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With a large oil cooler in front of the radiator, I noticed that the water temperature exceeded 115 °C. At such temperatures, the ECU starts to pull timing to reduce engine power output. I resealed the radiator shroud, cleaned out debris, installed a 160  thermostat (71 °C) and lowered the fan settings with HP tuners, but this was still an issue. The stock radiator had developed a hairline crack in the plastic end tank, which I discovered by luck when running the engine without the radiator and the fan shroud removed. A DeWitts or Ron Davis radiator was my preferred solution, but after adding shipment costs and import taxes the total was above $1000, so I decided to go for the less expensive Engineering Cooling Products (ECP) radiator for the C5. The ECP radiator arrived without any visible damage, which is always a risk when having fragile parts transported long distance. I bought it with a consumable electrode, to replace the flimsy petcock supplied.  The radiator installed nicely an

On the first track day with the Z06, the clutch pedal stuck to the floor as I shifted at high RPM. Imagine my surprise and disappointment. I could pull the clutch pedal up and continue, but it would repeat itself at intervals. I tried the "ranger method" numerous times to bleed the slave cylinder, but it didn't help.  I was about to start pulling down the exhaust etc. to access the bleed screw and purchase a Tick Master Cylinder, but then I found this thread: Clutch bleeding from the mc I figured I should give it a try: I drained and cleaned the reservoir and refilled it with new high temp brake fluid (Castrol React Performance DOT 4). I then applied vacuum to the master cylinder port using a MityVac. As can be seen, a lot of air pockets and old fluid was released. The vacuum makes the slave cylinder collapse, which squeeze out more of the old fluid than when using the ranger method. New fluid is sucked in by the reminding vacuum when the MityVac is removed. I repeated th

The boot lid clicks open with a button, but annoyingly enough it does not raise high enough to slide a in a hand. Eventually, the paint wears away as you grab one of the corners to raise it. I installed a spring from an old welding cable, which helps to push the lid further up when opened. Problem solved! Cost $0.

The GM key fob has no tactile feedback, it reacts slowly and the rubber caps wear out. Fortunately, someone has reprogrammed VW key fobs to work with GM cars - and the Corvette C5. You have to cut the stock key in half. Make sure that you don't cut too far down, otherwise the key will not fully enter the ignition lock - making it impossible to turn the key (BTDT). More information and links to e-bay on the  Corvette Forums

Oily bottom end With an oil pan soaked in oil, it was time for repairs.  I had planned to replace the harmonic balancer with an ATI underdrive unit, but it was simply too expensive after adding shipping costs and 25% VAT. I decided on an OEM PB1117N Dayco balancer. Ouch, what a mess I found non-factory sealant between the front cover edge and the oil pan, so someone has previously serviced the engine. They obviously didn't care about centering the front cover and seal, which resulted in uneven wear of the seal, which again wore down the sealing surfaces of the harmonic balancer. To avoid a revisit later on, I decided to change all other parts that could be causing an oil or water leak in this area. Front cover gasket, water pump gaskets, front end seal. The lower oil pan gasket was changed last year. Removing and reinstalling harmonic balancer The first attempt at removing the balancer failed. I retried with a stronger puller with a sharp end tip, which would secure itself securely

I came across a spreadsheet on corvetteforum.com with reported valve spring failures linked to the car build date. My 2003 with yellow valve springs was right in the sweet spot for a failure, which is not a good mix with track day usage and high RPMs. I decided to use the blue GM Performance valve springs, as I don't have any immediate plans for a cam upgrade. To prevent valves from dropping after removing the retainers, I coil up a rope through the plug hole and then rotate each cylinder towards TDC. When the breaker bar resisted rotation, I know that the rope is pushing on the valves. I then remove the retainers using a magnetic tool and a light tap with a plastic hammer.  While the valve springs are out, it would be dumb not to change the valve stem seals as well. The seals are easily removed using a plier, and I simply push the new seals on using a valve spring. I checked the valve gear for wear. The tappets looked almost like new, and I couldn't find any valve guide wear/p

While disassembling parts of the dash and center console to repair the HVAC display, large pieces of brittle plastic disintegrated. To assemble the parts again, the plastic would need repairs.  Using a soldering iron, a Dremel tool and some leftover ABS plastic and zip ties as additional material, the cracked pieces were rebuilt.  The piece above the thermistor/air temperature sensor was broken off and missing, and was rebuilt by cutting out a similar profile from a piece of plastic. By melting deep into the original plastic piece, the new plastic bonds nicely.  Dremel tool and soldering iron used to repair the broken plastic pieces Repairs finished