I was building up speed on the wet and flooded track, but nowhere near the upper ends of the rev range – I was pulling between 5000 and 6000rpm when something metally-sounding happened inches from my head.
The throttle instantly felt light and so I pulled the clutch in and the engine stalled instantly.
It’s kind of hard to know what to listen for when an engine goes bad on you, as you don’t want to be pulling the car up if you’ve just rattled part of your exhaust loose. Keep your foot in when chunks of metal are crashing around the engine will mean a huge bill, however…
I thought that we’d had a main bearing failure, as it reminded me of how it went on my first time ever in the car, and as it turned out the engine had seized solid, so it’s a good job I got the clutch in so fast!
What had happened, however, was the piston had hit an exhaust valve, or the valve had broken.
Either way the valve head had become a part of the piston:
The valve stem had poked out a perfect cylinder of piston, and then everything had mashed up everything else.
The head had also taken a fair beating, although Glenn still thinks this could be repaired with some welding.
Checking the conrods everything seems to be ok, and although there was some light scoring on the main bearings, it’s also an old engine so it was probably just normal wear.
With this much metal spread all around the engine (and it will hide in any place it can), the only option is to totally disassemble everything, clean it in a paraffin bath, blow it out with an air gun, and build it back together.
So what caused it?
We initially thought it was an error with end float settings, but as it’s top end, the more lilkely cause was when I missed 4th gear on the pit straight at Donington. This buzzed it a bit, so we should have probably stripped the engine over Winter – but knowing we’re building a new one to put in mid-season we hoped to nurse it through.
This means we’re butchering a few bits from the new engine, but decided that getting the old one back in for now is our best option.
So it looks like we’ve avoided the big bills, other than time, but it’s still looking very tight for making Brands Hatch this weekend. We’re still hopeful, but we should have our answer within the next 24 hours…