It's morning in July, promising to be a hot day. Big XJ12 and I'm hooking up an even bigger 6mtr caravan. I bungle the job and drop the caravan hook. I recover and connect. I load the family and we set off for the Peak District some 150 miles away. The kids are noisy but we proceed quite quickly. Sun well up and we are near Huddersfield when I notice the brake pedal going soft - worries all round.
Not much of a handbrake on an XJ12 and now the pedal's hitting the floor. I stop at the crest of yet another big hill refusing to risk anymore descents. I switch off and I can hear what sounds like a kettle boiling under the bonnet. I open the top and detect the boiling noise is coming from the brake reservoir. I'm running on DOT5 Silicone Brake Fluid which I know boils at 260deg so it's very hot - the boiling point of water is 100deg at sea level - then I do a really stupid thing. I unscrew the reservoir cap and what happens next could have been catastrophic.
The hot fluid erupted like an oil well, spraying scalding brake fluid over all the front of the car - and me!
Fortunately it was Silicone so no damage was done. Had the fluid been DOT3/4 'glycol it would have failed sooner with far less warning and would have meant a complete respray - Ouch! It could have been much worse - The fluid could have burst into flames when it hit the hot manifold and that would have been that.
The AA took the car to the local Jag dealer and the caravan to a caravan place. It was subsequently discovered that the caravan brakes had not been working, obviously because when I dropped it, the overrun mechanism was damaged and the car brakes were doing all the work. Even worse I clearly failed to test that the over-run brakes were working. There is an important lesson there for all you caravaners
Carrying no spare Silicone I had to quietly let the Jag dealer refill and bleed the system with 'glycol fluid so that we could carry on with our journey. Suffice it to say the very first job I did when we got back was to replenish the whole system again with Silicone and no doubt it's still in use today some 20 years later.
Perhaps the moral of the story is... "You get what you inspect - Not what you expect"