I bought an 03 disco, and it has a tapping noise. My mechanic and I thought it was a rocker arm but it's showing low oil pressure. After looking on line we saw recommendations saying that it's a design flaw and that the motor will need to be replaced. Is this really my only option?

 

it depends on what the sound is. If the engine hasn't been run dry, and it isn't a slipped liner or a cracked block, then just open the front cover (be careful. replacements aren't made for the cover anymore) and prepare to replace the oil pump. While you're in there, best to replace the any old hoses, the waterpump, the thermostat with a 180* britpart black unit, and fan clutch. These engines make a lot of noise and there isn't a one size fits all "tapping" noise. If it always taps, then odds are it could be the oil pump. If it only makes a noise when warm, then that could point to a slipped liner. You really just can't know without tearing into it, but a oil pump should be relatively cheap enough to check out and replace and then decide what to do after that. I would also check the oil pickup tube while you're at it, since the oil pan will be off anyways. While it's off, you can look up into the engine from the bottom and check the cam bearings, as they can move and cause noise as well.

I would also take it to a land rover specialist if you can. There are just too many quirks with these vehicles that really takes a trained ear. If that's not an option, you may find yourself just throwing parts at it trying to see what sticks. post a video if you can here and that might help us help you better.

 

best case replace your front timing cover and oil pump asap, worst case damage has already been done, these were common issues with the 03 model but most blew up when new or few thousand miles, i had the timing cover and oil pump replaced on my 03 as pressures were low, its a good maintenance item to do if your not to late to the pain

 

A tapping noise can be something as simple as a stuck hydraulic lifter or an exhaust leak. Do a bit of research to try and narrow down the issue before jumping to the idea that you need to replace the engine.
I disagree with the idea expressed above that "these engines make a lot of noise." After a little bit of effort, mine runs as smooth and quiet as my much newer volkswagen and honda car engines.
If your oil pressure is low and your block or liner aren't cracked (apparently less common than many people think), the front engine cover that includes the oil pump can be replaced relatively simply. As redwhitekat notes, the manufacturing error related to these parts in the 2003 model year was resolved long ago either by replacement or self-destruction.

 

What pressures are you seeing? Idle, 2K, hot and cold.

 

@mollusc is correct these engines should run quiet, but mostly at their age they do not. Old push rod V8's can tick for a lot of reasons and low oil pressure on these is very low.

The light comes on at 7 psi.

From my testing earlier this year :

Oil in use RP 10/40 Synthetic
Filter M301
Running temps between 183 - 188

I do have a tiny barely there tick hence the pressure testing

Seems good cold idle at 50 PSI idle at 188.6 ,normal hot idle, around 18 ish psi 680 RPM, Hot 2000 around 47 ish

For reference the RAVE 50 at cold idle and 10 minimum hot, it should run between 40 and 50 at 2000 + rpm hot

 

Judging by your comment that you and your mechanic looked online regarding 03 oil pressure I assume your mechanic is not a Land Rover specialist.

If you post your location maybe someone can recommend a specialist near you.

Someone who deals with Rovers all the time can save you a ton of diagnostic hours ($$$) and lots of time chasing old resolved issues like the 03 "VIN Range" problem that has long been irrelevant.

Low oil pressure can lead to ticking on any year engine. The other posters are correct, look to your oil pump first... Then make sure the oil galleys in your heads are not clogged up with sludge, etc.

Best of luck.

 

I think a myth that I see online everywhere on 2003's needs to be debunked a bit --- ie ----> "these were common issues with the 03 model but most blew up when new or few thousand miles," is just not true. They were not blowing up with a few thousand miles.

#1 -- I owned an 03 CPO from around late 2003 to 2008 or so, they don't crap out until 30-40-50-60K or more miles. Actually generally right when the warranty expired. On mine I had a ticking noise and low oil pressure that started right around 45k miles, then the engine gave it up around 60k miles. Was still under CPO.

#2 -- I worked at a high volume Land Rover dealer from 2003 to 2005 and engines were not blowing on 2003 Discos.

Someone posted about this long ago, but the reality is, it takes awhile and some miles for the oil pump misalignment to rear it's head on these 03's.

 

My oil pressure light came on a couple of months ago. I only let the engine run for a minute or so until I could safely pull it over. It started making a noise similar to what you described.

The issue was the oil pick up tube was blocked. After taking the sump cover and cleaning everything up and adding new oil the noice disappeared immediatly and when back to a quiet motor. I think there just was not enough oil getting to the rocker arms since it sounded like the noice was coming from high up in the engine.

 

My 03 had the misplaced dowel problem which appeared at 38k miles... 14 years and 210,000 miles ago. I think it can now be put to rest as most all vehicles with the issue have either died or been repaired.