DIY electric water pump - on the cheap

[Daox]

Originally Posted by sqidd

So you want to run the water around before you start the motor? Novel idea. Pre-heat the block, then circulate the water to the trans and warm that up too. Then start the car. I like that.

You got it. When the block heater is active, I'll kick the pump on at a very low speed just to move the heat around.

You linked a pic a few pages back but i'm not sure if that is what you decided you were going with. How are you planning on heating the trans with the water again? What sort of heat exchanger setup?

That is in another thread of mine: http://ecomodder.com/forum/showthrea...ant-29872.html

I really don't have it all figured out yet. I'm just kicking the idea around and getting some ideas from others to refine what'll eventually be done.

Also a few questions regarding another idea I was thinking of:

Does the OEM cooling system use a internal bypass when warming up? Or a external bypass. Or no bypass at all? Do you have any pics of how the cooling system runs and where the T-stat is at?

The radiator is plumbed in parallel with the rest of the system. So, when the thermostat is closed the water bypasses it and just circulates through the block and head. When it opens up, the coolant flows in parallel through both. As far as I know, this is how pretty much all cooling systems work. Here is a cooling diagram for the car.

[sqidd]

Originally Posted by Daox

That is in another thread of mine: http://ecomodder.com/forum/showthrea...ant-29872.html

I really don't have it all figured out yet. I'm just kicking the idea around and getting some ideas from others to refine what'll eventually be done.

OK, that's where I saw that pic. I'm not all warm and fuzzy about how to transfer the heat from the hot water to the trans. I'm going to need to think about that for a while. I'm not thinking of anything that will have enough surface area to transfer much heat. No more than the block will transfer into the trans case already.

You could run a water/oil heat exchanger and pump the trans fluid through one way and the coolant through the other. But WOW, that would be some fiddling around there!

How about a second block heater in the trans case? That would be super easy.

The radiator is plumbed in parallel with the rest of the system. So, when the thermostat is closed the water bypasses it and just circulates through the block and head. When it opens up, the coolant flows in parallel through both. As far as I know, this is how pretty much all cooling systems work. Here is a cooling diagram for the car.

Are you sure? All the systems I have had my hands on have a "double acting" T-stat. When the T-stat is closed the water bypasses the radiator and just goes right back into the motor. When the T-stat is open there is another "plunger" on the end of it that closes off the bypass and re-direct the water through the radiator.

Like this:

[oil pan 4]

Small engines don't typically use double acting thermostats. My diesel has one.
Even small block chevys do not have them.

Originally Posted by sqidd

So you want to run the water around before you start the motor? Novel idea. Pre-heat the block, then circulate the water to the trans and warm that up too. Then start the car. I like that.

Yeah.
http://ecomodder.com/forum/showthrea...mer-23893.html

Everything I have read recommends not starting diesel engines below 20'C and 50'C is recommended.

[sqidd]

Originally Posted by oil pan 4

Yeah.
http://ecomodder.com/forum/showthrea...mer-23893.html

Everything I have read recommends not starting diesel engines below 20'C and 50'C is recommended.

I get that I had 2-3 F-250 diesel's at a time from 02-10. And drove diesel tow trucks in Michigan 22yrs ago.

His idea of warming the trans with water is what i thought was a good idea.

I think his most effective setup would be a block heater in the trans.

Funny story about 'warm up". My partner made a set o billet magnesium transaxle cases for his classic Can Am car. Magnesium expands a lot when hot. So when cold everything is real tight. Even on really hot days the transaxle had to be heated with one of those "turbo" kerosene bullet heaters before the car was started or it would eat itself.

[Daox]

Perhaps you are right about the double acting thermostat. Here is an image of the thermostat in half the housing:

There are a few more images here: Thermostat Replacement

[Daox]

So, moving on a bit past the mechanicals of it all, let me share my current version of the controlling logic.

There are two inputs that will help determine the water pump speed. The first is engine temperature. I'll tap into the coolant temperature sensor to get this reading. The second one is engine load. I'll get this by tapping into the MAP sensor.

