What is purpose of the block-off plate between manifold/riser on VP 3.0L?

[happycamper]

Can anyone tell me the purpose of the metal plate (block-off plate?) that's sandwiched between the two silver gaskets between the manifold & riser on a '97 V/P 3.0L?

Is the orientation of this plate important? I have the OEM service manuals, but the drawing detail isn't adequate to show the orientation.

 

[Chris1956]

Re: What is purpose of the block-off plate between manifold/riser on VP 3.0L?

Happy, The block off plate is normally used to seperate the raw water cooled part of the motor from the fresh water cooled part of the motor. I assume you motor has fresh water cooling? In this case the risers are raw water cooled. You likely need gaskets on each side.

 

[happycamper]

Re: What is purpose of the block-off plate between manifold/riser on VP 3.0L?

Chris,
Thanks for the reply.

My engine is raw water cooled. So, I'm still confused about the purpose; do I even need this plate?

 

[Chris1956]

Re: What is purpose of the block-off plate between manifold/riser on VP 3.0L?

You might look on the web for an exploded drawing of your motor, and see if the plate is original. For example, MerCruiser has several different kinds of riser gaskets which allow more or less water to pass between the manifold and the riser. They choose the correct gasket based upon engine type and cooling type. Maybe your motor is supposed to have the blockoff plate, for some reason.

 

[happycamper]

Re: What is purpose of the block-off plate between manifold/riser on VP 3.0L?

I have looked at exploded views, which do show this plate sandwiched between the two gaskets. Unfortunately, none of the drawings are clear enough to show the orientation of the plate.

My concern is that it may be installed wrong, which might explain why I blow the circulating hose every other year.