When to replace manifolds and risers

[Irie308]

Nah! Just as long as you run it before launching to check for leaks.
But personally, I wouldn’t waste my time just doing risers. If you’re going to jump in there then you’re better off getting the whole kit with manifolds, risers, gaskets, bolts, etc., and starting fresh. Once you take the risers off the manifolds are easy. It’ll be a good time for you to take a close look at the hoses while you have it apart. Maybe your PS cooler and anything else in the raw water line too. I see your 320 is an 05. If you boat in salt or brackish water, aren’t the original owner, or don’t know for sure when these things were done, going through it all might be a good idea and save you some headaches down the road.
While I’m not a marine mechanic, I am a pretty competent do it yourselfer (at least with the gassers, diesels are a whole new world for me) and have done a bunch of work on my stuff and friends stuff over the years and other than failure due to raw water intrusion, not much else sends marine motors to early graves so IMHO it pays to stay on top of that stuff.
The 4cyl, 6cyl, and big block kits are pricey for what they are, but the small block OEM kits are a relative bargain and readily available from a lot of different places at competitive (maybe $600 or less) prices.

Interesting, I was going to closely inspect the manifolds while i had the risers off however i thought this was a non issue for the closed cooling systems where the raw water doesn't come in contact with the manifolds?

 

[scoflaw]

If just replacing the risers do you need to run the engine afterwards? Reason i ask is i'm planning to do this over the winter once the boat has been winterized. So if i replace the risers the engines wouldn't be fired up until the spring.

Interesting, I was going to closely inspect the manifolds while i had the risers off however i thought this was a non issue for the closed cooling systems where the raw water doesn't come in contact with the manifolds?

You hijacked the thread, and nobody has any idea what your working on.. so, yes, if your manifolds are in the closed loop, they are fine.

 

[Irie308]

Sorry, didn't mean to but thought my initial question may be relevant to the OP project.

 

[JVM225]

Interesting, I was going to closely inspect the manifolds while i had the risers off however i thought this was a non issue for the closed cooling systems where the raw water doesn't come in contact with the manifolds?

Didn’t realize you have a closed system.

 

[CAVEMAN930]

I removed the manifolds and risers from my 93 400EC in March. This boat spent it's entire life on the Great Lakes and the manifold/risers were original. After removing them they were in excellent condition.

Salt water is what destroys metal. Saltwater boating is brutal.

 

[CaptRonn]

Salt water is what destroys metal. Saltwater boating is brutal.

Gee......really? What a revelation! Thanks for sharing!