I looked in the engine bay of the formula I just bought when I was putting in a battery and I noticed a kind of screw plug on tge top of the water pump. On my 86gt a coolant line goes here. Is the cooling line routing different on the 88s? Why does it have a plug in that hole?

The heater core return was plumbed to the water pump on 85 - 86, they redesigned the passenger side coolant pipe for 87 - 88, the heater core return is near the right front cradle mount.

So you're saying tge port in the top of the water pump is supposed to have a plug in it?

quote Originally posted by RilesOfSmiles: So you're saying tge port in the top of the water pump is supposed to have a plug in it?

That is correct.
If you ever buy a replacement pump, it may have the hose fitting there, and you'll need to take the plug out of your old 88 pump and put it in the new pump. The pumps are the same and can be interchanged if you block off the unneeded host fitting.

quote Originally posted by Formula88: That is correct. If you ever buy a replacement pump, it may have the hose fitting there, and you'll need to take the plug out of your old 88 pump and put it in the new pump. The pumps are the same and can be interchanged if you block off the unneeded host fitting.

Usually the pump comes with the plug installed. When installing on an 85-86, you must transfer the fitting for the heater core return hose.