ever fails, you can simply convert the pulley to an idler.
6. It's kinda neat

Additional Upsides when combined with electric fans:

1. SIGNIFICANTLY quieter engine bay, I couldn't believe how big of a difference this made, even when the fans are on.
2. No thermal soak upon shutdown - Controller runs fans for 2 minutes after shut down, potentially improving long-term engine health

Downsides:

1. Introduces many new points of potential failure
2. Time and effort. The hardest parts were removing the old pump gasket (mine was extremely difficult), and figuring out how to route the new hoses, which I have solved for you.
3. Fan failure is only detectable via temperature increases, not directly from controller. I think the controller can detect pump failure, but I'm not sure of the extent of its capabilities.
4. Reliable, proper electrical connections are critical
5. Unproven reliability or longevity

Unknowns:

1. I haven't measured the time it took the engine to reach operating temp (180-200*F) with the OEM thermostat. If anyone has approximations in 60-70*F weather, I'd appreciate it. I'd like to measure how long it takes with the EWP.

Amazon links below - These are the actual items I used
Tools

1. Metric socket set
2. Impact driver and impact sockets
3. 35mm fan wrench
4. Hose Clamp Pliers - I never thought I'd use a single tool more for one project
5. Angle grinder and disc intended for metal cutting
6. Extra hose clamps
7. Your choice of tools for removing old water pump gasket
8. Wire strippers
9. Heat gun
10. Pipe saw for cutting hoses

Parts List

1. Davies Craig DC-8970 EWP150 Pump and Controller Kit - This is their most powerful pump. Includes pump, controller, temperature probe, probe port, and accessories.
2. 3 x 1.25in hose adapters
3. 1 x 1.25in to 1.5in hose adapters
4. 1 x 6" radiator hose
5. 1 x 1.25in elbow hose
6. 1 x 1.25in to 1.5in elbow hose
7. 1 x 1.25in to 1.5in straight hose reducer
8. 1 x 1.5in straight hose
9. Coolant of your choice - I chose Zerex G05 for longer coolant lifespan compared to green coolant. Feedback welcome.
10. Electrical ring connector - I used this kit
11. 2 x Standard size fuse taps with 5A fuses
12. Solder heat shrink butt connectors
13. 1 x Relay harness with SPST 40A Relay (if adding electric fans)
14. 1 in to 4 out electrical butt terminal (only if using Extinct fan kit)

Instructions:

