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Radiator Mist - beat the overheat

Old 06-16-2008, 01:25 PM
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Radiator Mist - beat the overheat

After swapping engines I’ve had cooling problems pulling my trailer on long grades. The cooling system works fine the rest of the time in stop/go traffic or at highway speeds, I just needed a bit of extra cooling on long steep grades or in the desert. This could also help wash down the radiator if you like playing in mud

Hayden has a product called Rapid Cool Radiator Mist System, but it usually retails for ~$ 80 (Radiator Mist System). I built my system for $10 plus a few spare bits I already had collecting dust. It’s a pretty simple system and only took a few hours for a nice clean install. Now I won’t have to worry about desert temps or cross my fingers that the head gasket will last pulling a grade.

Here's the major components. A junkyard windshield washer motor that I swiped from a Mercedes, a “large” size universal radiator reservoir, 4’ 7/64” rubber tube, 20” 5/16” brake line - you'll also need a momentary switch and some wiring to run run the pump along with an anti-siphon valve to prevent the system from leaking down.

I had to modify the reservoir a bit to mount nicely where I wanted. Using a heat gun I heated the bottle where I wanted it to change until the white plastic turned translucent. Then I pushed in on the corner with a block of wood and held it until the plastic cooled and hardened (cools much quicker if you run water over it).

The spray bar needs to have a directed spray pattern so it doesn’t just shoot one solid stream at one part of the radiator. Using my mighty Dremel and a thin cut off wheel, I made 4 verticle slices in the brake line – 2 offset above centerline and 2 below centerline for more even water distribution across the radiator

Close up shot of the slots in the spray bar - I used a pair of vice-grips to pinch the brake line closed and just for kicks soldered the end on top of that

I mounted the spray bar in the grill behind one of the thicker horizontal sections by cutting 2 half circles and recessing it back in, this will help keep it from shifting around. I decided to use plastic zip ties to hold it in place, although a more permanent solution would be JB Weld

When I run the water without the fan on, you can actually see it coming out the backside of the radiator. The pusher fan whips the water around fairly well and completely saturates the radiator. Although it shouldn't be an issue, I made sure the water didn't spray directly onto the fan motor. I timed about 40 seconds of continuous use with the 2.5qt reservoir, but figure I’ll only need to use this for 1 or 2 seconds at a time, so it should last.

Washer pumps are not self priming, so they must be located slightly below or even with the bottom of the reservoir. Because they’re mounted below the water level, you’ll need an anti-siphon check valve to prevent all the water from just leaking out constantly. These can be found on most rear washer hoses near the actual rear washer spray nozzle. Locate it as close to the spray bar as possible to prevent having to refill the entire water hose every time.
- water flow needs to go in the direction of the arrow -

For wiring I’m running a push button momentary switch that supplies 12V to the pump. The pump ground goes to chassis.

That’s pretty much it. When I see the temps start to climb, I push the button for a couple seconds, wait half a minute and push the button again until the temps start to drop.
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