Electric water pump

[s'ko]

Anyone tried the idea of making an electric water pump for their Soobies?

Here is what I have so far. Get a 180F fan switch to turn on at the same time the thermostat opens at 180F. I was thinking of putting the water pump at the bottom of the radiator to let gravity prime the pump.

Here’s where it get’s interesting. I was thinking about using a 12v marine bilge pump, maybe the one from harbor freight. The inlet is 3/8 inch and the outlet is ¾ inch. It flows at 120 GPH at 5 psi. The stock water pump flow rate is 20 GPH.

So I will have a system that will narrow to less than an inch at the pump and then widen to 2 ½ inches or so at the radiator and engine. Is that going to be a problem?

I am hoping that the larger hoses will keep the flow rate down. I realize that if the flow rate is too high, then the water will not have proper time to cool.

So what do you think? Possible? To expensive? To complicated?

[keltik]

Ok im curious....

 

Why would you?

[idosubaru]

sounds like a cool idea, but i wouldn't use a harbor freight pump. i love the place but you definitely have to keep in mind the quality of many of the items they sell.

 

how do you deal with the old water pump - gut one and leave the housing so you can retain the flow paths?

 

is there a problem with the stock pumps? doesn't seem like there's anything to gain here.

[[HTi]Johnson]

I'd guess the outlet of the stock system to be 1" to 1.25". I wouldn't put anything that would restrict the flow.

 

What you'll have is the water pump trying to push 20gph through a 5gph pump if the system is setup like that and if it's the other way, the 5gph pump would starve the 20gph pump of water and cause cavitation and probably over heat.

 

Find a pump with a bigger outlet/inlet and maybe higher gph, you'll be onto something.

 

I thought about doing something like this on my Turbo'd GL-10. I know some VWs have electric water pumps that will run after the ignition is turned off to cool the car faster.

[DaveT]

1985 Mercedes Bens have an electric water pump in the cooling system to move water through the heater core when the engine is at idle. Something like 5/8 or 3/4" inlet & outlet. I have no idea on the flow rate. BUT the pump is designed to operate at 15 PSI and high temperature (at least 200 degrees), unlike a bilge pump. Maybe you need 2 or 3 parallel to get the flow?

[ScottG]

I remember reading an article back in the early '80s, when VW introduced the water-cooled flat 4 wasserboxer in their vans. The article revealed that one of the reasons VW was making this change was that the squirrel-cage fan on the air cooled model used up some 4 or 5 HP, while the water pump used something like only .3 or .4 HP.

 

Using this as a basis for argument, you won't gain any usable HP from the change. Electric pumps, as has been pointed out, can be unreliable & they will use more power than you'd save.

 

And my last argument: you won't be able to have the pump cycle off & on with a temp switch. Coolant circulation is needed as soon as the engine starts to warm up (within a minute or 2). Waiting until the thermostat opens will ruin the engine from the hot spots created due to lack of circulation.

 

Sooby engineers created a great piece of machinery to move their cars. It can be improved upon.....but I'm fairly certain that an electric water pump would not be one of them.

 

If you insist upon an electric pump, check the racing & hot rod magazines. I've seen ads for them there.

 

Sorry for throwing cold water on your idea - I just don't see it as practical.

Sooby water pumps are probably one of the more reliable parts of the engine.

[keltik]

Our 2002 Merc Sprinter has a small pump to circulate coolant from the engine through the heater core once the motor has been shut down. It bypasses the radiator so you can get good heat for 10-20 mins and as it doesnt need to cool the motor - doesnt need a high flow rate and therefore doesnt have an issue with the engines pump not spinning.

 

Very usefull if your getting gas or just making a short stop. It keeps the cab toasty warm. :-p

 

Are you looking for this kinda feature with your pump or trying to replace the engines mechanical pump altogether?

 

Edit: Now that i think about it, my dads old volvo had a similar feature to cool the turbo after shutdown (and the rad fans would cycle on for 5 mins after you remove the key).

[porcupine73]

Hm..interesting idea! The Subaru water pump is probably more like 20-40 GPM (gallons per minute) (depending on rpm, etc), equivalent to 1200 to 2400 gallons per hour (GPH).

 

SummitRacing.com sells many electric water pumps in the 20-40gpm range, those might work. Some are just electric motors intended to drive the existing water pump; some are pump and motor in one unit. These appear to commonly used for drag cars.

 

I think you would need to run the water pump all the time though, even during warm up. The coolant still circulates through the heater core and throttle body when the thermostat is closed. The thermostat needs this flow so that it can tell when the coolant has reached sufficent temperature to open. Plus the localized overheating potential without the pump running.