Is the design of the 3.9/4.0/4.2/4.6 inherently bad?

[dallas]

I agree, I have 280,000 km on a 2000 D2 original engine, original head gaskets, run on dex cool and no problems. Always used synthetics and followed maintenance intervals. Just developed a small oil leak in the front cover so I will swap timing chain and gears and put in a new oil pump. The problem with dex cool was the gaskets used in some GM's as long as its changed in time I believe it's fine.

Yeah...the plural of anecdote is not data, and dexcool is not what kills these motors. I will agree that dex tends to turn acidic faster when there is air in the cooling system, and the D2/P38 cooling system is problematic to bleed so this is more of a factor......but it's not the problem.

That's great that yours runs well. But like I said before, tolerances were little better than luck at some point as the tooling was obviously worn out and not being maintained towards the end of the line of these motors.



OK....I'm not even sure why I responded to you with any sort of though when you are just trying to be inflammatory...but whatever.




That's not just your theory, it's a fact. They were run hot for emissions and to juice the last bit of performance they could get out of them (on the cheap) the attempt to be competitive with modern offerings. There is no excuse for the different between "normal operating temperature" and "oh ****, I just melted a piston" to be as close together as they are on the Bosch motors other than a massive compromise for something that should have been replaced long ago.

 

[Douglas S.]

D&D Fabrications. Mark there knows more than just about anyone in the US about these engines and does full service machining and parts on them.

Mark re-built the stock 5.0 in my dad's RRC. Had some not so insignificant issues...had to be sent back to be fixed, but all seems to be good now.

I certainly agree with the assessment that nobody in North America is more familiar with the Rover V8 than Mark is.

 

[RangeBrover]

Sounds like its time for an LS1 swap. I've got one and a T56 sitting in the garage if you're interested, always thought a d1 with this setup would be a great combo.

 

[m3 bavaria]

North Dallas Rovers has been encouraging an LS swap. Seems spendy though...

 

[proper4wd]

Spendy and a huge headache. There is nothing wrong with the factory set up, just fix it properly and you will have a good, reliable vehicle (so long as it is well maintained).

 

[David Harris]

Spendy and a huge headache. There is nothing wrong with the factory set up, just fix it properly and you will have a good, reliable vehicle (so long as it is well maintained).

Yes. The more you look into these swaps, the more time and money you realize it will cost and the better a well maintained Rover V8 looks. . . A Land Rover can be a very reliable vehicle if you put the effort into addressing its weaknesses. There's really none that can't be overcome. You have to really want to own and drive a Rover to achieve this though. Rovers select their owners, not the other way around. . .

 

[proper4wd]

Very well said!

 

[TheSweetness]

Yes. The more you look into these swaps, the more time and money you realize it will cost and the better a well maintained Rover V8 looks. . . A Land Rover can be a very reliable vehicle if you put the effort into addressing its weaknesses. There's really none that can't be overcome. You have to really want to own and drive a Rover to achieve this though. Rovers select their owners, not the other way around. . .

Is there a thread on addressing the weaknesses? I don't want to highjack this conversation, but if you can point me to some information that would be great. The Disco runs well now, just want to avoid failure out in the woods if possible.

I've scoured the other forums, and this one, but there are more threads on the countless things that fail and not a common repository for major problems. My assumption is the answer is "purchase an ultra gauge" and monitor temps, and fix as needed...

Thanks, Michael

 

[David Harris]

Is there a thread on addressing the weaknesses? I don't want to highjack this conversation, but if you can point me to some information that would be great. The Disco runs well now, just want to avoid failure out in the woods if possible.

Thanks, Michael

I can't think of a recent one just on this, but it would be a good one. Why don't you start one?

David

 

[yehsure]

Wabi-sabi

Yes. The more you look into these swaps, the more time and money you realize it will cost and the better a well maintained Rover V8 looks. . . A Land Rover can be a very reliable vehicle if you put the effort into addressing its weaknesses. There's really none that can't be overcome. You have to really want to own and drive a Rover to achieve this though. Rovers select their owners, not the other way around. . .

Thank You for saying this! I've been slowly coming to the same conclusion. There are a lot of great products out there but just finding the right one for you is the trick.

My D90's previous owner swapped a 4.6 for the 3.9. Very peppy but requires constant attention to detail, particularly cooling. But for some reason, I kinda like it. No, I'm not being honest, I love it. I like to think that nobody understands her like I do... even if it is because she's a bit of a Frankenstein. I guess if I wanted a balance of highly capable, reliable, safe and fuel efficient, I'd drive a Toyota. (not intended to insult- I'm being literal. Toyota's are awesome for the right application).

 

[GaAlpinaowner]

Who is a good 4.6 builder?

As mentioned D&D
CannibalV8
Great Plains Rover
Turner..
They are all in Cahoots with each other in some form or fashion....I just spec'd a Cannibal Longblock myself.
I will keep my opinion on the Stock 03 4.6 to myself ....:ar15:

 

[m3 bavaria]

Excellent post.

 

[Frontier Phreak]

That's not just your theory, it's a fact. They were run hot for emissions and to juice the last bit of performance they could get out of them (on the cheap) the attempt to be competitive with modern offerings. There is no excuse for the different between "normal operating temperature" and "oh ****, I just melted a piston" to be as close together as they are on the Bosch motors other than a massive compromise for something that should have been replaced long ago.

Got any evidence to back that up as fact?

No engine can pass emissions unless it idles and cruises at 14.7:1 +/- 0.2. It must be so in order for the catalyst to function properly. If they were truly running lean, they would emit excessive NOx, and then they would fail emissions testing. These engines do not run "lean" under any normal condition. Now, do they run lean at full throttle? I've never tested it, but I doubt it. If they ran leaner than 13.5:1 at WOT, they would likely explode very quickly due to detonation. And no emissions testing is done at WOT, and therefore no benefit to running "lean" at WOT.

They do have a warmer thermostat. This was done for fuel economy, not emissions. Running the engine hot has a very minor effect of making it produce more NOx, but this effect is extremely minor compared to the fuel mixture. Running the engine hotter does have an effect on economy, though not a lot in the grand scheme of things, on the order of 0.1 mpg or even less.

As for the rest of it, Disney got it right. It's the worst engine ever made. Anybody who disagrees is kidding themselves. It would make a really sweet engine for a lightweight British sports car that is never far from a tow truck or trailer, but it's got no business in a truck with the capability of a Rover. But this goes for ALL the variants of it, not just the 4.6L. A GM pushrod V6 would make a better engine for this truck.

 

[proper4wd]

It's the worst engine ever made. Anybody who disagrees is kidding themselves.

You're a profoundly intelligent individual whose self-evidently truthful and unbiased opinion I will hold in the highest regard.



Or am I kidding myself again?

 

[Oilburner]

Come on...

- Need for 89 octane or higher (what were they thinking?!?!)
- Sludge in cold climates
- Oil cooler lines that leak (and catch fire)
- They slobber oil all over themselves like a detroit diesel (and catch fire)
- Easily damaged if overheated (may catch fire)
- Cooling system needs a lot of attention (see above)

I am not a GM fanboy but a 1990s TBI 4.3 V6 puts out as much usable power as a 3.9L V8 with half the fuss on 87 octane for 300K miles. A vortec blows it out of the water, and we're not even into V8s yet.