Help me diagnose this engine problem-please
Hi all, I'll cut streight to the chase.
My 2001 156 selespeed lost all its coolant whilst doing 70ish and I didn't notice for another 7 miles (about 5 minutes) until I saw the temperature and she stated making pinging/tapping noises. I've now fixed the cooling system and it stays at the correct temperature and the oil level was at the max before and somewhat about the max after so no oil starvation has occurred.
The problem is I've got a definate tapping/knocking from the top end, it's not so noticeable at tick over but at all other revs you can hear it. It's there under load and coasting/engine breaking and when hot and cold. I've changed the oil and filter and all spark plugs because the plugs of no. 1 cylinder were black/sooty/wet but the others were fine. The new plugs have been in for les than 10 miles but the plugs of no. 1 cylinder are already darker than the rest, I can also see that the crown of no. 1 piston is wet through the plug holes. I've also got a vibration at tick over that you can feel in the cabin but I know that all cylinders are firing because I've disconnected each coil pack one at a time and you can tell the difference.
Can anyone please offer any advise what could be the problem.
Oh, the engine only has 58000 genuie miles on it cause I've had it from new.