No the offroading did not cause this.
But remember that if you overheat the engine you WILL be buying a new one.
Rovers have a all aluminum engine, transmission and transfer case.
A all aluminum engine has steel cylinder liners, they have to do this because aluminum is stronger than steel but softer than steel so it will wear really fast.
You would be hard pressed to get 50,000 miles out of it if they did not do this.
But when you overheat the engine thjose liners will drop out of the cylinder and your engine is toast.
You need to find your leak, it wont just go away.

 

You will find that the Classic Disco I's are older and most problems have been worked out over the years.
The Disco II's was a BMW design and came on the market as BMW sold Land Rover to Ford in 1999 so there was high tect BMW electrical stuff and little support.

 

the thing didnt acctually over heat it was at the top of the "safe" when i turned it off. a leak in the intake gasket wouldnt make it over heat would it, lose fluid yes. i was thinking waterpump or thermostat.im gonna flush it and new thermostat soon as i get it in the mail. i have a receipt for the water pump at 118000 miles and have 140000 on the truck thats only 22000 on the pump seems low to me. its running smooth so i dont think there are any maror leaks like head gasket, but i will do all the minor things and work my way up to the major.

 

I've flushed the system and changed the thermostat. i know i will have to change the intake manifold gasket cause i had the same thing happen as before and its leaking out the front right and back left of the gasket. so can i do a test to see if the head gaskets are bad when i know the intake is, cause if its just the intake I'll do it myself. head gaskets are a different story with machining involved. the vehicle seems sluggish so I'm wondering if my timing is off causing it to overheat. or if coolent is leaking into the intake causing sluggishness, but then i don't what the overheating is attributed too. please help explain it to me. i just want to know what i'm up against so i dont have to open her up a bunch of times changing intake gaskets then finding i need head gaskets a week later.

 

The causes for overheating are a loose serp belt, bad water pump, clogged radiator, bad thermostat, low on coolant, bad radiator cap.
So start cheap and easy, check your belt for tightness and wear.
Then replace the thermostat, while the t-stat is out of the truck you might want to do a cooling system flush and replace youir radiator cap.
After your flush with the t-stat still removed and the upper hose off fill the radiator with water and then start the truck, how fast does the water come out of the engine?
If it comes out as fast as or faster than you can put it back in with the hose your water pump is good.
If your fan clutch is bad that too can cause overheating, when the engine starts to run hot does your fan come on? Not the electric fan but the clutch fan, it will be really loud when you rev the engine.

 

i replaced the belt and thermo and flushed already. the fan seems to be spinning fine, i read in the haynes manual that retarded timing can cause overheating and with the sluggishness of the truck i thought that could be possible. i just need to aquire a timing light to make sure its right, i turned it up a little and the truck seems a little more peppy but i don't want to over do it till i can get a light. my dad told me turn it up till it starts to ping then back it off a hair and thats usually pretty close.

does the fan spin loosely then kick in hard when its hot? i think I've heard it kick in.

 

Yes, the clutch fan spins free when cold and locks up to match engine speed when hot.
With a correctly working cooling system this fan should not come on unless you are really working the truck or you live in the desert and it is 130* in the shade.

 

so it won't come on till the top of the safe area on the gauge

 

Not sure when it will come on, mine never does even after 8 hours of off roading in August with the A/C on, and the temp gauge stays right at 9 o'clock.

 

i'm hopeing that advancing the timing helps mine, all the sympoms point to that, overheating, poor acceleration, and poor gas milage.