tappits rover 25?

They are hydraulic on all engine sizes fitted to this car, so they are self-adjusting, if they are making a noise, one or more of the hydraulic lifters maybe stuck/seized or the camshaft is badly worn!! you could try putting some flushing oil into the engine and follow the instruction on how long to leave it in for then drain the engine and refill with a good quality oil and new filter as sometimes the old oil will gumm up the lifters, leading to the noise

nigel
October 2010