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Old 11-01-2015, 10:49 PM   #12 (permalink)
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Originally Posted by oil pan 4 View Post
Those are diesel EGR coolers.
They are made for this and it would not have exhaust flowing through it all the time.
No. These are viscous heaters that tie directly into the coolant system. Nothing to do with EGR.

Quote: "The viscous heater is a pump that churns a silicon gel to generate heat through friction. The heater warms the engine coolant as it passes through the pump's housing en route to the heater core. The pump is driven by the engine's serpentine accessory drive belt and engages via a standard air-conditioning compressor clutch. It turns on when the air temperature is below freezing and the engine is below its operating temperature. Once up to temperature, the pump disengages, letting the engine provide heat. But even a running diesel can cool off too much, such as when idling at a traffic light, so the heater will reengage if the coolant temperature drops."
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