What makes an engine go Bang?

[lakelandterrier]

Excitement at Dittisham on Saturday. I was enjoying a pint of Broadside on the pontoon whilst Lakeland pup 2 was crabbing when I heard a huge bang and glimpsed something shooting oveer the water a la bouncing bomb. This was followed a few seconds later by a cloud of smoke & a shout to the equivalent of "oh dear we've got a fire". I grabbed the extinguisher & raced to the other side of the pontoon where there was a large dory with its OB well aflame. 2 extinguishers put out the fire & fortunately no-one was hurt. The engine - a 115Hp Evinrude was a right mess though. What I had seen was the cover flying over the water as it blew off.

The owner reckoned he had just turned to key as normal to start when it went bang. What could have caused this?? It was very impressive, but musty have been rather scary for those on board. Lucky they were still tied to the pontoon.

[codprawn]

Must have been a build up of petrol vapour under the cowling. or maybe he had just sprayed something like WD40 or Easystart into the housing. Most aerosols these days use butane gas as the propellant since inert CFCs were banned.....

I had an interesting experience once. I started my V8 landrover and there was a loud bang and a pop. The engine stopped dead and I thought the alternator had gone opo - sounded like diodes blowing after the bang. When I looked the dizzy cap was off completely. I had use electrical cleaning spray on the dizzy cap and the alternator. Because the weather was so cold it hadn't evaporated. Reffited the cap and it was fine. The forces must have been incredible to blow the cap off even though the clips were in place!!!

As the fire kept going I would suspect a fractured fuel pipe or similar.

[bedajim]

Originally Posted by codprawn

As the fire kept going I would suspect a fractured fuel pipe or similar.

So could that not have been the problem from the start

[codprawn]

Originally Posted by bedajim

So could that not have been the problem from the start

Yes - I did mention petrol vapour but it can come from sources other than a broken pipe!!!

[ribraff]

Wow... i heard a big bang on saturday too and we're down at Noss marina.... could it have been one and the same???!!!

[doggypaddle]

I experienced the flying off dizzy cap too, and it was.........V8 landrover!
same fuel too! it must be quite common, after all everyone with a V* landrover must of at least once had to dry the cap out to get it going, after all a V8 only has to smell water to stop!
Backto the original topic i had a johnson overheat that went bang, it was a core plug that blew out, it was on the block and had oil behind it, it was a blind hole too, i did vaguely wonder if it used the vaporising oil during an overheat to blow the plug out as an audible warning or warranty indicator to show if over heating had occured?

[lakelandterrier]

Originally Posted by ribraff

Wow... i heard a big bang on saturday too and we're down at Noss marina.... could it have been one and the same???!!!

If it was about 5.00pm yes. It was one hell of a bang! I nearly split my beer!
Lakey T

[codprawn]

Originally Posted by doggypaddle

I experienced the flying off dizzy cap too, and it was.........V8 landrover!
same fuel too! it must be quite common, after all everyone with a V* landrover must of at least once had to dry the cap out to get it going, after all a V8 only has to smell water to stop!
Backto the original topic i had a johnson overheat that went bang, it was a core plug that blew out, it was on the block and had oil behind it, it was a blind hole too, i did vaguely wonder if it used the vaporising oil during an overheat to blow the plug out as an audible warning or warranty indicator to show if over heating had occured?

I learnt my lesson and in cold weather I use a hairdryer to force the stuff to evaporate!!!

[doggypaddle]

"I learnt my lesson and in cold weather I use a hairdryer to force the stuff to evaporate!!!"


"Thats a good idea, but i never had much luck finding a hairdryer in the middle of the brecon beacons when i needed one!:-)

[Hightower]

Was it an Etec or the older DI Ficht engine?