I just want to share my basic observations from working on my 1997 Discovery 1 LSE V8i (USA version).
I purchased this truck few months ago, with only 132k miles on the clock.
D1 was horribly neglected by the previous owners. To give you the idea:


I started with cleaning the top of the engine and working my way to the bottom. I replaced tappets, re sealed everything and moved to the front of the engine...I'm honestly shocked that timing chain was functioning at all, I posted video how loose it was at the D1 Facebook group, but here is screenshot (chain was flopping left and right - no resistance at all).


I replaced also oil pump gears and water pump while at it. At that point I decided to add "sandwich" plate to the oil filter and place oil pressure gauge inside the cabin

For those who geek out about numbers, with Valvoline 5w30 (restore and protect), I was getting 29 psi at 2500rpm when engine is at normal operating temp.
Per Rev manual, At a steady engine speed of 2500 rev/min - engine oil pressure reading should be - 39.8 psi. I know that i'm not within the spec on my front cover and oil gears in one spot (that's going to be corrected soon, i just had a hard time finding D1 engine front cover).
Just for kicks, i switched to Castrol 10w40 and that resulted in slight boost in oil pressure (roughly by 3 psi). My hot idle is at 15psi, so i'm not tripping oil pressure warning light, but I'm only at 32psi at 2500 rpm. So, this will have to get corrected in the future.
I have also completely overhauled suspension, because dampeners were completely gone...I went with OME - no lift solution and quality of the ride is amazing now.
I still have to change radiator, because of small leaks in the driver side upper corner. I already changed all the oil cooling hoses and still have to change AT coolant hose, because there is a leak there as well...If anyone has good suggestion which radiator to purchase, i'm all ears.
For now, engine on my D1 is not leaking anything, so it's actually shocking to see it stain free floor in the garage, lol!
Also, compression test produced following results:
Cylinder 1: 176psi
Cylinder 2: 179psi
Cylinder 3: 176psi
Cylinder 4: 168psi
Cylinder 5: 170psi
Cylinder 6: 170psi
Cylinder 7: 170 psi
Cylinder 8: 176 psi
That's after all work and running for 100 miles.
Overall, I think D1 4.0 is not bad all. I'm convinced tho, that lack of basic maintenance (timely oil changes), absolutely contributes to many problems with those cars...amount of the sludge i removed from my engine is just scary and I know that I couldn't get everything out.
I'm hoping that frequent oil changes will eventually help to clean this motor...time will tell.

Let me know please if you have any questions, and I will try to help as much as i can.

 

Love it. You may want to put this in the 'build threads' section to keep on ongoing chronical of the journey.

 

Pretty nasty inside. Glad you did your magic to it. Compression numbers seem pretty good. Sounds like you got a decent rig. Given the miles, I'm surprised you didn't pull the heads while you were in there and put on new head gaskets? (or maybe you did)

If it makes you feel any better, my Hummer H3 has about 10-11 psi at idle and 26psi going down the road. It's been what way probably for 8-9 years?? Maybe longer with the PO. Sun still comes up in the morning. One of these days I'd like to rebuild it. I think I remember seeing 10W-40 oil recommendation in the owners manual ....if I remember correctly.

I wonder if your engine has some sludge on the oil intake?

 

I might need a new radiator too, if anyone has recent positive feedback...

 

I hear you Mark. Reason i didn't dig into the heads yet, surprisingly truck holds temps extremely well. I'm running it with the external scanner, so while driving, temp hoovers around 176F (!). So when cleaning everything out, I checked for any leaks on heads, couldn't see any, so I went with the "if ain't broken, don't fix it" approach. Also, honestly, after few oil changes, I want reopen rocker covers anyway to see how we are doing with the sludge, to make sure all is staying relatively clean. Worst case, I will then rip everything out and do camshaft, bearings and heads and front cover machining at once...we will see. So farm this Disco is a fighter, so i will keep it in the fight as long as i can, ha!

@10W40 - yes, it's in the manual as an acceptable oil for US "petrol" engines

 

I run 15/40w Rotella Dino Oil or Royal Purple Full Synthetic oil in all my D1/D2's. Radiator wise DO NOT and I repeat DO NOT buy a Nissens RRC/D1 radiator. They used to be the go to radiator for these as the brass tank ones are $$$ or not available. If you have a good radiator shop take and have your original radiator re-cored/repaired or plan on $$$$ for an Allisport Aluminum Radiator. With the Tariff's I was sitting at 1800.00 USD shipped to my house. The Allisport did simply drop right in and works flawless so you do get what you pay for IMHO.

 

Shooot! I was quietly hoping that those would be good. Thank you for the warning. I'm surprised that mishimoto isn't making radiators for our Discos. I used their radiator on my 1984 FJ60 and it's working awesome, but they got nothing for Land Rover Discovery...I have two local shops which possibly can fix / recondition radiator, i will have to check with them. Worst case, I will bite the bullet and go for the Allisport like you are suggesting, but ooof, that's a lot of money for the radiator...

 

Quick question. By miracle, my audio head unit came back to life. I never got the code when I purchased the car but today i was just randomly pressing buttons and CODE switched to TAPE. Wow...awesome, but i don't have any tapes anymore...all buttons work now, volume, fade, balance and etc, with the exception of the BAND...all i'm getting is either TAPE or Weather Band radio...ugh...on FM or AM Radio...any ideas what to do?

 

I had hopes of having my factory radiator rebuilt locally here but that did not work out…. Thus I wound up buying a Nissens radiator instead. Installation was uneventful and it fit fine. Definitely helped the consistency in my coolant temps. It’s been a few months and so far it’s holding up. Still keeping my original radiator if I can find a place to rebuild it at some point.

 

Be warned when summer comes to keep any eye on the Nissens Radiator. 4 close friends this year (including myself) all had their RRC/D1 Nissens Plastic Tank Radiators fail!!!!!!! 210-212F was the fail point (in traffic on the trail). All 4 died from the exact same wound in the exact same spot..... Drivers side top left back of the tank split wide open with a 5inch gash/opening..... Everyone including myself contacted Nissens as all our Radiators were under a year old & we got absolute silence from them. Rock Auto even pulled them from their website and so did Worldpac. That right there tells you something is up!!! I tried to buy a Ron Davis Aluminum Radiator, but they never gave me any specific details if it was an exact OEM fit or not. I'm not going to blow up my perfectly fine running V8 due to some cheap radiator so I contacted Allisport and they had a 8-10 week back order on radiators. I asked if it was 100% OEM fit and they said absolutely so I went ahead and gave them all my info and got put on the list. Well 5 days later I get an email my radiator was ready so I quickly paid them, and I had a customs/Tariff email via DHL in 1.5 days. Paid that and had my Radiator on my front porch the next day. Allisport & DHL don't mess around! Next day I installed it and everything went back on like the OEM radiator. I wouldn't hesitate to buy another one from them. Great customer service, great shipping & handling (it was packaged so so well), and a fantastic product.