Land Rover Repair: 2000 Disco II petrol, mileage engine, lubrications

Question
I purchased the car in 2003, I started to here a slight tapping sound coming from the engine occasionally, I took it to the dealer who said it was noisy lifters not to worry until it gets bad, bring it in and they will fix it.
About a week later it got worse I took it back, they found sludge in the oil pan so they cleaned it out, ran the engine for a while the noise came back, they concluded I needed a new engine, the car has 43000 miles on it.
I have had the car sit in the driveway idling for about 15 minutes, it sounds fine but when I pumped the gas, the tapping starts and will continue until you turn off the engine let it cool, pumping the gas seems to shake the engine which starts the tapping.
It is not a consistent tap when idling, it will tap a couple of times stop sound normal start again, stop. Once you are accelerating it sounds consistent.
The dealer had just changed the serpentine belt, a couple of weeks before it started and also after they cleaned out the sludge they gave me back the car with 2 pints to much oil in the engine.
Thankyou any input would be great thankyou Kerry

Answer
Hi Kerry,

I once had some tapping noise after filling up at a new service station in our area.  Seems the attendant put 87 octane in the tank instead of 91 octane.  Noise started slowly and became worse.  I check the receipt and noted that regular gas was used and thus the noise was spark knock. Nothing too serious and the next tank corrected everything.

Could this be your problem?

IF your dealer is saying replace the engine because it's knocking...maybe you should get a second opinion.  It could be sticking exhaust valves (a common problem with series II Disco's) that usually arises between 50k and 60k.

Maybe all you need is a valve job.  It's still expensive (~$2500+) but it far less than a new engine.  

So long as you've maintained it properly, have not abused the engine (overheating, no lubrications) I find it odd that a low mileage engine should need to be changed.

I'd find a european specialized mechanic and get their opinion on the subject.  Don't mention the diagnosis made by the dealer, you wouldn't want to influence the 2nd opinion.

Best of luck,

JohnMc