4.0 v8 ticking/tapping noise when warm

I have a 2003 4.0 v8 that has started making a ticking/ tapping noise from engine when it gets warm after about 20/30 mins of running. It sounds like a loose tappet but comes and goes. While it's doing it it may last 2 mins then go away for 10mins but when it's there it's quite loud and noticeable. It only seems to do it on idle but I'm not sure if engine noise drowns it out at higher revs.
I've read about all sorts of possibilities from lifters to liners but not sure if my engine has all these thing...
Oil and filter have been changed to see if it made a difference but no luck.

Any ideas before I call the garage?

tappet,exhaust manifold gasket, cylinder liner are common possibilities

What causes the liners click?

ian27 said:

What causes the liners click?

Click to expand...

cracked block, but some coolant loss as well a symptom

Loose rocker tips on early engines, or rocker itself worn on the shaft, they are ali rockers running direct on the steel shaft.

Late V8 should be OK, but service history is important and the correct coolant is VERY important.

We had a similar thing with ours, once we had run it on diesel oil for a few thousand miles is gradually died down and stopped, so probably some goo in the lifters.

Peter

Start the engine from cold, start a timer at the same time. When the ticking comes in stop the timer.

99% certain that if you do the same the next day the tick will start at the same time which mean loose liner / cracked block.

Sorry for the bad news but better know straight away rather than spending money on other parts.