Don't let the long list of faults put you off, these things will go wrong in any old car, and I probably shouldn't have listed them all. I'll write this review as a buyer’s guide, as no doubt that is what most people are looking for.
The 250 engine's bottom end is practically bulletproof. The bottom end is very strong and will usually take quite a bit before they break (any mechanic will agree).
The alloy head however is quite susceptible to corrosion, so make sure you use only genuine manufacturer FORD brand corrosion inhibitor in your cooling system. If a car is blowing smoke, it may also just be the valve stem seals, these tend to go easily.
One of the most common mechanical problems with the XF's, is that the secondary jet on the Weber carbie gets a bit blocked, and causes a flat spot on acceleration. To avoid this, just use a good fuel and occasionally a fuel additive to clean out your fuel system. The Weber carbies are usually quite good, however since Weber haven't made carburetors for over 15 years now the parts for them are fairly expensive. Otherwise the carbie is very reliable. The carbie model is the Weber ADM series.
Fuel injection systems are usually pretty reliable, just a bit more expensive if anything does go wrong.
Oil leaks commonly appear from one of three places, the rear seal, the rocker cover gasket, or the oil pressure switch. All are relatively easy to rectify. If oil is leaking from the front seal, that is a much bigger problem, as the engine has to be practically dismantled to get at it.
Both the automatic and manual transmissions for the XF's are quite strong and reliable, just keep up the general maintenance (and don't thrash the car too much!).
With the manual transmission, the gear lever will at some time pop out of the gear box; this is inevitable. Some lock tight can hold it back in place, or for the more meticulous, $50 Aust will buy a new fitting.
The XF is most prone to rust on the passenger side roof, just in the corner between the windshield and door frame. Also the corners of the boot lid on sedans is a common rust spot, as there are drains right there.
You might also want to poor some water through the plastic cowling along the windscreen, where the wiper motor is housed, this is another common rust spot, if the drain has been blocked with leaves or whatnot. You will know if it has rusted if the interior gets wet.
Otherwise the location of rust really depends on where the car has been, and what has been done to it. With any luck you can find one without rust.
Other common problems include things like door handles snapping off ($15 Aust will buy a new one)
The handbrake cable on these cars has a tendency to snap. If this happens, spend the extra to buy a new one so it never happens again (they are not expensive).
If the speedo does not work, it may just be the transducer at the gear box, or the little plastic cogs. If it is the actual speedo, have the price lowered. The speedo can cost 200 dollars to fix! Or you could get a new dash from the wreckers.
My two cents (though probably worth less) :
Despite what I have said, these are great cars! They are very reliable (mine has never broken down), and if something does go wrong, they are usually cheap and easy to fix.
Don't be fooled by the ignorant, the XF's are NOT performance beasts (but they have the potential). A standard 250 X-flow engine has adequate power for a car that size. They do have a bit more boot than most, and will squash any 4 cylinder, but don't think you will be beating any V8's, or new Commodores from the lights (I know it pains me to say it). The high torque at low revs does feel nice though! Handling is excellent, and the power steering makes things really easy. Lastly fuel economy on these is pretty average. Please note that this write up only refers to the 250 X-flow XF Falcons.
They are very comfortable cars. I love mine and am going to fully rebuild it in 8 months. I have probably missed something, but this will be a start for those of you looking to purchase an XF Falcon. If you want to ask more questions about the XF’s, or any Falcon, try the Australian forum on fordsix.com, my name there is ‘Silver Bullet S-pac’.
Sorry about being so long winded, but you did ask. If you got this far, thanks for reading.