420 sel discovery thread

[larry perkins]

forum i have e new project,why does the 420 have so much trouble with the timing chain?
if you have any theories please post.
i just picked up a 1987 with 217k and the previous owner had been driving making stops at shopping and such, tried to restart the engine and got a loud noise,looked under the hood and the drivers side valve cover now exposed the timing chain.
i have read a lot of the post about the same problem,and will complete a study.
chain tensioner failure would be my first suspect, would anyone know if the tensioner is the ratchet type or does it rely on oil pressure to work?
arry perkins lou ky