Rebuilding a Series II Disco V8 Engine

[CBR]

Hi Guys,

I'm new to this forum, but were a member of disco2.com many moons ago (before it got hacked to pieces!) (I have also posted this topic on lro.com, but so far no responses.)

I own a 1999 Series II Disco V8 ES (A) with 270 000 km on the clock.

It suffers from a persistant misfire (that clears after a few seconds of elevated engine speed running) when the car is started after being switched off for a few minutes and a constant loss of coolant fluid. We have determined that coolant fluid is leaking into the Number 6 combusion champer (most likely source is from behind the cylinder sleeve, up over the top of the sleeve and into the chamber - the head gaskets were replaced about 10 000 km ago and the cylinder heads machined and pressure tested and found to be good). Ironically, the head gaskets were replaced BECAUSE of the loss of cooling water was blamed on a blown head gasket by the workshop I normally have my Disco serviced, etc. They failed to either check for or notice anything wrong with the block when they had the cyl heads off.

I'm fairly mechanically minded, so I have decided to tackle the engine rebuild myself as a home project. With this in mind, I have a few initial questions:

1. I have bought the LR Overhaul Manual for the 3.5, 3.9, 4.0, 4.2 & 4.6 V8 engines (Publication Numbers: LRL 0164 and LRL 0004), ISBN 1-855-20528-9. When I furchased it via the net, I was under the impression that it covered my car's engine. When I got the book, I noticed it was written in 1997/1999 and only covers the following:

3.5, 3.9 and 4.2 litre engines (with or without "B" engine number suffixes) fitted to Discovery, Defender and Range Rover Classic (Publication LRL 0164)

4.0 and 4.6 litre engines with Prefixes 42D, 46D, 47D, 48D, 49D, 50D and 51D fitted to "New Range Rover" (presumably the P38A), Discovery (NAS) 1996 MY onwards, Defender (NAS) 1997 MY onwards, Defender V8i Automatic. (Publication LRL 0004)

My Disco's engine number prefix is 55D.

Questions:

i) Can I use the LRL 0004 document in rebuilding my 55D engine?

ii) Is there a overhaul manual for the 55D engine? (I can't find one using Mr Google)

iii) What is the difference between the 55D and the other "D" engines listed above?

iv) Was the Series II Disco ever fitted with a 4.2 litre engine? (I've heard that the facelifted V8 (approx 2003 MY onwards), was a 4.2)

2. I was informed that the V8 engine's main "vulnerability" that prevents it from having a near infinite life, is this tendancy to have the cylinder sleeves "pull away" from the cast alu block and causing this sort of water leaks (mine leaks only into the No 6 combustion chamber. Engine oil shows no signs of water contamination).

Question:

i) Is this true? (Is this problem really so "common"?) (Or is someone trying to BS me?)

ii) Can such a block be effectively repaired? (New Liners fitted, etc) (I have also heard of companies fitting liners from a 2.0 litre Isuzu engine and having good results)

iii) What are the best non-OE pistons to fit? I've had varying success in finding out of Piston Manufacturers like Mahle, ATE and Kolbensmith produces aftermarket pistons for the 55D engine?

iv) Considdering the answer to (2-i) above is "YES", what is the leading cause for this mode of failure? Less-than-ideal cooling on the rear cylinders? Lean running conditions? (I had a UniChip fitted to my car about 50 000 km ago (at the time, it had no misfire/water consumptions problems) and it definately improved fuel consumption and my guess is the engine is running a bit leaner with the chip). How do I know if my engine is running TOO lean? (It still only gives around 6 km/l when driven sedately)

3. What items/areas are critical issues/pitfalls that one must be carefull of when rebuilding the 55D engine?

I know I've asked a lot of questions, but any help/information will be GREATLY appreciated!

Thanking you in advance!

Chris

[geoffbeaumont]

I don't know what engine the earlier Disco 2s had, but I'd guess the 4.2 in the later ones is a Jaguar derived lump rather than a Rover V8?

Judging by several previous discussions on here (I'm no expert myself), the infamous slipped liners and porous block problems with the RV8 are actually pretty rare. I'd have though in either case the cheapest solution would be to get a replacement block from a second hand engine. RV8's are cheap as chips, and all standard engines from 3.9 up have the same bore - however some of the later improvements such as cross-bolting will be absent on older blocks. Check with a grown up before you take my advice on that!

There are plenty of other things that limit the life of an RV8, if you want them to last they'll be needing a full rebuild by about 150k as things like the bearings and cam will be in the way out. If your head gaskets get to this mileage then you've done incredibly well. It's fundamentally a sixties engine, remember! The only way an RV8 would go on for ever is the same way the rest of the land rover does - because masochists like us keep fixing them...

[BogMonster]

Same engine as mine, though mercifully my coolant leak is a dodgy front cover gasket which is about to be changed.

Geoff the engine is the 4.0 version of the V8 (still 3947cc though!) with the Thor inlet manifold and Bosch system, still a Rover V8 right to the end of the Discovery 2 - only the Discovery 3 has the Jag motor.

CBR you may wish to check out www.landrovertechinfo.com for technical information but I don't think there is an overhaul manual suiting the later engines, the one you have is for the earlier 3.9 V8 which is basically the same engine in terms of dimensions but there are quite a few detail differences not least of which are the entire intake system, fuel injection system and ignition system.

If mine ever went bang I think I would get a rebuilt engine from Turner Engineering and be sure I could forget about it but as I only have 37000 miles on mine hopefully it will be good for a couple of years yet

[CBR]

Hi Guys,

Thanks for the feedback so far. I haven't had time to update my profile (and I did not mention it either), but I reside in South Africa. Unfortunately, (over here) Rover V8 parts are not so easy to get hold of (nor as cheap) as in the UK!

Hmmm, I was hoping that the overhaul manual that I bought would be of more use, but I suspected I was going to be out of luck (let alone the fact that the Thor intake system is significantly different than the earlier engines).

[Ally V8]

Any,(and alot of) the 94mm block Rover v8's can suffer this problem,there are many theories as to why it happens.The ones that blame lean cruise mixtures I think are rubbish - I've spent too much time driving them and watching the oxy sensors switching to believe it.Alot in the UK get killed by LPG systems not being capable of correct fuelling,they tend to go lean rather than rich.The other thing is the cooling system being marginal in the first place and owners not checking levels - at all.Loss of coolant from the pipework going to LPG vaporisers is a prime suspect too.

The last one I got talked into doing was replaced with a Turner engine with top hat liners,a new radiator and most of the cooling hoses - the only way I could guarantee with some hope that the owner would get another 5 years out of the car.

[CBR]

...

Questions:

i) Can I use the LRL 0004 document in rebuilding my 55D engine?

ii) Is there a overhaul manual for the 55D engine? (I can't find one using Mr Google)

...

Hi Guys,

Just thought I would update this thread with some more information on the subject.

I have found the overhaul manual for the 55D engine! Where??? (and I feel like 'n plonker now) I found it in the car's Workshop manual (which I had all along, just didn't notice that all the info I require is actually in the Workshop manual). :blush:

Cheers

Chris