When you overheat in the Badlands of South Dakota, it's an inconvenience. When you overheat in the Badlands of Iraq, it can quickly become a life-or-death problem.
That's exactly the scenario Army Chief Warrant Officer Pat Milton was experiencing during a deployment in Mosul last year. His company's M1114 Humvees--nicknamed "Turtlebacks" for their slanted rear roofs--were seeing operating temps of 250 degrees or more due to the stress of carrying soldiers, weapons, and ammo in 130-degree temperatures with the A/C at full blast. "I cooked three engines in the first month and a half I was there," he said. "Everything else checked out, but I was cooking the engines in three- and four-month-old vehicles." Catastrophic engine failure was the biggest problem, resulting in very expensive--and time-consuming--repairs and engine swaps. But the overheated motors also triggered the limp-home mode in the transmissions, so that they wouldn't upshift beyond Second gear. Try running away from pissed-off Iraqi insurgents in a 14,000-pound Humvee with only Second gear.
The M1114's radiator design doesn't do it any favors in the Middle Eastern heat. The radiator sits under the hood almost parallel to the road--not straight up in the air stream--and there's a massive oil cooler mounted on top of it, which further blocks fresh air from reaching it.
Soldiers tried all sorts of remedies, from disconnecting the engine-fan control module so the fan ran constantly (which sapped the engine of much-needed horsepower) to rigging hood scoops that worked when the vehicle was moving, but were ineffective in traffic or when idling.
Milton, a Jeep owner stateside, figured there had to be a better way. "So I broke out my Summit catalog and started looking at electric fans." Due to the Humvee's underhood design, he knew he needed a pusher, and it had to be thin enough to allow the hood to close.
He found a good candidate in Flex-a-lite's Low-Profile 230 pusher fan. It moves 2,500 cfm of air, draws just 19.5 amps, is easily connected to a 12-volt system, and, with a width of just 2 5/8 inches, is compact enough to fit under the Humvee's hood.
"In the Army we have a credit card with a $2,500 spending limit," Milton said. "I contacted Summit to see if I could order 10 and have them sent to an APO in Iraq." He did, they were, and those fans immediately went into service.
Installation was a snap, he said. "The fans bolt to existing holes in the oil cooler [which sits on top of the radiator] like they were made for it. The thermostatic fan relay switch mounts to the front of the fan shroud, and the sensor plugs into the radiator hose prior to the thermostat, giving us an accurate reading from the engine." Though the Flex-a-lite fan is designed for a 12-volt system, the Humvee works off 24 volts. "So you hook it to one battery, then wire it to the transmission control light, giving you the 12-volt ignition source you need."
Right away the fan-equipped Humvees showed lower engine temps compared to those pulling the same duty without fans. "Since installing these auxiliary fans we have not had an engine exceed 230 degrees on the road or 220 degrees at a prolonged idle, even with the ambient temperatures exceeding 125 degrees," Milton wrote in a report to his superior officers. "Crews have reported cooler crew compartment temperatures, more horsepower, and better fuel economy."
Milton had found a way to spend about $200 and two hours installing a fan to prevent the days-long job of replacing an $11,000, 6.5L turbodiesel. He immediately put in an order for 80 more, to equip the rest of his pool. We've all heard horror stories of the red tape you have to wade through to get anything done in the military, and we asked Milton if he had any trouble getting the fans.
"Well, I'm in a Special Forces unit, and we have our own, um, avenues of getting money. That's the only red tape I encountered, getting the money. It didn't happen as fast as I wanted, but command thoroughly dug it, so there was no problem getting it done. But when you send a $16,000 request to the bean counters, it gets slowed down. They don't have the same sense of urgency as you do."
When the funding was secured, Milton contacted Bruce Erickson at Flex-a-lite and ordered his fans factory-direct. "Then I did what every good paratrooper would do: I put it on the street for everyone. I wanted to get the word out to these guys, to get their units to buy these things. I wanted them to get their butts out of harm's way on these roads." Milton produced a PowerPoint presentation about the aftermarket fix, a presentation that got passed around to a lot of other units. Another Chief Warrant Officer overseeing vehicle maintenance, Jerry Bechtol, was so impressed that he ordered 400 of the Flex-a-lite fans for his Humvees.
Milton also sent his low-buck fix up the chain of command, thinking it could become either a permanent Army fix or even an upgrade at AM General. So far the change hasn't been adopted at that high level, "but our guys are doing it on their own,"he told us. "We have to take care of ourselves."
Flex-a-lite's Low-Profile...
Flex-a-lite's Low-Profile 230 pusher fan was a perfect fit for the tight confines of the Humvee's engine bay. Plus, it bolted to existing holes in the oil cooler.
Wiring the fans was simple...
Wiring the fans was simple too; no splicing was needed. They were driven by one of the Humvee's two batteries.
Pat Milton tested his overheating...
Pat Milton tested his overheating fix during convoy duty out of Mosul, Iraq. "This is refit day before we hit the road back to base after the long convoy through Tal Afar and to northwestern Iraq," he writes. The fans dropped engine temps by a full 20 degrees, both on the road and at idle.