1. Disconnect battery, removing is a good idea since you'll be working nearby
2. Remove your upper fan shroud
3. Using a fan wrench, carefully remove your clutch fan and set aside
4. Using a socket, loosen the 3 10mm bolts on your water pump
5. Using the belt tensioner pulley and a long wrench, remove your drive line belt and set aside
6. Finish removing the 3 bolts from your water pump, and set aside pulley
7. Drain your coolant into a pan by removing the bottom right 12mm bolt on your water pump
8. Remove the remaining 12mm and 10mm bolts from your water pump
9. Disconnect hoses from pump
10. Disconnect thermostat from hoses
11. Disconnect lower radiator hose
12. Disconnect main "wye" connector from pump - KEEP ALL OTHER HOSES ATTACHED TO WYE
13. Disconnect hoses to coolant reservoir
14. Remove reservoir and set aside
15. Disconnect primary upper radiator hose, both engine-side and radiator-side. Set aside for later.
16. BEFORE attempting the next step - Reference the forums and YouTube for gasket removal procedures for aluminum blocks. This is a step where a mistake can be costly.
17. COMLPEX STEP - Carefully remove the old gasket from your pump and engine cover. Care must be taken not to damage the aluminum. I found this process to be extremely difficult, and ended up needing to use a Scotch Brite Roloc (White) wheel and adapter, onto an impact driver. This took me 3 hours. Hopefully yours is way easier to remove.
18. With an angle grinder or other tool, carefully cut off the water pump's impeller blades, and clean out as much of the metal dust and debris as possible
19. Replace gasket and reinstall pump using your preferred method - See YouTube and other online guides
20. BEFORE RECONNECTING HOSES - remove existing clamp from ONLY the U-shaped hose
21. Spin U-shaped hose 45 degrees clockwise so it ends up pointing towards the wheel well. This results in the tube pointing downwards at a better angle for attachment to the pump.
22. Cut 6" hose to 3", and clamp to radiator
23. Add 1.25 to 1.5 diameter hose coupler and attach to radiator hose. Clamp all connections.
24. Add a 1.5" diameter hose to coupler and connect to EWP. Clamp connection.
25. Connect EWP output port to U-shaped hose. Clamp connection.
26. Re-fill reservoir with coolant
27. Bleed system (use official RAVE method)
28. COMPLEX STEPS - Electrical connections
    1. NOTE: Being able to create solid, reliable electrical connections is critical for this project. You'll need wire strippers, tight connections, and heat shrink sealed where possible. There are too many details here to include everything, so please utilize YouTube and ChatGPT.
    2. Place Davies Craig controller and wire loom inside of passenger footwell area temporarily
    3. Remove footwell plastic trim under the glove box
    4. Excluding the ignition wire, fish all electrical lines through the firewall hole just behind the footwell carpet
    5. Using a snake camera or snake tool or other method - Fish the Ignition Wire through to the Cabin Fuse Box.
    6. Follow wiring diagram for Davies Craig EWP
       1. Controller to cabin fuse box
          1. Using a Fuse Tap and 5A fuse, connect Fuse Tap ensuring the output wire is on the positive side, which for LHD vehicles is facing towards the steering wheel. These are NOT reversable!
             1. Use Fuse 26, or any ignition-switched fuse of your choice
             2. You will need to fish
       2. Controller to pump
       3. Controller to ground
       4. Controller to battery positive - DIY connection
          1. Use an M7 or M8 metric bolt, depending on model year, that screws into your positive battery terminal
          2. Wire your controller to the battery using a ring connector
       5. Controller to temp sensor
       6. For electric fan installations - Controller to electric fan trigger wire
          1. Use the Davies Craig instructions included with the kit to add the following:
             1. FOLLOW PROPER PIN INSTRUCTIONS IN THE KIT
             2. Controller fan trigger wire to 40A relay - DIY connection using solder heat shrink butt connectors linked above
             3. 40A relay to battery positive - DIY again
             4. 40A relay to Engine fuse box
                1. Using a Fuse Tap and 5A fuse, connect Fuse Tap ensuring output wire is facing INWARDS towards the engine. These are NOT reversable.
                2. Use Fuse 16, or any always-on fuse of your choice
             5. 40A relay to electric fan trigger wire - DIY again
29. BEFORE STARTING ENGINE
    1. Check all connections, everywhere.
    2. Bleed
    3. Set key to ACCESSORY
    4. Test pump functionality and bleed system again if needed
30. Once you're satisfied, test while engine running, monitor temps.
31. Perform additional road tests as needed.

Thanks and enjoy.

 

Photos - Do not quote reply to this post.



Exposed water pump gasket

Water pump ready to have the impeller cut

Impeller cut off

BEFORE turning U hose

AFTER turning U hose

Upper radiator hose view - Temp sensor not installed. I got rid of the bleed valve pictured.

Footwell firewall hole wiring in progress

View of the running controller in progress

Cabin fuse box with fuse tap

Upper radiator hose view

Extinct fan kit wiring

Battery positive wiring

Engine fuse box with fuse tap

Relay to fan trigger


Radiator to pump

View of pump to U hose

 

pretty cool, can you provide what you figure the cost was?

 

Great write up. Thanks for sharing!

 

Yeah, I'd estimate $550-$600, excluding the cost of coolant. This excludes the cost of the fan conversion portion of the project.

 

Nice job. @CharminULTRA consulted throughout the project. In my opinion the EWP is fuel economy and hp optimal for several reasons:

1. EWP is only going to consume the horsepower needed to maintain temperature, at lower ambients it will should use much less power than factory. At highway speeds where there is lots of airflow pump and fan power consumption should be minimal.
2. EWP should improve cooling at high ambients as it will push much more coolant through engine and radiator, especially at low rpm. Think maximum flow at nominal engine rpm, potentially more flow than factory pump even at redline.
3. EWP with variable speed controller should maintain very consistent temperature.
4. Easier service access.
5. As demonstrated by the flowkooler waterpump, the factory impeller design is less than optimal.

 

Thanks! After a long drive, my set up seems to be too effective. On long descents at 55-60 F ambient, the OBDII engine temp reading drops to 170 F. I even saw the coolant temp reading drop to 160 F. On ascents, it reached 200-205 F.

The OEM setup previously kept the engine at a consistent 195-205 F, even on 85 F days.



My target on the controller was set to 200 F (fans activate at 205 F). I knew this was high for testing but I’m surprised that the engine appears to be way too easy to cool using this set up.

