We are frequently asked why we only offer a 30 day warranty on individually sold cores instead of a similar warranty like fully assembled units. Each core is tested prior to shipping to ensure they were properly brazed, but the unit still has to be assembled with its tanks. Unfortunately, this is where a lot can go wrong.
Before we talk about why the final assembly procedure is so important, let’s look at how the core is built and tested. The build process for cores is similar regardless of whether it is a charge air cooler, oil cooler, or radiator. All that changes is the types of materials used (stuffed tubes, radiator tubes, extruded tubes, etc.). Alternating rows of tubes and fins are sandwiched together and held in place with header plates (the tube ends are fitted into the header plates). The headers become the mounting point for the tanks after the core is brazed. During the brazing process, the tubes are joined to the header with a brazing material that locks everything into place. At this point the primary failure points are the brazing joints where the tubes and headers meet.
To make sure the brazing completed properly, we air test each core and look for leaks. Any leaks found means the unit did not braze correctly and cannot be used. These tests cover the majority of our cores, but there is also our Ultimate Duty C-Bar Design that doesn’t use header plates. For C-Bar units, the tubes are brazed to each other since there is no header. This allows the tanks to be welded directly to the core and eliminates the header and all header joints as possible failure points. Since these cores are used in applications that require a tolerance to extreme heat and pressure, they are pressure tested in a special machine to ensure they have brazed properly before shipping.
Having a core that is in good shape is one thing. Having a fully assembled unit with good tanks and good welds is another. There are two reasons we only offer a 30 day warranty on our cores. The first is because we cannot control the type of product the core is put in. We have seen where a standard charge air cooler core has been used to replace a core that should have been made using our C-Bar design. Similarly, we’ve seen radiator cores put in oil coolers. Since we do not know how the core is going to be used, we cannot guarantee that it is suitable for the intended application. A unit that used the bar and plate design would have to have a core from us that uses our C-Bar design. Anything less will not hold up to the heat and pressure the original unit experienced. Similarly, we only provide C-Bar designed cores for oil coolers because of the amount of heat and pressure they have to hold up to. Using the wrong core for a unit will lead to premature failure.
The second reason is because of the damage we have seen that occurs during assembly and that. When we re-core existing units, we thoroughly inspect the tanks to ensure that they are still in good shape. Significant deterioration, cracks, and other issues can cause the assembled unit to prematurely fail and even damage the core. Additionally, we’ve seen people use various grips and stands to try to the hold the core in position while welding the tanks. Overly tight grips can damage tubes and headers, and may not be noticed until the unit is put into use. The biggest problem though usually comes from the welds.
A good weld not only looks good but also fully joins the two pieces of metal together. A poor weld will look horrible and can create numerous problems from blocked tubes, tanks separating from the core, and numerous other issues. Many of these issues may not be noticed until the unit is put into service. Take a look at these two pictures:
Pictured above is a clean weld made by us (left) and a not so clean weld on a unit sent in for repair (right).
On the left is our weld from a completed unit. The right is one that was sent in for repair. The quality difference is fairly obvious. At the end of the day, the reason we cannot warranty cores for more than 30 days is because we are not in control of the final stages of assembly, and there are too many things that can go wrong during that process. Ordering a core by itself is a great way to save some money, and the build process can be enjoyable if you like welding and working with metal, but you need to make sure that you are using the correct style core for the intended application and that the tanks are in good condition. If you need to make sure your unit is fully functional the moment you put it in use, then we can re-core your existing unit for you and give it the full test all of our other fully assembled units get. At the end of the day, it’s simply a matter of what you prefer and how you want to spend your time.