Life Expectancy for 3.9L

[Drewfuss]

Anyone out there have any experience with how long the 3.9 L V8 lasts? Mine is well taken care of (I change the oil every 3000, perform regular tune ups, and put in 91 octane or higher as the manual instructs). I have about 125,000 miles on it now and it seems to run very well; even upon start-up on 10 deg F days! I don't rev it hard since let's face it, a D90 was not meant for speed anyways. Anyone think I can get 200,000 miles out of her? What about rebuilding? I don't believe it's been rebuilt yet (although I don't know a whole lot on it's history).

[Funrover]

I have 167,000 miles and still goes strong..There are others on this board with a lot more than me...

How many miles and what year is your RR?

[Paul Grant]

An engine's lifespan can benefit greatly from regular oil changes and consistant tune ups but there are other maintenence routines that need to be kept to help the engine to perform at its best.

I've owned Range Rovers that had almost 200K miles on them and they ran well. A few things need to be kept in mind, however. Timing chains don't last forever. In fact, they should really be changed every 100K to insure optimal performance. While you're doing the chain, you might want to consider changing the cam because these trucks love to eat them. Naturally, while you're doing the cam you'll need new lifters and push rods (don't forget to check the pre-load). In the end, if you are able to do this work yourself, you'll greatly extend the engines lifespan, inject new life into it as well and do it all without breaking the bank.

[TerryS]

I would like to Ditto everything Paul says, and add a few of my own opinions.
NEVER let it overheat. If you're on the highway and see the guage going into the Red, STOP and investigate; Don't try to get to the next exit. Overheat a Rover block can, and usually is fatal. I have learn to not trust LR electric temp guages and would always change them to a mechanical, capillary type. This type rarely fails, is more accurate, and reacts more quickly.
When (not 'if') you change your timing chain, change both sprockets. The crank sprocket is steel and will far outlast the cam sprocket, which is a diecasting with resin teeth. You don't have to spend the extra money for a double rollerchain set (aftermarket)
The case depth of the nitriding to LR cams is quite shallow, which is the primary reason they wear so badly. 75k and you can be pretty assured it is worn some and you're not getting full lift on either intake or exhaust. Reduction in performance is hard to notice, since the 3.9 isn't a powerhouse to begin with. When you pull the intake manifold to replace the lifters (always use new lifters with a new cam), have your injectors cleaned and checked. There are Bosch service centers all over the country.
Oil pump bottom plates wear also, so have it resurfaced or replace it. The gears don't seem to wear significantly, but the pressure drop from a worn bottom plate can be as much as 20 psi.
I swear by Mobil One, Castrol Syntec or other high quality Synthetic engine oils. Unrelated to the engine, but on that note, changed your R380 lube to synthetic ATF also. The gearbox will run a bit cooler with synthetic.
While on the subject of the transmission, consider adding an external engine oil cooler. R380s run very hot, and the engine oil cooler, being in the radiator (right side) tank, just makes keeping the engine cool that much more difficult.
Change your antifreeze often, at least annually. It's cheap compared to a sludged radiator, or worse, and overheated engine. Always run 50/50 water antifreeze, no more, no less.
The 3.9 is very rebuildable and provided you run good fuel, you can rebuild at 125-135K with out reboring, but the sleeve are fairly thing so don't figure on ever going beyond .020 oversized. If you get to that stage, use an American mfd ring set, such as Perfect Circle. They have better oil ring and the scrapers are much better defined than UK 'genuines'.

[Paul Grant]

Terry,
I just recently went from using Mobil One ATF in my LT77 to Red Line MTL and was really pleased with how much better the transmission shifted. I was in a conversation with a number of blokes on one of the UK Rover boards and was told the primary reason that Land Rover recommended ATF for the manual transmissions (LT77 & R380) was to make it easier on the blue haired ladies driving their Rangies on cold winter mornings. I did a little research only to find that Land Rover changed their recommendation of ATF to various MTL's back in the late 1990's. The Red Line MTL came highly recommended so I gave it a try. The difference was like night and day. Keep in mind that with all the stuff I've done to my truck the only thing original is the LT77 and with just under 120K miles on it I have my fingers crossed hoping to hold off a rebuild a little while longer!

[Drewfuss]

Hmmm... sounds to me like I'll be pulling things apart under the hood sooner than I thought. As I said, I'm at about 125,000 miles right now, and everything is still running well. Due to my circumstances, I'd say I'll have the ability to perform the items mentioned next year. I have to finish my YJ (needs to be painted since I turned it into a CJ7), then I can drive the jeep around while wrenching on the rover. Most likely I will do all the work myself so I should probably break down and buy a shop manual finally (I've gotten by so far just using that thing between my ears and my previous back-yard-mechanic experience).

[Bracco]

Not sure about the 3.9, but I have a 1985 110 with a 3.5 and it will hit 225K this week. Burns a quart of 20/50 every 1000 miles or so. Plan on re-building or replacing it with a 3.9 in the fall. It is regularly maintained and has no major issues although she is a little sluggish when the temperatures are low and she wants to warm up a little before getting underway.

[Muddy Oval]

We routinely see 3.9's with close to or exceeding 200K. I don't think I'd go to all the trouble to freshen one up without replacing the bottom end bearings though. I have a dilemma with my Defender. It needs a new distributor which is no biggie- a Mallory is going in soon. The timing chain should probably be done, but then the oil pump might as well and then the cam... lifters, water pump, then why not do the heads while it's apart. It's a slippery slope once you tear into it. I think I'm going to force myself just to drive it until it NEEDS intervention instead of tear it apart and patch up little things when in the long run, it's still a high mile engine with some new parts. Those new parts are no consolation when the compression is low and the bearings wear out.