This write up is for my 03' which is in the death range. I've had a tick for about a year or so. I place no more then 4K a year on this Disco so I haven't had the energy to tear into it.

The noise had become so annoying that I had to do somthing though. Oil Pressures at Idle hot 11psi/2000-2500 40-45psi.

The noise sure sounded like it was coming form the valve train. Started taking the intake off to expose the valley and all looked good with cam and lifters.

Decided to go into the oil pump so I dropped the oil pan to disconnect the Oil pick up and removed the Front Housing. I think I found the source of my tick (See Pictures). The Oil Pump was cracked in three place as I believe Buzz has posted before.

I really dodged a bullet on this one since I've been driving it for over a year with this cracked.

At least I saved from pulling my engine this time around.

 

I've had my oil pump, etc replaced and still have the tick.

I'm in the process of replacing gaskets from the Valley up, and think I finally found my leak (the valley end seals were brittle and cracked, in addition to the bolts being loose). I don't believe this will fix my tick, but everything looks ok inside.

I know the timing chain, oil pump, housing, etc. are in good shape, so hopefully your tick goes away after your repair, mine didn't

 

I have also changed the oil pump and it made no difference in the tick. Its the liners moving around, you can chase the noise forever or live with it unless you have the cash for a nice top hatted block.

 

Did both of you also have cracked pumps? I was sure hoping this was the cause of the tick. If I pull the heads I should be able to see some marking in the firing ring if it is a sleeve correct?

 

Exactly.

With a cracked oil pump as long as the oil PSI is good there is no problem, if the oil pump were to come apart the oil light would come on, you would shut the engine off.
Then you replace the oil pump and are good to go.

 

Next time you drop your oil pan unbolt a rod cap and slide out both portions of the bearing and inspect. Pay close attention to the rod bearing closest to the piston

 

Well I'm swapping blocks with my spare 04'. Don't want to take the gamble.

I'll let everyone know how the firing ring looks after the engine is out. Not much more to go.