Why Do I Need A Super Duty Cooling Kit?
The factory cooling systems on e39 and e38 Bimmers have a number of weak points. The plastic radiator tanks and
expansion tanks are well known for failing. Glass reinforced nylon just doesn't hold up under such high operating temperatures.
However, these cooling systems have another short coming that has the potential to be even more devastating. What is it?
The plastic engine driven fan. How? The only adequate description is explosion. Over time, the fan deteriorates and can no
longer withstand the centrifugal force at which point plastic shrapnel is sent in every direction. Hopefully, the hood is closed
when this happens. Otherwise, serious injury or death could result. (Check out the picture of the damaged hood below.)
These pictures are of a 1999 540i with approximately 89,000 miles of use. Unfortunately,
the fan exploded and took out the majority of the factory cooling system, including a replacement radiator. A list of the
major items destroyed and their replacement costs follows.
Replacement Cost of Items Destroyed by the Exploding Fan
|1) 11 52 1 712 110
|2) 17 11 1 436 063
|3) 17 10 1 440 252
|4) 51 71 8 159 98
|5) 17 11 1 741 167
|6) 51 48 8 159 483
|7) 41 61 8 238 592
|* excludes labor and paint|
The destruction of plastic items is disturbing enough. However, if one examines the picture of the hood to the left, it will be observed
that the fan was moving at such a velocity that it not only destroyed the hood pad,
but split the sheetmetal. A search of popular BMW forums will also reveal that this is not an isolated incident.
We believe BMW owners deserve a safer and more reliable cooling system... and that's just what we've produced. Our
Super Duty Cooling Kits eliminates the 3 major weaknesses of e38 and e39 cooling systems for about the same cost as
factory replacement parts. Read the details below.
E39-E38 Super Duty Cooling Kit
('95-98, Type 10; '99-03, Type 9)
A number of things contribute to cooling efficiency, e.g.; fluid capacity, fin design, material, etc. Zionsville Autosport's Alloy Radiator has a core thickness of 43 mm. The surface area of ZA's e38 - e39 alloy raditaor is 376 square inches - the same as a stock radiator.
Additionally, we use a high efficiency core similar to a stock radiator. High efficiency cores have more fins per inch, more tubes per core and more cooling capacity. Each row has a single, large tube. The flat side of the tube is in direct contact with the fins which transfers heat from the tube walls to the fins. Since the rounded ends of the tube are not in direct contact with the fin, this portion of the tube does not aid in secondary cooling. The more tubes per row, the more rounded ends, and the less direct contact there is between the tubes and the fins. ZA uses a single tube for better heat dissipation.
The E38-E39 Super Duty Cooling Kit... The alloy fan shroud and electric fan work in concert to provide maximum cooling efficiency by pulling 2070 cfm through the radiator core - even while sitting still if required by engine temperature. Simply hanging a fan on a core is inefficient as airflow must be directed through the entire core area, not just directly in front of the fan. The latter approach limits the effectiveness of the core. Essentially, it reduces the core size to the diameter of the fan. Not to mention the fact that hanging a fan through the core will eventually fatigue the cooling tubes and lead to failure.
The alloy shroud in combination with the electric fan creates a low pressure area behind the radiator in order to pull air through the entire core surface. (The front of the core is exposed.) The concept is a refinement of the BMW design. Our kit features improved sealing of the shroud and increased air flow without the parasitic drag of an engine-driven fan. We have also been advised by both customers and technicians that the engine fans are disintegrating at around 100k miles, taking out the cooling system and damaging the hood of the car. Our design incorporates a caged electric fan with a safety shroud and lighter weight individual fan blades. The result is improved safety and efficiency.
With regard to the expansion tank, we have been advised and personally experienced tank failure through rupture of the main expansion tank. Our thinking is that due to higher heat soak temperatures on V8 and V12 cars, the tanks are heated/ pressurized beyond their limits. As a result, we designed an alloy expansion tank with greater resistance to degradation caused by the more extreme temperature limits in V8 and V12 cooling systems. Our tank does incorporate some of BMWs features; e.g., we retain the original cap and the internal plumbing.
The cap design is very clever: it facilitates the expansion and contraction of coolant, while at the same time offering an escape route for atmosphere and coolant when pressure in the system threatens passenger well being *** and cooling system integrity. The topping off process requires filling the tank until one half the level is maintained during the initial fill, then topping off after a driving cycle, once the cooling system is cold. As in all our radiators, the alloy construction of the radiator also improves efficiency through an increase of radiant surfaces and enlarged storage capacity.
With the 2 speed fan kit, the fan operates on low speed or high speed based on engine temperature. High speed comes on only when necessary. Running the fan through a resistor allows us to back the speed down when the extra volume is unnecessary, creating less wind noise.
* The 1999-03 V8/12 automatic cars require an additional hose.
*** Otherwise, the heater core could rupture and spray coolant inside the passenger compartment.
1997-98 528i, 1997-03 540i, 1999-03 540it
1995-01 740i, 1995-01 740il, 1995-01 750il
Additional Images (Click to Enlarge)