Flowkooler coolant pump

The engine cooling system on my 2004 D2 works about as good as a D2 can work, but I'm still not satisfied. I have done the inline thermostat conversion (with a 180* Stant), added a transmission cooler from a 2003 as an engine oil cooler, and put in a rebuilt 4.6L with flanged liners. New radiator, new pump, new everything. Everything works great, the engine runs and idles smooth, but it's still not enough cooling capacity. In the dry summer weather out west here, especially in the mountains, engine temperatures can still get higher than I'd like. Especially with the air conditioner running. Once the ambient temperature gets above 90 at low humidity, I really get unhappy with how the cooling system works.

I've looked at all the options, and while an $800 radiator might improve things, I'm not sure that's really the solution. I've noticed that at idle speed, a change of a couple hundred RPM really makes a big difference in cooling capacity--I think the OEM pump is extremely inefficient at low speeds. When I turn the A/C on in hot and dry weather, the engine temperature will climb by ten degrees Fahrenheit just driving slowly around town. So I looked into getting a better water pump.

In the end, I looked at Flowkooler. I have a Flowkooler water pump in my Jeep 4.0L, and it works great. Flowkooler has a good reputation among the hot rod crowd, as well as the Jeep crowd, for making a reliable pump that can help keep engine temperatures more stable at low RPMs. What they do is copy OEM pump castings, and fit them with good bearings and a proper machined aluminum impeller that has more blades than OEM pumps usually do, a better shape to the blades, and a shroud to prevent cavitation. The end result is a pump that has significantly more pressure (and flow) from idle up through about 3000RPM, at which point the blades stall and pressure does not exceed the OEM pump pressure at full speed. So you get more flow at lower engine speeds where you need it, while not exceeding safe operating pressures for the cooling system. Having held one in my hands before, I can say they're a really well-built pump, and a nice piece of machining work.

The Jeep 4.0L is a tough engine, but it definitely gets hot. Adding the Flowkooler in mine made a big difference in driving around town at low RPMs, and in slow-speed hill climbs. The Jeep engine temperature actually drops a little when I get on the accelerator and RPMs come up between 1500 and 2000 RPM, and it stays in about a 10-degree range no matter what I'm doing, no matter the weather. I've noticed that my D2 temperature seems to increase the worst when I'm giving it gas in the 2000 to 2600 RPM range, and I would love to give it the same stability my Jeep has!

I talked to Lee at Flowkooler, and he has agreed to develop a high-flow pump for the 3.9L, 4.0L, and 4.6L Rover V8, if he can get orders for 10 of them. These first 10 will have about $80 added to the price to cover the development cost. As they sell more past those ten, the development cost will be rebated back to the first 10 customers. They're asking $249 for the special order, which I think works out to $169 for the pump, plus development costs.

I've already placed my order, and I hope a few others will step up to the plate on this. It's worth it just to have another source for a good-quality pump, and I'd really love to see these Rover V8s able to run cool under a wider range of conditions.
The link is here: https://www.flowkoolerwaterpumps.co...nd Rover 3.9L, 4.0L or 4.6L/product_info.html

I'm adding this in case you're wondering why the Flowkooler pumps improve engine cooling.

More flow, as long as you don't reduce the system pressure, will always mean more cooling. The more trips the coolant takes through the system per minute, the more heat it will move. I've heard people say more flow makes things worse, that coolant needs sufficient time in the radiator to get cooled down, but that's wrong.

Heat flows from hot things to cold things. The hotter the hot thing is, and the colder the cold thing is, the faster the heat flows. All other things being equal (meaning, if you aren't increasing flow by reducing back pressure, like removing the thermostat or putting in a high-flow radiator), as flow increases the coolant temperature will increase less as it goes through the engine, and its temperature will decrease less as it goes through the radiator and *that is a good thing*. That means that all the way through the engine, the coolant is absorbing more heat, because there is a greater temperature difference between the block and the coolant. All the way through the radiator, the coolant is shedding more heat, because the temperature difference between the coolant and the radiator fins is greater. And it's making more trips in the same amount of time through the circuit, so the overall heat rejection is higher. The end result is a more stable engine temperature.

If you don't believe me, get your engine good and warm, and then coast down a long hill with your foot off the accelerator, and watch the temperature. The increased engine RPM gets you more flow through the water pump. It's just like idling with a high-flow water pump, and it does a great job of decreasing the engine temperature. That's what more flow does for your engine.

Humidity helps quite a bit. I'm looking at hot and dry weather, and with both front and rear A/C on, it gets up to the low 200's. If I pull up a long hill with ambient temperatures above 100F, it will hit 215 or even 220.

The other thing is that engine temperatures are reasonable only if everything is in perfect working order. I'd prefer to have more cooling capacity so that it doesn't go to heck just because of a dirty fuel injector.

Oh, and by the way, the question about commissions is an asshole move. If they develop a water pump, I get to buy one. That's all. I'm hoping other people want one too, because I can't fund the entire $800 development cost. I'm not getting paid.

mbrummal,

I'm sure a bigger radiator would improve things, but a high-flow water pump is quite a bit cheaper. And this radiator and fan really ought to be big enough to keep the coolant temp under control just driving around town with the A/C on.

JohnB said:

I have thought about just going electric water pump and just grind off the impellor on the water pump. Would be nice to run the water through after shut down to avoid heat sync.

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I looked into that, too. If you buy a pump and controller that can actually do the job, it's at least as expensive as getting a better radiator. The Davies-Craig pumps won't cut it. A high-flow mechanical pump is a better option in my opinion, if we can get somebody to make one.

roverover said:

he needs to get his sorry ass out here and sell these to get his numbers up not ask the first 10 buyers to invest in his business with no return on their investment

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You're welcome to ask. If you can get a better deal, that'd be great. If you use the Flowkooler sales e-mail, he'll answer. Personally, given the cost of the other options, I don't see a problem with this deal. But that's just my view.