My 2003 Disco that the wife drives has broken another rocker arm on the #4 intake valve. This time it only lasted 2k miles before the tick came back. Inspecting the connecting rod it looks ok. I'll have to tear the engine down to get to the tippet and cam shaft. I suspect something worse at play. #4 has also had random misfires at times. Normally at idle. You can feel the skip when you put your hand on the exhaust. The SES light will come and and after a few restarts goes away on its own.

This engine was replaced a few years ago by the previous owner and has 30k miles on it. Been annoying to say the least.

It'll take me awhile before I can dig into this engine so it'll be in storage for now. But my thoughts are on either rebuilding this entire engine with top hat liners, and improved internals, if there are such a thing. Like a better cam? I have kept most of my Rovers stock so I haven't seen any good aftermarket builds. Or just go full retard and yank the 4bt Cummins out of my van and shove it in there. I'd love to use the Land Rover Diesel but escaping emissions laws would be to much of a PITA.

Any thoughts? I'd like to keep a Rover engine in the rover.

 

You can get upgraded Cams from Crower, and Kent Cams. There is a Crank to make it 5.0 if you are feeling real saucy. RPi sell ported polishe heads with larger valves as well.

 

I had a broken rocker caused by a spring that wasn't seated in its pocket 100%. It was hard to see and I was baffled until a co-worker looked close enough to see it-I was blinded by lack of outside-the-box thinking. The spring was being fully compressed and caused the rocker to break instead of bending the push-rod like you'd think.. I had just done head gaskets and refreshed heads myself and just missed it in my hurry to get it all back together. Pushed the spring back into place with screwdriver, replaced rocker, done. The only other thing I can imagine that would cause that would be a clogged/charged lifter(tappet) which I would think would also bend the push-rod, but I guess these aluminum rockers are the weak link.. good luck.

 

Yeah, you have something wrong in the valvetrain. Valve spring seems feasible, could be a seized lifter. If the heads were cut too much that could be it. With the lifter at maximum lift you should be be able to get some additional lift without binding.