1990 200 TDI numerous symptoms, finding out on Sunday but what does anyone think?

Hello all,
I have got a thread currently running about this particular Landy called 'Head Gasket gone on Defender 200 Tdi-Please help?' but i dont think it is appropriate anymore (as it may not be the hg) so i have started this thread, i hope this is ok with everyone! I would love to hear what anyone thinks the cause is of the symptoms below, it is going to the local 'Landy expert' on Sunday so we will hopefully find out what the problem/s is but i am intrigued as to what anyone suggest it may be)
Ok, here goes:
These are the facts:

* My Dad's Land Rover has developed problems starting that has gradually got worse
* There is a lot of smoke when it eventually starts, it continues to smoke when ticking over and running at a leisurely pace but gets worse when under strain (going up hills or revving)
* The 200 gets from 'A' to 'B' ok ok on the flat but struggles very much up hills
* My Dad claims that the exhaust fumes have become very very hot, seemingly, so much so that they could burn.
* There is no 'phut phut' sound near the engine, i have been told that this sound could indicate the hg has gone
* My Dad's friend has replaced the lift pump but the engine runs no differently
* One of the 'leak off' washers from Injector number 1 was leaking so i have bought replacement ones and the bolts that go with them, i have been advised that i should be careful not to overtighten these?
* It has done 175,000 miles, a friend suggested the tappets could be worn?
* It has recently had a replacement air, fuel and oil filter and replacement oil
* A friend suggested the cam belt (replaced 30,000 miles ago) may have slipped, thus putting the timing out, is this a possibility? (i was under the impression that cam belts usually break, not slip)
* The temp gauge rises to midway (My dad described it as '12 o'clock) after 3 miles but stays there for a 50 miles trip (it always used to 'rest' at below 'midway', or '10 o'clock')
* My Dad had to put a 'watering can' full of water in the system 2 weeks ago

I look forward to your thoughts on this.....

when did it last have a proper FULL service ?

Ermmm...im afraid i didn't know there was more to a service than replacing the fuel, air and oil filters and oil. The Cam belt was changed 30,000 miles ago. Please explain to a fool what else there is to a full service? Sorry for my naiveity.

Ps- My Dad is driving the 200 to the local Landy 'expert' tomorrow which is 20 mile away, is he risking it a little being as it could possibly be the cam belt that has slipped?

check clearances and IP for previous tampering would be a good start, flush out the rad and heater matrix, sort the leak offs and fill the fuel filter with a bottle of injector cleaner would be a good start

Thanks for that good advice, can i please ask what you mean by 'IP'?

injection pump, there's quite a few good guides around which will help you get it close to the correct setting - but do the tappets and rad flush first

The timing belt CAN slip or someone could have put it on either advanced a notch or retarded a notch - neither is good. Advanced means it will run hot and noisier and use water. Drive it up to beside another 200tdi and have a wee listen to both.
Sean is right about the pump - check for tampering - you can ratchet those Bosch pumps up to high power by opening up the vacuum pump and messing with some screw settings - look for tampering on a plastic black disc set into a disc shape metal area on the pump. Knocking the power up means really hot exhaust and more noise.
It's a ballix not knowing what is wrong immediately but take your time and eliminate each possibility. Is there anyone lives near you on this forum could take a look?