Welcome to OOF
I'd love to go to Japan!
But I think I'd rather go when the place isn't over run with drunken Brits, Aussies, Kiwis and Saffers!
Certainly the misfire at cold start with coolant loss is indicitive of water getting in the cylinder/sSurely that would lead to excessive pressure in coolant system, seeing as cylinder pressure are way more than coolant pressure.
it's showing exactly the same symptoms mine did.
Whenever I solved the external leaks(cap, expansion tank and top hose) the leak got worse.
I was resigned to changing the head gaskets, and got the parts together. By the time I started the job, more steam than normal was visible in the exhaust gases as it warmed up. But it wasn't pressurising the cooling system as much as blown head gaskets I had seen previously.
Removing the O/S head revealed a rotten gasket that was the cause of the leak, and a nicely steam cleaned piston. The other side was in a similar state, but wasn't showing signs of leaking.
If it isn't leaking externally(which can take some time to prove) then it has to be internal.
It’s a 2011 facelift XF 3.0. V6 diesel portfolio beautiful car.Methinks his fuel computer is telling porkies, as no way will he get that sort of MPG unless driving everywhere at 50mpg.
My XJ - same engine, same weight - averages 32.5mpg over several tankfuls. Manually calculated, as the fuel computer is worse than a cheap watch.
But the wrong gearbox.....the 8 speed makes a massive MPG improvement (as it has the extra 2 cogs plus the ZF8 also locks the torque converter in every gear).
I'm going to throw another one into the mix, as per my old blue prefacelift....weeping core plug.
From memory what you have is not far from what I experienced.
How was it diagnosed/tracked down?
was the water pump leaking when you took it to serek ? or the rad ? or what ?
back then you had a visible leak which I assume was resolved and the minor coolant loss is proving hard for you to find ?
Sounds like you need to pressurise the cooling system cold and see where it leaks.
I wouldn't be worrying about the head gasket until you've completely eliminated the radiator (passenger side tank seems to be most common area), radiator drain valve, HBV, water pump, oil cooler cover plate, heater matrix and all the rubber hoses for starters.
I also fail to see how you can have enough water leaking into a cylinder to get a misfire yet it's not immediately blowing the pressure cap under load. Sure you haven't got a leaky scuttle dripping water into the plug wells?
He loves his car and when I told him his mpg was being questioned this was his response ......
My E92 330d would average mid 30's around town but could easily achieve 48mpg on a run. Figures are real world miles travelled from empty to full to empty again. That thing would go from my house to a place we stay in Cornwall and back on a tank, a round trip of over 526 miles, and I don't hang about. I loved that car, it had a cracking engine.
