V8 4.6

smurphy · Oct 18, 2009

Im thinking of trading up to a Range rover 4.6HSE now i know all about the bad bits on the car. I have at the moment a 95 V8 Disco on LPG which now runs sweet as a nut. I'm just wondering if the 4.6 has a crap block or was it just the 4.2? thanks Steve

gavbriggs · Oct 18, 2009

the 4 and 4.6 are crap blocks, try and get a top hat linered one if you can, ive been through the mill with my 4 litre. had to have a t/h block!

rustyrangie · Oct 18, 2009

i'd keep the disco, you'll be kicking yourself when that fancy electrickery starts letting you down

oh and the engine, not as good off road etc

i thought the 3.9 and 4.0 were the same block? 4.2 is same as 3.9 just longer stroke crank.
i agree with the th's tho if and when my engine goes wonky i'll be getting a top hatted one, prob a 4.6

smurphy · Oct 19, 2009

What do you mean by getting a tophat one?
Do you mean get one that has been redone with tophat liners or did they redo the engine on later models with the block done?

norseman · Oct 19, 2009

All 94mm bore V8's have a weakness for cracking blocks behind the liners, hence liner movement & the 4.6 appears to be the most prolific. The 4.2's problem(?) stems from the fact that LR extended the stroke in standard form & thereby introduced additional reciprocal forces/stress on the bottom end. Bearing in mind the LSE was essentially a 'mule' (except that the makers got buyers to do their testing for them, nice one LR!) for the forthcoming P38, those later engines (4.0/4.6) had stronger bottom ends. I'm not an engineer but although I follow how a 'top-hat' liner cannot move, I fail to see how the design can solve the block problem.

eightinavee · Oct 19, 2009

norseman said:
All 94mm bore V8's have a weakness for cracking blocks behind the liners, hence liner movement & the 4.6 appears to be the most prolific. The 4.2's problem(?) stems from the fact that LR extended the stroke in standard form & thereby introduced additional reciprocal forces/stress on the bottom end. Bearing in mind the LSE was essentially a 'mule' (except that the makers got buyers to do their testing for them, nice one LR!) for the forthcoming P38, those later engines (4.0/4.6) had stronger bottom ends. I'm not an engineer but although I follow how a 'top-hat' liner cannot move, I fail to see how the design can solve the block problem.

Simples,the wide flange of the top hat liner gives the head gasket something to seal against,so if any coolant makes its way up the back of the liner it cant get past the flange or head gasket.
Turner engineering go one better and fit an O ring at the bottom of the block to stop the slight possibility of coolant making its way down into the sump.(They are the only ones to offer a 3 year warranty on their TH blocks.)
The flange also ensures that the liner cannot move up and down as it did with the original design when the block material failed to give enough interference fit to grip the liner.
Shame Rover didnt do it in the first place.(And put a larger,rather than smaller oil pan on it.) The vehicles could then have retained more value and gone properly into old age.

gavbriggs · Oct 19, 2009

eightinavee said:
Simples,the wide flange of the top hat liner gives the head gasket something to seal against,so if any coolant makes its way up the back of the liner it cant get past the flange or head gasket.
Turner engineering go one better and fit an O ring at the bottom of the block to stop the slight possibility of coolant making its way down into the sump.(They are the only ones to offer a 3 year warranty on their TH blocks.)
The flange also ensures that the liner cannot move up and down as it did with the original design when the block material failed to give enough interference fit to grip the liner.
Shame Rover didnt do it in the first place.(And put a larger,rather than smaller oil pan on it.) The vehicles could then have retained more value and gone properly into old age.

to add to that, the pressures from the coolant system are very low compared to the pressures of combustion. keeing the combustion chamber sealed means the coolant system can't get over pressurised from combustion and spit water out! this is what seems to be the most common sign/symptom of liner slip.

i would imagine if water was passing into the oil behind the liners stuff like k-seal/ceramic addative etc would be sufficient to seal it.

rustyrangie · Oct 20, 2009

i'm no expert on the v8's yet, although i'm sure a problem sooner or later will see to that

but i'm not convinced an o ring at the bottom of the liner will make a big difference, after all the 'k' series rover engines had one and we all know how crap they are

i guess there's no sure answer to an altra relialbe v8 a lot of it comes down to luck on how good your casting is.

norseman · Oct 20, 2009

Thank 'eight / gav' I've always wondered, now I know! Still think I'll stick to the 3.5 though.

eightinavee · Oct 21, 2009

rustyrangie said:
i'm no expert on the v8's yet, although i'm sure a problem sooner or later will see to that but i'm not convinced an o ring at the bottom of the liner will make a big difference, after all the 'k' series rover engines had one and we all know how crap they are i guess there's no sure answer to an altra relialbe v8 a lot of it comes down to luck on how good your casting is.

I think the lower O ring is just a bit of extra insurance - talk to Richard Turner and you will quickly realise how he will go to great lengths to build a reliable unit.
Funny thing is the K series is now becoming a reliable,cheap long term prospect - built properly,with all the mods done they are doing well, and not scrapping as many cars as porus blocked RR's and Disco's.(Unlike TD5's which get VERY expensive to repair.)

eightinavee · Oct 21, 2009

Forgot to say - sticking with the 3.5 is the easy,simple long term choice.Well set up it can be a smoother,more pleasant engine than any of the bigger ones.Esp with EFI and more modern ignition systems.

V8 4.6

smurphy

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gavbriggs

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rustyrangie

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smurphy

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norseman

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eightinavee

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gavbriggs

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rustyrangie

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