Have a TH magna and has developed a massive water leak. Appears to be in the valley running down the gearbox and comes out when motor is not even running. Tried to get the bottom inlet manifold off but seems something on the drivers side holding it back. Looks like to be a water pipe in the valley so is this the only way getting it out?

That pipe runs from the water pump to the back of the engine. You have to remove the water pump (and timing belt) to get it off. It is sealed by o-rings. The inlet manifold can stay in place.

It's uncommon, but in the second gen the pipe running from the water pump along the valley can corrode and start leaking if the coolant isn't kept up to specifications.

As above, the timing belt needs to come off so you can remove the pipe and water pump. Not a 5 minute job.

You can pull the pipe out without removing the cam belt or removing the water pump, but the corrosion, if any, will be where the pipe joins the water pump.

Thanks guys doesnt sound like an easy fix, damn

Changed the seal and water pipe, seal looked shot on water pump side but could only be a small leak which i had initially not the massive one i have now. How would the water pump have a massive leak

Could it be the water pump housing?

Changed the seal and water pipe, seal looked shot on water pump side but could only be a small leak which i had initially not the massive one i have now. How would the water pump have a massive leak

Yes, the seal looks shot on the water pump side because that is where the alloy has corroded the most. Two different metals there, the softer of the two corrodes the most.

Pretty much impossible to look at the seal and judge how much water flow would come from the leak once the system is under pressure.

You will need to pull the pump out and curse the person who hasn't kept the coolant in good condition.

Well took me 2 hours to get the damn water pump out, what a job and looks like its definite leaking out the back into the valley. Trying to source a water pump with housing is not an easy job as i dont want to use my old housing .

Good point, water pumps for the Magna don't normally come with the rear housing, which is the bit you want.
Tried Mits-fix?

Only found a couple off wrecked vehicles. There is a place in Moorabbin that sells them complete with housing for $172.
I bought one off ebay with housing but its the wrong one.