Note: This event originally occurred on 12 July 2015, I’m a bit behind in my posts.

Following my first full race weekend, which was a mad dash to ready the car, I knew I had a few bugs to work out.  Chief among those issues was a persistently warm running engine.  Of course this was in the heat of the South Carolina summertime, but I wanted to get my temps a little lower.

To that end; I installed a larger CSF all aluminum radiator specifically for the E46 non-M chassis.  Unfortunately the mounting points weren’t ideally designed to interface with the factory plastic mounts.  I did my best to modify the mounts to work, installed it, and off I went to Carolina Motorsports Park for a day of testing.

Spec E46 Testing at CMP

I went out on my first lap and found that the temps were much lower.  Prior to the new radiator I was averaging ~212-215F in the heat of the day.  Now I was sitting at around 202F, much more reasonable.  I pushed on harder for the next couple laps, besting my previous times by more that 2 seconds.  Then on the third or so lap I got a warning light briefly for engine temps.  It went away as I looked down at the dash to decipher what the problem was.  Then a few seconds later it reappeared.  By now I was paying closer attention to the numbers, and I watched as the water temp spiked to over 250F then back down.

I immediately let off the throttle, short shifted, and brought it in to the paddock as quickly as possible using as little engine as possible, coasting the last hundred feet or so with the engine off.  Hopping out I could see steam rising from the engine compartment.  A peek under the car showed hot water dripping to the ground.  This certainly wasn’t any good.  Popping the hood confirmed my concerns about the mounting of the CSF radiator.  It had slipped from its mounts and shifted rearward where the expansion tank made contact with the serpentine belt.   The belt made quick work of the plastic tank, sawing right through it.

My day had come to an early end with a destroyed expansion tank, a radiator that wouldn’t sit securely, and possible engine damage.  Later on, after everything had cooled, I also discovered that high temps had destroyed the expansion tank cap.  The lower portion that retains the sealing o-ring was completely missing.

Damaged Expansion Tank Belt Cutting Expansion Tank

The good news: CSF was quick to help rectify the situation.  They sent me one of their OEM+ radiators, covered the cost of the expansion tank, and promised to redesign their all-aluminum radiator.  Hopefully they get it corrected soon, because other than the mounting problems, it’s a solid piece.

And finally a short video of my one hot lap before the radiator mounting failed:


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