I am trying to remove the connection pipe between the thermostat housing and the water pump on a D15Z 2000. I removed the thermostat housing and disconnected the pipe from the water pump but I can't remove the pipe.
Do I have to remove the intake manifold? Please Help.

 

Always helps to include a photo or two if you have the means.

 

There's usually a lot of corrosion involved. Remove the pipe and thermostat housing from the car as a unit, then try to detach them. You may end up having to replace both.

 

Hopefully you have been able to get the connection pipe off. I have a D16 ('95) and the connection pipe gave me a little trouble as well when I rebuilt my engine. Some things to remember: The connection pipe goes between the water pump housing and the thermostat housing; hence the name. They are fit into each housing and sealed with an O-ring at each end. The problem you may be having with not being able to remove it may be due to the small metal tab built into the connection pipe. This table slides into a feature in the housing to prevent pushing the pipe too far into the thermostat housing. Combined with years of corrosion, your problem may lie here. Be sure to remove all hose connections from the connection pipe, there is 1 other (atleast on my D16).