Im thinking maybe I should install a thermostat now. What do you think?

 

What is the minimum speed on the pump? It may be too high. D2 with no thermostat runs about 140, so it is controlling temp somewhat.

 

I think you have an admiral project on your hands, but there may be a couple of concepts that you haven't quite grasped, maybe? It's rare to have a project like this work perfectly on the first attempt, because of the number of variables involved.

If there is nothing to reduce the coolant flow to zero, then you'll get heat transfer all the time. The coolant can circulate from thermal convection anyway, so there needs to be some kind of block or valve - otherwise, once circulation has started, you have no way to stop it. It's a sealed system, so there is no other opposing force to the siphoning around the system - gravity does not apply in a sealed, circular system.

It's a bit like the holes people drill in thermostats and don't fit a jiggle pin - the coolant has a tiny flow continually and the engine runs cooler than ideal. The Jiggle pin blocks the hole anytime the mechanical pump is running, so the flow is blocked. Without it, a lot of heat is lost at undesirable times. A kit for our old BMW has a thermostat like this. Not only was the hole not required for bleeding, but it meant temps plummeted on long downhill grades, when the engine was producing so heat. Around town, it meant the engine took so long to get to operating temp on short trips, that fuel consumption increased about 15%! Blocking the hole solved it 100%, back to how it was before.

There is a reason why modern manufacturers of vehicles often still have mechincal pumps, but often have a regulating valve bult in. The mechanical pump hardly uses any power - the pump is not a "pump", it creates basically zero pressure, just flow. It's a "circulator" really. Thos that use electric only, still usually have the same basic flow designs, but use the electric pumps for constant circulation during stop/start technology, etc. They often use them to create flow when a mechanical pump won't help, rather than to not circulate coolant.

Or my mid 2000's VW, where it is used after shutting down the engine, to circulate coolant and run the fans on low to reduce the peaking of temps that occur after the engine is shutdown (this was pretty common on some 80's euro performace cars too)

Modern designs have the pump moving coolant continually through the block for even warming and avoid localised micro-boiling in hot spots. The regulator (rather than a mechanical thermostat) is used to divert the pumps output: either returning it to the block cirulation path, or circulating through the radiator. Most setups can force the coolant 100% either way - like the original Disco 2 setup can, when it's working correctly: As this video expalins very well, although it uses "generic" temperatures:


Modern pumps have the regulator built in, so there is minimal heat loss through the exposed hoses and it can be kept more within the block.

What may make more sense, is to have the mechanical pump circulating through the engine continually (which incidentally provides flow to the cabin heaters), with the back of the thermostat in the moving coolant path (to keep even regulation, like the D2 setup), then have the electric pump kick in, only to force coolant through the radiator half of the circuit - then you aren't reliying on the rover pumps limited capacity in this regard. Then the full capacity of the electric pump is moving hot coolant into the radiator, allowing it to cool and returning the lower temp coolant to the thermostat, wheich can then better regulate the temperature, by mixing the block circulation path with the radiator return - just your capacity for this process would be much higher.

If the Rover themostat is working correctly, the engine coolant is directed (basically) 100% through the radiator circuit when it 's getting too hot, BUT the pumps capacity is somewhat marginal for the task. The concept of this process is also explained well in that video at 5:08, then 5:28. This has been used in most modern cooling designs, at least since about when the D2 introduced it - it was certainly common in the 90's.

Since relliable D2 thermostats seem to be hard to get now, it may be worth looking into the ford/jaguar bypass setup, that has a range of thermostats available and also worked correctly, bu forcing the engine block circulation to close entirely, when temps climb.

A bit of tweaking, and you may have the ultimate cooling setup/

 

This makes sense, thanks so much for the info and video. My general assumption previously was that the DC controller was designed to replace a t-stat, which is how it's marketed. It seems like their programming design doesn't really achieve this goal for this application, because it doesn't slow down the pump enough when the engine temp drops too far. Obviously, as you pointed out I have some gaps in my understanding so maybe I'm not reading their documentation quite right.

If I understand your post correctly, are you suggesting returning to the OEM flow setup and moving the EWP location? What do you think about just adding a 195*F inline t-stat? This would be a pretty easy addition to the existing design. I noticed Davies Craig mentions in their documentation that a thermostat may need to be used in cooler climates, with 2 holes drilled into it.

I think at this rate, I'm either willing to add an inline t-stat, or go back to OEM setup entirely since I had consistent 195-205 temps with OEM. The fans have been the bigger value-add anyway.