Joe,
Ill try and explain what happened. I was on the motorway coming back from Sheffield and was nearly home after about 100ish miles of doing between 70 and 90 mph. I was doing about 80 mph in the middle lane coming up to a car going slower than me so I pulled into the top lane I applied a little more gas to over take the car and it felt as if the breaks were being applied slightly, the induction note was getting louder but there was no power there the engine was struggling to accelerate, there was a loud knocking noise coming from the engine when I tried to accelerate. I pulled back in and started decelerating when the engine started making a humming noise. Ten seconds later as you said the car tried to stop its self felt like someone had slammed the breaks on, obviously because of the speed I was doing the car was not going to stop instantly. This is when there was a big bang and clatter from the engine, there was a plume of white smoke from the exhaust and loads of steam from under the bonnet, there was a clatter of what sounded like metal parts hitting the floor of the car and I saw some parts bouncing down the motorway (didn’t go back for them, forgot in the heat of the moment). I have tried to turn it over with the starter motor but the engine made a very nasty knocking noise the It jammed the starter and a load of oil came pissing from the bottom of the car. I then looked under the car and found a big hole punched in the plastic sump cover. All together not a very nice experience.
Tim.