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Your cart is empty.Another product from Fleece Performance built out of necessity is the 2003-2013 Cummins Coolant Bypass kit. The Cummins engine cooling system was designed to adequately cool a 300-350hp engine. When the horsepower is increased there is an increased demand on the cooling system. The rear cylinders suffer from a lack of coolant flow, and therefore, experience the highest coolant temperatures. This can cause excessive pressure to build in the system, especially the rear of the block and possibly blow out freeze plugs externally, or the smaller diameter plugs under the valve cover, leading to a failure. Weve designed our coolant bypass kit with a secondary thermostat, that unlike other brands, works based on temperature instead of excessive pressure. This solves the problem before pressure becomes an issue by ensuring consistent temperatures across all six cylinders.
Jacob Wilson
Reviewed in the United States on January 2, 2023
I installed this on my 12-valve Cummins after the engine overheated due to a failed-shut thermostat. Prior to installing the kit, I replaced the thermostat in the engine. This was more of a peace of mind addition after the fact.In theory, this is a great kit. In reality, it's less than ideal in the quality department considering how much it costs.Upon installation, my engine now struggles to get up past 145F in colder weather (around 35F outside). Driving around town at low speed will get it there, but cruising at 55mph takes it right back down. This only started after the kit was installed. The new thermostat that I put in the engine after the initial overheating operated normally before this kit was installed, and in the same outside conditions. Clearly, this indicates a faulty thermostat. I am not looking forward to replacing it but will have to do so as running the engine that cool is horrible on fuel economy and not great for the engine either.Second, I had to temporarily disconnect the bypass hose at the front AN fitting to do some work in the area. When I went to hook it back up at the end of the job, I had to REALLY crank down on the aluminum fitting to finally get it to stop leaking. I was worried the AN elbow that goes into the thermostat housing was going to snap off, as it is also made from aluminum. Both fittings feel quite soft (low-quality aluminum) and are significantly chewed up from the tools/force required to get it tight enough for the leak to stop. I won't dare remove it a second time.I expected much more for my money. If you can get another similar kit for less money, you'll probably get the same quality for less $$.
Laura R
Reviewed in the United States on December 2, 2019
Great product and a must have for any Cummins engine
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