On Christmas Eve 2007, my V8 slipped a cylinder liner on cylinder number 5.
I'm not sure how the cylinder number scheme goes, but I would imagine that cylinder 5 is on one back and (your) cylinder 6 is on the other bank, but in the same V, if you know what I mean.
My engine, which had 190,000 kms on it, suffered a cylinder liner slip, and for a couple of weeks prior to the failure, I've noticed sloshing sounds inside the cabin, as if there was air trapped in the HVAC heater core.
Since my block had to be replaced, I bit the bullet and ordered a tophat sleeved block and fitted a 4.6 crankshaft and camshaft. So I now have a fully rebuilt 4.6 V8, plus new water pump, thermostat and radiator. I even fitted new O2 sensors, just to be sure.
It's cost me AUD$8400 all up, so I hope my Disco will last at least another 200,000 kms. Its been a very expensive Christmas for me.
Sorry to hear about your woes, but it really doesn't sound too good. BTW, I did not have a scanner so I can't tell you if my cylinder number 5 ever reported a misfire. And Aussie spec Discovery II do not have a "check engine light", as far as I know.
Why don't you do something simple like pull out the spark plugs and check the condition? If cylinder number 6 has a much cleaner spark plug than the others, then there's some coolant leak into the combustion chamber, and the moisture is steam cleaning your plug tip.
Hopefully when you pull the spark plugs out, they ALL look the same. Then it's a case of tracking down the leak. Perhaps its the troublesome little hoses that connect to the throttle body, underneath the butterfly. These tend to leak badly and you'll see a build up of crusty dried coolant. The fix is a kit which is available from LR spares.
Maybe it's that simple. I hope so for your sake.
Lawrance Lee
Melbourne, Australia
Good luck with your search.
