2000 Rover 25 Drove through water...

Ok so have you tried to turn the engine over manually with the spark plugs out and in nuetral?

Yes.. Still made the same single click!

Ok so you can turn it over manually with a wrench? If so then pull the starter and take it to your local parts store and have them test it.

You can only crank/turn it so far then it refuses to turn anymore.. the starter works fine as have removed it and tested it. Am thinking now that perhaps it is piston related?.

So have you removed all the spark plugs and then tried to crank it over to see what it does?

All spark plugs removed.. When you try to manually crank, will only crank quater.. Maybe halfway, then stops! Also, piston's are 3 up 1 down.. The manual states should be 2up 2 down.. Air filter was sodden so am guessing water has been taken into engine..

All electrics work fine as does starter motor/ battery/ fuel pump..

Ok so tell me how much oil is in it? When you went through the water did it die from takiing water into the engine? The two up and two down is at TDC on number 1 cyl. Also what RPM was it at when it died?

It has plenty of oil in..almost full. I was going around 10/15 mph when I drove into the water.The car just stopped dead..So im guessing that when the exhaust got under the water..the engine took in water at that point killing the engine?

No that wouldn't have killed it other wise I could have killed my truck everytime I dock my boat. It took water into the intake that is why the air filter was wet. How wet was the air filter? What I am thinking is the water got into the engine and hydro locked it and maybe bent a rod or something. So what you do now it bring the timing up to tdc and check the cams are they aligned (see pic) and check the pistons to make sure they are as they should be.