I vote for trying a T-stat.

 

I didn't go back and read your OP. Did their website or documentation specifically discuss a D2? If not, (or even if so) are you sure you have the hose routing correct? i.e., is the pump in the right place in the system? If they weren't specific instructions for our trucks, are you sure you interpreted their advice correctly? Have you drawn out the coolant flow in your arrangement? How does it compare to the diagram in RAVE? If you have failed to simply replace the stock pump with the EWP, and instead changed to flow routing, that could be your issue. I'd confirm all of that before adding a tstat. If you have a problem, you would still have a problem after adding a tstat. From what you've said you might still need one, but don't keep chasing a theoretical problem while missing the real problem.

 

Good questions. It's not a vehicle specific pump. Yes, I did follow the Davies Craig documentation and recommendations, which included disabling the OEM pump, removing the thermostat, and placing the EWP at the radiator outlet. I disabled the OEM pump by cutting off the impeller blades.

As far as flow, there is no longer a radiator bypass. I removed the T joint at the engine exit, so that hot coolant goes straight to the radiator instead of having the potential routing to the thermostat. You can see this in photo 6 above. I removed the thermostat, as well.

So basically coolant goes to the radiator no matter what, which is what the EWP is designed for.

I have a 180* inline t-stat on hand, which I'm going to try installing to see how that changes things.

 

Oh, I see what you mean now. Yes, I may have reversed the heater core flow. Davies Craig emailed me back and pointed out the likely heater flow reversal, plus the D2's U-hose is also problematic for creating an airlock. Crap.

May have to engineer a solution to that...TBD.

 

I think you will be fine with the thermostat. If you lived in a hotter climate the system would be a very big improvement in the cooling, suspect you may see a big improvement in temperature performance pulling a grade in the summer.

 

Just the fact they suggest holes in the thermostat, puts me off them - it defeates the purpose of the thermostat, by a percentage... it's the same as having a thermostat that doesn't close correctly, which leads to engines running under temp.

You could use the standard pump to circulate as normal, and use the EWP to force feed coolant from the radiator, when the engine gets hotter. You can't really have no circulation though the block, as coolant near the exhaust ports and combustion chamber needs to absorb far more heat than the coolant at the bottom of the cylinders (for example). Circulating it helps keep it even and warm up the engine more evenly. The coolant temps inside the heads could skyrocket, while the temp sensor location could remain cooler, with no circulation. Circulation is pretty standard practice, even on vehicles trying to meet ridiculous emmisions standards, that compromise long term reliability, for better emmission ratings.

Its really the full force through the radiator that's required to overcome/prevent a hot engine (as long as the radiator has enough cooling capacity).

You could stick with the OEM flow setup and add the EWP into the radiator line, to suck cooled coolant, from the radiator - that's the biggest issue with the OEM setup - the flow through the radiator is limited, either because the pump don't circulate enough coolant at low RPM's in particular, or the OEM thermostat isn't opening all the way, to block the bypass return port and force full flow from the pump, to be sucked from the radiator. Whether it pumped from or too the radiator shouldn't matter, though the pump is probably more reliable on the cooler side.

There are other options for a thermostat housing with full bypass too, often in aluinium housings too. I know BMW and similar were using them in the 70's without issue, there must be newer, more available options too. That's what I'd go for.

 

Yes i see this and follow

 

I appreciate the suggestions, unfortunately sticking with the OEM setup plus EWP wouldn't be possible, in my opinion, because there's not enough space in the engine bay.

Holes in the physical thermostat actually achieves this goal, in my specific scenario where I'm going to try using an inline thermostat. The Davies Craig controller already acts as a thermostat (see image below), and if you had no holes in the physical INLINE thermostat, you'd have zero flow through the entire system. My system currently runs under temp, so something needs to be done to slow the flow below operating temperature, without stopping flow entirely.

For a traditional loop system...you're right, I don't quite know why they'd want holes, but again the DC controller becomes a thermostat in that set up anyway.

 

Happy to report that installing the Inline Thermostat 180F made a big difference! The engine reaches temperature in about 5-10 minutes rather than 30 minutes. The only major downside so far is that I no longer have a bleed port and had to unclamp hoses to bleed.

 

Usually bleeding not needed with inline thermostat, you can turn pump on full spped before thermostat opens.