bjbeal

I had a similar problem on my '99 Cobra. The timing of the leakage was more random but it would just start spewing from the reservoir cap every so often. I replaced the cap with no improvement. I had also made sure there was no air in the system. I was afraid I had a blown head gasket but test for exhaust gas in coolant was clean. I ended up replacing the reservoir and that fixed it. I have no idea why that worked as the seal on the cap looked fine. You might give that a try.