I wondered how the secondary tensioners behave, and what exactly happens when they fail, since they seem to be spring loaded?

Do the secondary tensioners pop up and down as the camshaft rotates when starting, or do they go up and stay up until oil pressure retracts them?

If they pop up and down, wouldn't this cause the secondary chains to alternate between a slack and tensioned state, with a risk of jumping off the tensioner guides?

And when the tensioners fail, do they stop in a retracted state, causing the chains to stay in a slack state, and jump off the sprockets at some point almost immediately after tensioner failure?

These might seem like silly questions ( i'm good at those), but i just wondered exactly how they behave when working properly, and when not (working properly).

 

The springs only are needed at start up. When running, oil pressure holds the tensioners extended.

The tensioners fail when the Plastic Body or the Plastic Wear Shoe shrinks and cracks with heat and age. The entire body can come apart from the metal inner cylinder, or the wear shoe can detach from the end of the ram.

Either fault can cause plastic parts to get caught in the chain or fall into the crankcase. And, of course the chain can be damaged by riding on the Metal end of the ram.

 

Sorry for not replying earlier Paul, RL has got in the way of things Jaguar lately.