Fix It Up Right
An EGR cooler is essentially a bundle of small tubes grouped together with a heat exchanger going around them inside a larger tube that’s all welded together. When things heat up, they expand. The way the stock EGR cooler is built, the tubes are straight and they really only have one direction they can expand: laterally into the bulkheads. The amount of force that is now applied to the ends of the tube is through the roof, and with nowhere to go, they simply fail. Ken explains, “If you’ve got a spring, you can bend it so far and it’ll snap back, but once you take it past its yield point, it never is the same again. It’s never really a spring anymore. Once that exceeds the yield on these ends of the material it starts to fail. If you don’t have enough coolant cooling that down, moving around it fast enough, it’ll allow it to overheat. It will then kill itself.”
For a while the only way to “fix” the problem was to delete the EGR cooler altogether, but Ken knew that besides that being a violation of EPA law, that wasn’t really a solution. “I was taking a shower one day, daydreaming about how I could fix this problem, and I came up with this: we could actually turn the tubes instead of a structural member of a column, basically, into a spring, so that as it goes, it can grow out and away and won’t put very much pressure on the ends. You have to understand the method of failure before you can understand how to fix it.”
The way Bullet Proof’s EGR cooler works is ingeniously simple. Simply twisting those tubes into a spiral or spring shape allows them more room to expand in other directions before that expansion puts pressure on the ends of the tube and breaks the weld, causing the cooler to fail.
Who knew that it could be such a simple fix? Ken says that ever since they’ve introduced their coolers to the market, they’ve never had a single one fail. I guess there’s a reason they call the company Bullet Proof.