I have a few, but I'll only list the ones that have cost me money to rectify..
When I had my XD 302c I decided it would be a good idea to fit a bigger cam to get some more grunt, didn't matter that the motor was bone stock. So I went out and bought a TQ30 cam, which from memory has about .520 thou lift. The next day I headed off for Monkey Mia, in northern W.A, only to break a valve spring 400k's up the road and drop a valve and destroy the motor. ended up costing me about $2200 for a new motor and to get the car home.
Destroying the C4 Auto in the same car with the recently fitted motor, running late for work and living in Somers at the time, there is a long straight road leading out of Somers that I thought would be a good place to make up some time, and being early in the morning decided to give it a bit. So I'm doing 196k/ph (thats what the speed said anyway) and when I lift off to slow down there is a horrible vibration then an almighty bang. I looked in the rearview mirror to see if anything had fallen off only to see a cloud of white smoke and a largish peice of metal flying through the air about 30ft off the ground.....shit I think.....stand on the brakes and pull it to a stop, get out and have a look around, can't see anything obviously wrong, apart from the car idling very rough, have alook under the car, and see what the problem is.....The C4 has lunched itself. The bellhousing had broken into 4 peices, it snapped the starter motor off, broke the input shaft, bent the output shaft, broke the extension housing clean off, and the peice of metal exiting out the rear of the car, was half of the driveshaft, I never found the other half. that episode only cost me $500 or so, and 2 taillights, coz I kicked them in out of frustration.
Changing a cam again.....
Took a week off work so I could muck around with the car and do a cam change.
All went smoothly until it came time to fire up the car with the new cam in it.
My Dad and myself tried for 3-4 days to get it going, adjusting the dizzy recharging batteries overnight coz they had been flattened trying to get it going, pulling it apart TWICE because the oil pump drive fell into the sump, we finally gave up and organised to have a friend of my dad's who has his own workshop to look at it, thing was he was in Clayton, and I was in Glen Forbes, about 100k's away, so I Borrow a car, Hire a trailer and get the car up to him, he looks at it for 2 minutes and says the
distributor is buggered......It seems when I was puttign it back together I broke the hall sensor.
So that one cost me about $300. Second hand dissy, trailer hire andd fuel.