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Rebuilding 4.0 V8 Head


Big Landy Fan
Hi all

Due to A house Sale falling though I am feced with the propsed of replacing a head Gasget in a pub car park ... advice apprecated

The car is a Disco 11, V8 with the later top end (THOR?) what manual would be best for this?

the Car has coverd 80+ miles and has a tick while fully stamped i dont beleve that this car has been well serviced, I am thining it would be a good idea to replaced cam shafts and tappets while i have it all apart - comments aprecated Good/Bad. do this as well while you are there

Parts where to source these from not nessarily the cheepest but a good balance of cost/quality I will be putting about 100k miles on this before i will get rid ...

Its on Gas, not everyones ideal but it makes it afordable for me, its a BRC system any ideas where i can get a manual on how to disconect it?

I have thought about getting someone to do this for me even at a cost but alot of people wont touch the gas system and just dont want anything to do with the engine ... even if it was not there even independants around here are not very helpfull. Plus I want to do it

I am aware that there could be issues with the block ... but i think rebuling the heads at this millage would be prudent anyway. comments on this approach

any constructive advise apprecated!

Having done this job on a driveway it is not all that bad!

The chamber is just a case of taking off the various pipes and attachments (speedo cable, air intake and a few other IIRC) then 8 10mm bolts. Make sure you make a not of where these olts are from as they are different lenths.

When you take it off be careful that the location lugs on are in place (one of mine fell thur and spent a day finiding it!)

If your LPG kit is anything like mine then you will have 8 rubber hoses to take off now, nothing too dramtic. The system may release a small amount of gas but i doubt it, it should be sealed by the regulator.

From there it is just a case of unbolting the Air con pump (if you have one) Alternator, Vicious fan assemble (bit 32mm?? nut, tho a hammer and chisel will do it at a push) and then the inlet mainifold and exhaust manifolds and rocker covers.

Once you get to this stage the fun kinda begins. The head bolts need to come out but make sure you realese them slowly and in the right order (reverse of tightening) this should stop the head warping. You will need a new set of bolts to be on the safe side (I STRONGLY reccomend you get new bolts - Don't ask)

Thing to look out for - if i did it again I would drain the coolant before taking the heads off, otherwise if it does drain it spills into the bores.

At this point I would also send the heads to be checked to see if they are warped at all. Worth it at ths stage rather than putting it all back togther and blowing a gasket again in a few tho miles.

Refit is the reverse!

It is just like any onlder engine when you get past the ancillaries.!
Thanks Ben

a few more questions, did you do the cams and tappets at the same time?

Did you repaint the covers?

Where did you get the head chequed - how long did it take to come back?

witch manual did you use?

the car has air con taking the pump of i assume the gas escapes do i have to get someone to do this for me or it it ok to do youslef?

How long did it take?

once again thanks

Having done those jobs, thats an awful lot of work to do in a pub car park.

I would be more inclined to lay up the Disco until you have somewhere less public to work and buy/borrow a cheap runabout in the meantime.

Otherwise somone always nicks your tools when you go for tea/pee.
I completely hear what you say and i have delayed this hoping to move to beter facilites ... but it needs doing

I cant afford to lay the car up nor do i have anywere to do so otherwise i would carry out the work there

I am even concidering doing this in a frends drive but thats 30 miles from where i live

I am trying to get as much information as possible at this time so i am prepared


I have got quotes from Rimmer Bros and a request to RPI for parts any where else people recomend

Anyone got any more advice

Quotes now coming in

the gasget set, there is significat price diferance between Genuine part and non I am tempted to go for the genuine part becuse I want the best quaity HG and i dont want to have to do this again in the neer future but I also dont want to be ripped of just because it says LR on the side of the box ... any advise on this one

Hi Aidan,

I used a Paddocks gasket set for my Range Rover 3.5 when I had to do the head gaskets (I used composite) and it was absolutely fine. Rimmer Bros I thought were extortionate for what is essentially the same stuff as others.

It is quite a lot of work to do in a car park, but I was forced to do mine in mate's driveway in the snow, and it was my first time, so it can be done!

I had the heads machined and checked and they were back within a week.

For length of job I stripped all over one weekend and dropped heads in Monday morning before work, had the heads back Friday and re-assembled over that weekend. I didn't replace cam or tappets at the time due to cost and time constraints, but definitely would have if I'd had the cash. All is exposed so if you have the money then it makes good sense.

As for air con, not sure of your age of car, but mine was an 89 3.5EFi and the air con pump removal didn't let any gas escape.

Manual for yours, I've no idea, sorry matey.

Hope this helps a bit,


Many thanks for a very helpfull post and the encoragment !

mine is a 99 ... so later head and no Hayens or similar manuals, going to get a workshop one of ebay i think

I am considering doing timing chain and rockers as some of the webishgts talk about it but i dont know if thats just looking for more part sales

The timing chain doesn't have an adjuster and goes slack. That retards the valve and ignition timing ( on a distributor model).

You need the chain and both sprockets, check the cam lobes, especially the ones under the block reinforcings, they get short of oil and round off.
The Hydraulic tappets hollow out on the bottoms.

The rocker arms wear on the tip where they contact the valves and slightly wear in the pivot, the rocker shafts wear underneath, so look closely, the tops look OK.

Hi Aidan,

I would definitely do timing chain and sprockets as Templar says. I would also (if funds allow) do tappets and cam as when I eventually took mine apart the tappets were very dished on the bottom and the cam quite rounded.

Let me know how it goes, best of luck mate,

Chris, Hugo

Thanks for the in put, I will put the timing gear on the To Buy list

I will look at the rockers when its all apart

I cams and Tappets are the most likley for a rev related Tick that i have at the moment

Hugo i have been reading the websight "teflon" you put up on the other tread great read

I will be keeping everyone iformed of my process looking to stip it all down in a fortnight when most of the parts should be here

I just hope its not a sliped linner or its all out again (and i will have to hire some where to do that!)

If it came to that i would probalby put a 4.6 short block in (with top hat linners) so have to do cams and everything else again!

what do people think about the oil pump? again some people recomend its replacement

If you do the cam and put new crank bearings in, put an oil pump on.

Pack it with Vaseline or it won't prime up.

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