On Alfa number 15
AO Platinum Member
Join Date: Dec 2005
Location: United Kingdom
Re: Loud Tapping Noise
It sounds to me as if the big ends in your engine have gone. It will get worse, and if you keep drivng the car you are likely to end up with a rod through the block, and more damage to the crank.
The loose rattling is usually the bottom of the con rod moving on the crank and the tapping at the top end is the piston hitting the cylinder head due to the extra movement at the bottom
Its a fairly common issue on TS engines, and is ususally caused by running low on oil, not changing or using cheap oil, or from not changing the bottom end shells after a previous cam belt failure.
I have had it happen to me. I bought a tidy 145 cloverleaf, did 100 miles or so ok, changed the oil and after a couple of miles the bottom end sounded like there was loose nuts and bolts in there. The oil pressure light also came on at idle.
You will never be cool driving a Vauxhall.