1990 OMC 4.3L Exhaust Manifolds and Risers

[asdasc]

I have been reading a lot of the threads on here in an attempt to learn more about my boat and what I need to do with it. I have seen more than a few posters automatically reccommend replacing the exhaust manifolds and risers every 5-7 years.

Am I understanding that correctly? My boat is freshwater only, and granted I have had a few summers where there were only a couple hours put on the boat, but I still am running the original everything for the past 18 seasons. Am I overdue?

What would be the sign that they need to be replaced? What are the risks to keep driving it this way?

Help me learn! Thanks,

 

[Don S]

Re: 1990 OMC 4.3L Exhaust Manifolds and Risers

I have seen more than a few posters automatically reccommend replacing the exhaust manifolds and risers every 5-7 years.

When you read the archives, and things don't match up exactly with your boat or circumstances, then the advise is probably not relevent.

In salt water 5-7 years is early/normal.
Fresh water does a lot better.

Hard starting, hydrolock, could be an early indication of problems.

 

[asdasc]

Re: 1990 OMC 4.3L Exhaust Manifolds and Risers

OK, thanks. I feel a little better.

18 years sounds like a long time, but the boat looks new inside and out.

 

[bpmcl00]

Re: 1990 OMC 4.3L Exhaust Manifolds and Risers

if the boat had been out of the water for 5+ years wil lthat have helped the life of the risers and manifolds?

 

[Gary H NC]

Re: 1990 OMC 4.3L Exhaust Manifolds and Risers

if the boat had been out of the water for 5+ years wil lthat have helped the life of the risers and manifolds?

It could...If they were drained and it was a freshwater boat.
Rust never stops but if they were dry for 5 years it slowed way down..

 

[Bondo]

Re: 1990 OMC 4.3L Exhaust Manifolds and Risers

Fresh water does a lot better.

Ayuh,....

Up here on the Sweetwater Seas,.... 30/ 40 Years is not unheard of.....

Matter of fact,....
Freezing,+ Splitting is what does in 99% of the replaced exhaust manifolds....
Rusting thru is pretty much a Non-Issue.....