So, on the very first drive after the engine rebuild I was gradually increasing the boost when I suddenly felt the power drop. A glance in the mirror and I couldn’t see anything behind at all but steam – the head gasket had failed in a big way. Cut the engine straight away, coasted into a lay-by and called the breakdown company.
Pulled the head, replaced the head gasket which had blown on cylinder 1 and she was running again, but making huge smoke once she started warming up. The compression was about 30% lower on cylinder 3, so I thought perhaps I’d cracked the head. Embarrassingly it was weeks before I realised that the smoke was because the rear silencer was saturated in coolant. Flushing it with a hosepipe solved it, but she still wasn’t running right – running lumpy at anything above idle.
I decided to instead concentrate on fixing a little hole by the right front side jacking point:
Eventually I decided I was going to have to pull the engine back out and tear it down.
The first ring had broken on piston 3, chewing up the piston and the bore and somehow also cracking the lower ringland?! To boot, even the bearings and crank are scored, presumably either from bits of ring, or perhaps I didn’t get every bit of crank sprocket.
The cause of all this? Turned out in my rush to get the car back together, I’d refitted the crank position sensor in the original position, not the one I worked out it should be in when I did the T5 conversion. So, the ignition timing had been 18 degrees too far advanced.
Currently I’m just waiting for the engine shop to reopen so I can find out what can be salvaged.