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Gregte 07-20-2008 07:41 PM

Electric water pump
Just wondering if the belt driven water pump is ever replaced with an electric water pump?

It would seem that the only time the water pump needs to actually pump coolant would be when the engine's thermostat opens. This happens only periodically and not real frequently in cooler weather. The belt driven pump is doing work all the time whereas an electric pump would only need to do work when needed.

Or maybe the belt driven pump is doing very little work when the t-stat is not open and thus no coolant is flowing.

Daox 07-20-2008 08:48 PM

The pump really needs to be going nearly all the time to eliminate any hot spots that develop.

dremd 07-21-2008 12:13 AM

Well; you could run a controller on an electric water pump; and get away with running it much slower most of the time. Payback time? Maybe.

Duffman 07-21-2008 12:52 AM

The advantage of an electric pump would be that the pump doesnt drag more at higher RPM and can be held in the sweet spot constantly.

Gregte 07-21-2008 01:07 AM

Another thing that I had forgot about... the pump needs to be running continuously whenever you are using the heater.

Thanks to all for the input.

Tango Charlie 07-21-2008 09:37 AM

I think most thermostats have a small hole in them so they still circulate a small amount of coolant when closed. At least the thermostats that I've seen.

MazdaMatt 07-21-2008 09:45 AM

I had some overheating problems last weekend (tstat crapped out) and my friend/mechanic explained the cooling system to me. There is apparently a bypass for the rad so the water pump is always circulating coolant within the engine. When the coolant gets too hot, the tstat opens and it starts also coursing through the rad to cool it. You can't run without any water going through or your head would probably warp.

I know that racers use electric water pumps because they push the crap out of their engines, then have to turn them off while blistering hot. They run the water pump for a while with the car off to make sure it cools evenly and doesn't warp anything.

larryrose11 07-21-2008 01:09 PM

Hey guys,
First of all, I wouldn't undertake something like this if you are not comfortable programming a micro computer of some sort, like an Motorola HC11.
Your effots could be put in a better place, like switching over to a manual rack and pinion steering, or plug in battery w/ alternator field kill switch.

I know a bit about electric water pumps. They make sense, mostly on the HEV's I work on for my job. They can run at optimum speeds, instead of just engine speed. Typically coolant pumps on gasoline ICEs actually rely on cavation to limit pump flow!! in order to control e-pumps well, you need to know where you water temp sensor is, and the transfer function for the sensor. You set some minimum flow, say about 0.1 gpm. This will help the engine warm up much faster. There needs to be a target engine coolant temp, say 190F, but below the threshold for radiator fan operation. Use these as your bounds and tune a PID to run a small brushed motor controller that has a 0-5V input.

So here is the non-propriety data: The real benefit to using a E-pump is the elimination of the belt all together. Most modern HEV's already have e-power steering and e-Air Cond. In an HEV, the alternator is redundant, and not present, that leaves the water pump on the belt. The belt, all by itself uses 2-3 HP with no load on it, but that load is pretty constant and doesn't change. Switching to an e-pump allows you to shed that load.

ATaylorRacing 07-22-2008 06:52 PM

To gain more power out of the first car I drag raced I made a electric water pump set up. The car was a 81 Horizon and I bought an electric water pump called a "Water Guppy" that was used to circulate water in bass fishing boats. I had the water pump off of my car (due to bad leaks) and found that the thermostat housing had two bolts that lined up with two where the pump was. I simply bolted on an extra thermostat housing in place of the pump and then put the electric one in line with some longer radiator hose. I ran the pump with a simple on off switch in the car and in hot weather it worked like a dream. I never checked for gas mileage. A trick that a lot of drag racers use is to cut off every other fin inside the water pump. They have less drag, more power, more miles per gallon, and adequate cooling.

ATaylorRacing 07-22-2008 06:55 PM


Originally Posted by Tango Charlie (Post 45978)
I think most thermostats have a small hole in them so they still circulate a small amount of coolant when closed. At least the thermostats that I've seen.

Most of the older cars did not have that feature. I know that the first one I saw was on my 94 Plymouth Sundance Duster....reason for it was to not have as many head gasket failures due to the big temp differences of the water coming in when the thermostat opened up. Since 81 I used to always drill a couple or three 1/8" holes in mine.

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