Discovery 3.9 or 4.0?

[Casey_leonard]

Hi All,
I often see Disco's advertised with either a 3.9 or a 4.0 litre engine. is there any difference between these 2 engines.

Cappy

[TuffRR]

There are differences but not what you'd expect. They both have the same bore and stroke so technically they should both be called a 3.9 or 4.0 depending on whether you are rounding up or down.

The big difference is in the cross bolted mains in the so called 4.0 which first appeared in P38 Range Rovers, and Series II Discovery's. They also differ with belts (serpentine vs a lots of v belts). There are a few other minor differences as well.

Due to the cross bolted mains, the "4.0" is more suited to supercharging etc due to increased strength.

Basically, if its in a Disco I its a 3.9, if its in a Disco II its a 4.0.

[Casey_leonard]

Thanks TuffRR
Do you know the year that they changed in the disco. I am looking at a 1999 model here in Aus, that's just advertised as having a V8i. I guess I can look under the bonnet and see what belt arrangements it has, but knowing in advance mat save me a trip.

Cheers
Cappy

[TuffRR]

Disco II came out in 1999 although i have seen some dealers advertising the series I as a 1999 also. I'm not sure which month is the cut off.

Chances are it's a Series II so will be a 4.0. I assume you can pick the external difference between the Series I and II?

[Philip A]

AFAIK, the 4litre does NOT have cross bolted mains.It has the bosses and the improved bearing caps, and the larger diameter crankshaft, but only the 4.6 has cross bolted caps.
Regards Philip A

[up2nogood]

Best way to pick between series ones and twos is the door handles.

Series ones are flush with the door panels and the series twos are a more conventional protruding handle.

Pretty sure you can get a 3.9 with serpentine belts, so if you want to be sure about getting the 4.0 go the door handles.

[TuffRR]

Lol, the difference between 3.9 litres and 4.0 litres is the door handles.

Actually, the more i think about it i think the late 3.9's did have serpentine belts. In either case the vehicle is either Series I or II, pretty simple!

[up2nogood]

So door handles aren't a good way to pick between S1 and S2 and, therefore, 3.9 and 4.0?

I would have thought given the S2's are the first time a Disco saw a 4.0 it would be a great way for a newbie to easily pick the right car.

Oh well.

[TuffRR]

I would have thought given the S2's are the first time a Disco saw a 4.0 it would be a great way for a newbie to easily pick the right car.

Oh well.

That's what i thought!

[MJP]

Hi Guys,

I have a 96 V8i Disco S1 and it has a serpentine belt.

Mark.

[Casey_leonard]

Hi All
I rang the guy this morning and he confirmed that it is a 4.0 engine.
I did look at a 3.9 over the weekend that had sepentine belt though, it was 1996 model.
Thanks you all for your input, great forum.
Cappy

[up2nogood]

Don't forget the door handles!!!!!

[Casey_leonard]

Just got back from veiwing the vehicle and it turns out to be a ser 11 and yep those door handles are the extruded type.
I ended up doing a deal and pick it up next week.
Cheers
Cappy

[Loanrangie]

4ltr V8's DO have cross bolted main caps.

[up2nogood]

And good luck, Cappy!

Plenty of ideas on here for mods and strengthening your P&J.

Cheers,

Alex

[PK]

I have a 1999 Series 1 - first reg'd June- with serpentine belt.
Easiest way to pick series 2 is rear tail lights - series one are low, series 2 are half way up to the roof.
If I had a series 2, it would have a manual centre diff lock fitted straight away.......

[Casey_leonard]

So the ser 11 centre diff lock is auto, (damn missed that one), how, when, does it work, do I 'need' to convert to manual.
Seems I have a bit to learn.........
Cappy

[TuffRR]

D2 centre diff lock is not auto. It does not engage at all unless an aftermarket kit is added to manually select it. Land Rover in their wisdom decided that Traction control was superior to the CDL.

Being a 1999 D2, your transfer case is compatible with the CDL kit.

[Casey_leonard]

Thanks TuffRR
Does that mean that all ser 11's have traction controll and would CDL be able to co-exist with it.
Thanks
Cappy

[TuffRR]

AFAIK, all D2's have traction control. CDL in conjunction with TC does work well in a number of situations. There are other times when you do not want the TC at all. I think with the CDL kit you can determine when the TC comes on, something about starting the vehicle with the CDL locked???

Again, perhaps some of the D2 guys can chime in, I'm just a lowly D1 driver.