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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.
jamie
2025-09-02 16:21:11
It was a very good kit and installed great. Truck runs much cooler now
Customer
2025-08-19 10:38:15
I bought this kit and the pipe that is shown in the kit is not the pipe that you will receive and the seller insists that it is correct. It does not work as the only way to fit this on your truck is to the original pipe which has 2 outlets and you have to run the risk of completely damaging your engine if the blocked outlet gives way. You will receive a straight pipe that does not fit. The seller will refuse to make this correct and you will lose your money,. Buy from someone else or look somewhere else....
Ethan K
2025-07-22 12:59:14
Great
todd s.
2025-06-22 16:36:36
easy to install with engine out
Eric Forbes
2025-06-10 15:44:59
The quality of this product is top notch, but the suggested install time of 1.5-2hrs is far from accurate for vehicles with an automatic transmission. I had the entire front end of my truck disassembled to replace the inner timing case gasket and figured it would be a good opportunity to install this kit. Even with the radiator, Air charge cooler, front bumber, etc removed this install still took me around 2.5hrs and I'm a certified diesel mechanic. Plan for an additional 1-2 hrs if you plan on removing the heat exchanger which I highly recommend.
Cory
2025-01-14 17:04:45
The photo is "generic and cant be changed." Is what i was told when i didmt get the new coolant line that heads toward the heater core. The 1 in the picture is not what comes in the kit. Keep all of your old connections,tubes,clamps,and rubber connectors because u will need them. This kit allows you to eliminate the heater grid for tranny fluid ONLY. You can not retain it with the parts included. You can still use it,but u need a new connection x over pipe that will fit around the Fleece coolant block that mounts behind the block im place of the rear freeze plug. They only supply a long straight pipe that goes toward the heater core,and a new "S" style hose for the connection on the fire wall.Pain in the ass with engin,trans,and head in but can be done. I did it with basic tools in my driveway.Make sure to really clean the mating surface of the block off plate before mounting. I used a very light skim coat of hi flex oil resistant high heat PermaTex around the surface to keep corrosion from forcing its way in between the aluminum plate n iron block. (IT HAPPENED ALREADY!!)
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