V8 disco problem

Ive got an x reg v8 disco, in the morning when you start it from cold it sounds like its only running on 7 cylinders and is very flat on acceleration, you can also hear water swishing about in the heater, after it warms up it runs perfectly, it doesn't overheat or use any water, anybody got any idea whats wrong . Thanks in advance.

I assume it is a 3.9, is it using any water at all, if so you may be well worth getting a pressure test done on the cooling system, it may be a leak or a porous or damaged liner in the block.

Its a 4 litre.

After leaving it overnight,without starting it up,remove the spark plugs,if one of them looks rusty around the electrode end or totally different to the rest this is the cylinder that is causing your problem.If it is cylinder 1,2,7or 8 then it you may just have a blown head gasket.If it is cyls 3,4,5 or 6 then its more likely a porus block.

Thanks, i'll check tomorrow.

Hi i've got a disco 3.9 lpg that seems to work the other way,starts great from cold but after a few mins on tickover misses badly on acceleration but runs ok on higher revs also noise from heater,no leaks though,any ideas,thanks,Mark