Thread: Engine Numbers - 3.5 EFI and 3.9 EFI

All factory 23D prefix engines were 3.5 EFI

the Land Rover/Range Rover factory 3.9 engines had prefixes:

• 30G00001 Land Rover Defender Japan 9.13:1 EFI
• 31G00001 Land Rover Defender 50LE 9.13:1 EFI
• 35D00001 R.R Disc efi Man 9.35:1cr 1988 onwards
• 36D00001 R.R Disc efi Auto 9.35:1cr 1988 onwards
• 37D00001 R.R Disc efi Man 8.13:1cr 1988 onwards
• 38D00001 R.R Disc efi Auto 8.13:1cr 1988 onwards

What you may have is one of the unstamped (warranty) short 3.9 engines that someone has fitted in place of a 23D engine and re-stamped the 3.5 number onto the new engine.

The only way to tell for sure is to take the heads off.

Early 3.9 blocks (<Jan 94) has more ribbing on the outside and 14 bolt heads (if original). Later 3.9 blocks (>Jan 94) had bosses cast into the block sides to allow for future cross-bolting of main bearing caps, more and different ribbing than earlier blocks and 10 bolt heads (if original).


So, depending on the age of the block, the external block ribbing will indicate the major difference between 3.5 and 3.9.


Perhaps this may help.


Cheers


Pete

Both motors are still in the cars but from what I can see through all of the crust caked onto the '3.9' block it is visually the same as the very clean 23D 3.5. It has 14 bolt heads, which I haven't removed yet but I will take one off this evening. It is a V belt too, which I didn't bother to mention as it is obviously not a late 3.9. I'm not fussed if it is a 3.5 or 3.9 I just want to know what it is for later reference.

I mainly want to know so that I can find out why it has 3.9 stamped next to a 3.5 engine number, which is quite odd. The motor was recorded and registered up until around Christmas, when the car was taken off the road for extensive rust repairs.

So I finally got around to pulling a head from the motor in question, it's a 3.9. It also returned 170psi on each cylinder from a cold compression test, has reconditioned and ported heads, possibly a long duration cam, new lifters, pushrods, rocker arms, valves and valve springs, over-sized pistons and fresh hone marks on the liners. The inside of the heads is almost spotless, the valve stems/rocker arms/rocker shafts etc are a nice shade of bronze as is the top of the block and the cam lobes are almost mirror-like with no wear marks at all. Doesn't look like it has top-hat liners though, pity.

Were blank 3.9 warranty motors common?

If it had the "knobs" on the side of the block where cross main bolts would go on a 4.0 or 4.6 then the block is a 3.9.

Likewise you could have got an idea of the bore by removing the sump and measuring it from there.

Probably no need to pull the heads unless there was another reason.

I guess that maybe I should have looked at the thread a bit earlier.

Cheers

Garry

Hindsight would have poured and measured oil into the cylinder.
He also should have looked at the thread earlier.

The warranty motors exist for all models, just not many escape.

Given that your's seems to have had extensive work on the heads, I would suggest that it started life as a 3.5 and was "worked" later with 3.9 components. The 3.9 stamp is to advise anyone working on the engine its a 3.9 and not as indicated by the prefix.

I would always choose a 3.9 over a 3.5, the 3.9 is the engine the Range Rover should have always had (as a minumum)