freelander problems

ok everyone here is my problems.
 
i have an 02 freelander se 2.5 v6 no warranty.
the check engine light is on and the main code that autozone was able to read was p0171
and the coolant was disappearing. i noticed the coolant was disappearing after overheating
on my way to a relatives house about 30 miles from mine. it did not run hot long. i let it cool
and added coolant to it and it was fine. About 2 weeks later while we were driving it again it
overheated again and did the same as previously stated. so i took it to a mechanic and he has
told me that the engine code was one of about 5 all of which pointed to a vacuum leak. and
the coolant was from a leaking water pump. so the mechanic did further searching on the codes
and has told me that it is a blown head gasket. and that i have a slight knock. now my problem is
that after the check engine light came on i changed the oil in it and the oil was NOT milky at all. I
also have never seen any indication of anything leaking form the car. I do know about the head gasket
issues with the freelander. Now what is the likely hood that the head gasket is indeed blown but the
coolant is not mixing with the oil. the mechanic is recommending replacing the whole motor.
now should i do this or could the head be fine and just needs a new gasket?

every week i seem to read and hear about this problem
with the 2.5 kv6 motor (used first in the rover cars in england)
i see you say that there is no oil in the coolant but, is there a oily film in the coolant
overflow tank? replacing the headgaskets will not work with this motor due to
the cylinder liners moving when the engine overheats and dropping slightly.
the coolant leak is prob coming from the thermostat housing under the intake
manifolds and leaking out the drain hole next to the water pump.
sorry...

I agree fully. There is also another systematic coolant leak from the Heater Core. If you remove the skid plate (the cover under the engine) you can see if your Heater Core is leaking. It's a metallic shiny corrugated squarish metal can located directly in front of the engine. Orange stains and hardened orange droplets are shure signs of a leaky heater core. On my 2002 Freelander the Thermostat Module has been replaced 3x under warrany and now in it's 6th year, started leaking again 2 month's ago. Chaging the thermostat is not a simple job. Bad car, bad service and horrible quality.

Hi, im new on this forum, but have my freelander''00 1.8 for 6 months. Replaced: engine, water pump, timing belt, all pipes, thermostat.
i have the same problem with coolant dissapearing- pipes 100% brand new, not leaking at all, nothing under car in mornings, or so, NO coolant in oil, NO oil in coolant expansion tank, NO oily films in there aswell,  coolant KEEPS  dissapearing...  toping up about 0.5- 1 litre  a day depends on drive. Just passed National Car Test, CO emissions are perfect, car is perfect, just coolant pisses me off... Any sugestions?
Regards-Ray