The software has a few variables in it to help do exactly what we want. I have no easy way of determining rpm sadly, so that is kind of off the table unless someone has a bright idea that is easy to implement. So, I have a variable that controls the maximum duty cycle of the PWM output, pwm duty cycle that the temperature has effect on, and pwm duty cycle that the engine load has effect on.

Lets start with the first one, max duty cycle. This is pretty easy to figure out. If the temperature signal and the load signal are maxed, your duty cycle will be set to this. For example, lets say its 80%. No matter what, the duty cycle will never exceed this setting.

Now, we have the duty cycle that the temperature effects. For example, lets say this is set to 50%. This means the temperature has 50% of the 80% max that it controls (so its really 0-40% of the total duty cycle). When its cold, it'll spin at only 5% or so and it ramps up linearly with temperature. Once the temperature gets up to operating temperature, the duty cycle will be outputting nearer to the 50% that was set. This variable can be set anywhere from 0-100% depending on what my testing shows works best.

The same goes for the load control, but its slightly more complex. This can be set to contribute 0-100% of the set max duty cycle just like the temperature. However, the load control has a set time delay in it (which is programmable). Say we're driving along and we go up a hill. The engine load hits a peak load of 90% then drops off. Well, the water pump is going to continue to pump as if the engine were 90% loaded for the next X amount of time to remove residual heat from the head and cylinder walls. I have this set to 3 seconds for now. So, after 3 seconds, it'll drop down to its normal routine.

If the two variables add to anything more than 100%, it just maxes out at 100%. So, you can set the temperature to control 0-60% and the load to control 0-70% if you wanted to.

Its not super simple, but its the simplest thing I could come up with. It keeps wiring to a minimum and logic to a minimum yet covers all the bases (I think). If you see any holes or improvements to be made in the logic let me know.

[MetroMPG]

The only thing I'd change off the bat is the time delay after max load. 3 seconds seems short. (But that's based on nothing more than a hunch.)

[nemo]

Why would you limit the ability of the temperature sensor to control pump speed. If the sensor indicated a high temperature that alone should be able to adjust the pump to any speed required.(high temp reading light load)

I find it interesting you are considering load at all. Not saying it's a bad idea. Is this to obtain a more stable temperature? As long at there is sufficient flow to the temperature sensor it should respond indirectly to the load.

One other parameter you may want to add if you use load, load having little or no effect below a specified temperature.

[sqidd]

I think you are making it WAY to complicated.

[Daox]

Originally Posted by nemo

Why would you limit the ability of the temperature sensor to control pump speed. If the sensor indicated a high temperature that alone should be able to adjust the pump to any speed required.(high temp reading light load)

The main reason to limit the pump speed is cavitation. If I spin the pump too fast, it'll cavitate. I don't really know how fast it'll take to cavitate. That is one of the things I asked earlier, and hopefully I'll be able to figure that out in testing. Then, I can set the temperature variable from 0 to that speed. But, I ideally want just enough flow to cool the engine when it is the hottest and under the highest load. Anything more is wasted energy.

This mod will be done after an alternator delete is done, so I do have a limited supply of energy to run the pump. I might as well make the best use of it. If that takes a few lines of code, that is a tiny price to pay.

I find it interesting you are considering load at all. Not saying it's a bad idea. Is this to obtain a more stable temperature? As long at there is sufficient flow to the temperature sensor it should respond indirectly to the load.

One other parameter you may want to add if you use load, load having little or no effect below a specified temperature.

Yes, its mainly for a more stable engine/head temperature, aka elimination of any hot spots. The idea behind the load variable is heat in has to equal heat out. Increased load means increased heat into the coolant. Extra pump speed should assist in that faster than the temp sensor, and reduce the risk of pinging/knock. Perhaps this only means running the pump 10% faster, but that might be enough to reduce hot spots that cause issues. If I had a knock sensor, I'd probably monitor that too.

I'm no water pump expert, perhaps it is way overkill, but those are my thoughts.