Rover 25 - Mark (RLBS)
3.5 years old. 30,000 miles.

Three times in the last 9 months it has burned out the plug and valves on No. 4 cylinder. Each time the plug and valves have been replaced and been ground back in, or whatever they do.

When its not just on its way out, it runs fine.

It looks like its about to happen again. The dealer has been in touch with Rover but as far as anyone can work out this is not a well known fault. The dealer is at a loss. It has had at least one new cylinder head in this time.

This is a colleague's car, so I'll need to check with her if any further details are required.

Any ideas ? The garage is at a loss.
Rover 25 - T Lucas
Sounds like it could be a fuel mixture prob so could be No4 injector,change completly or swop with another,and then check the plug after a few hundred miles to see if it is different to the others.
Rover 25 - DL
Is there ever any sign of misfiring? HT and Coil/spark plug faults are known on these engines, giving a misfire.

The injector theory above is a credible one and certainly one to try I think.

Perhaps an air leak into the inlet manifold, at the gasket joint at No4 inlet port?

Has the engine been compression tested when in good order?

But no, I haven't come across repeated valve/plug failure before on this engine.
-- - Pictures say a thousand words.....
Rover 25 - DL
Mark, what size engine is it?
-- - Pictures say a thousand words.....
Rover 25 - Mark (RLBS)

All comments being noted, thanks people.

Value my car