I have a 1990 ls 400 and it is squirting water from the right back of the engine. I can not see where it is coming from because it is blocked from my view. What water hose is it?

 

most likely it is a heater hose, but there are other things with coolant in them back there, IIRC... unfortunately, we would all be guessing as to the cause - one way to find out for sure - get it nice and warm while running and observe...

 

Is it water or coolant

 

being that it is squirting out, it must be coming from the coolant hoses, so its irrelevant whether it is water or coolant...

the only other thing in the area with water is condensate from the evaporator core when the a/c is on and in no way is it possible for it to squirt out... if it were to be plugged to the point where it doesn't drip freely, it won't build up pressure, instead it will soak the passenger floor board...