Manifold issue?

[TheSTRdude]

Looking for some help and part numbers here if anyone can help.

I have an issue with my starboard 7.4L where the risers/manifolds are reaching about 200 degrees on the port side bank. Other manifolds / risers are around 90-95 degrees. Engines are raw water cooled. Temp gauge is showing it's pretty normal, I caught it with an IR thermal temp gun. Considering the boat was once salt water - I'm assuming it's a riser / Manifold issue. Someone correct me if I'm wrong here.

So... going to have starboard manifolds / risers replaced along with both engines getting a new set of plugs, thermostats, and impellers.

My question -
What part numbers am I after?
-Manifolds / Risers
-Impellers
-thermostats

Looking at NuWave Marine for parts, it shows restricted, full flow, or block off gaskets. Which am I after?

Thanks in advance!

 

[Hoplite808]

I have a 96 7.4 LX MPI EFI Gen V motor and found cracks in both of my exhaust manifolds. The best deal I could find on the internet was to order them for in store pick up from West Marine. The part number was Sierra 18-1957-1.

https://www.westmarine.com/my-account/order/20385102

It sounds like the cooling water has stopped flowing through it for some reason. Before paying the $300 or more dollars for a new manifold I’d pull it off and check to see if there is simply a blockage that can be cleared first. Make sure cooling water is flowing through the hose going to the bottom of the manifold and then when you know for sure that’s working then pull the head and riser apart and take a look inside them for blockages. If it is salt crystals there are a bunch of ways to break them down and clear the channels. If rust has closed off the water jacket then it’s best to just replace them.

Also the full flow riser gasket is for the closed cooling system and the restricted one is for the raw water cooled system. The full restriction one would cause the same overheating problem you are describing in an open cooling system but would be used to keep coolant going out the exhaust in a closed system.