exhaust manifolds / risers

[Wahoo Cruiser]

We have a leak at the riser gasket on our 1983 5000 sunexpress 228 motor, But I have a few questions,
How often do exhaust manifolds need to be changed(these are OE)?
Should we change them out ho matter what?
External inspection stud and hardware rusted as usual, I want to remove risers and inspect manifolds visually first before changing parts.
Should we just change riser gaskets and stud hardware?
What should we look for inside?
Can manifolds be sand blasted internally? I was told yes...

Compression test is strong in all cylinders, 1 is slightly lower as usual. Engine temp runs 150-160 @ times when run hard gets to 180 temporarilycomes right down. No water in oil

 

[Don S]

Re: exhaust manifolds / risers

When you remove the riser, make sure the areas in red in the pic below are metal and not black carbon. If it's not metal any more, replace the manifolds and risers.
IF they are plugged up with rust, replace them, DO NOT clean them. The rust comes from inside the manifolds and indicates they are failing. again, replace them.
Saltwater boats get manifolds replaced about every 8 to 10 years.

You may not have center rise manifolds on your engine, but the gasket surface and procedure is the same.

 

[sparky71]

Re: exhaust manifolds / risers

Something to add; If the surfaces don s spoke about are ok where can we get the risers for thes older style(risers at rear of manifolds) manifolds?
All of the ones I see are for center rise. Are they the same?

 

[achris]

Re: exhaust manifolds / risers

Something to add; If the surfaces don s spoke about are ok where can we get the risers for thes older style(risers at rear of manifolds) manifolds?
All of the ones I see are for center rise. Are they the same?

Still available from Merc (part# -76351A04) ...Not the same as centre rise
Try www.mercruiserparts.com

Chris..............

 

[sparky71]

Re: exhaust manifolds / risers

Thanks chris that looks identical to mine.What is the difference between 3" and 4", is it the diameter of the outlet before it goes down into the "y"?

 

[achris]

Re: exhaust manifolds / risers

Thanks chris that looks identical to mine.What is the difference between 3" and 4", is it the diameter of the outlet before it goes down into the "y"?

Yes....

3" and 4" is only relevant to the centre riser elbows....

Chris..........

 

[Don S]

Re: exhaust manifolds / risers

Sparky, if you have questions, start a new thread of your own, let's not hijack WC's thread and turn it into yours.

 

[sparky71]

Re: exhaust manifolds / risers

Sorry for the confusion Don, but this is actually my boat the OP is talking about. We went halfs on it,and are going to be doing this together.Just trying to add to his question to get as much info as we can.Again sorry for the confusion.
Dan

 

[smithrock]

Re: exhaust manifolds / risers

When you remove the riser, make sure the areas in red in the pic below are metal and not black carbon. If it's not metal any more, replace the manifolds and risers.
IF they are plugged up with rust, replace them, DO NOT clean them. The rust comes from inside the manifolds and indicates they are failing. again, replace them.
Saltwater boats get manifolds replaced about every 8 to 10 years.

You may not have center rise manifolds on your engine, but the gasket surface and procedure is the same.

Don, in the pic, which ones are the water inlets and which are exhaust outlets?

 

[bolo78910]

Re: exhaust manifolds / risers

the area mark with red are the water passages, the big hole in the middle is for the exhaust only.

 

[smithrock]

Re: exhaust manifolds / risers

Okay, so could a gasket leak from the water passages into the exhaust port cause water to enter the engine and oil? I have water coming out my #1 cylinder.

 

[achris]

Re: exhaust manifolds / risers

Okay, so could a gasket leak from the water passages into the exhaust port cause water to enter the engine and oil? I have water coming out my #1 cylinder.

Did you read the rest of this thread? Don't hi-jack other people's threads!... Start your own ....

 

[smithrock]

Re: exhaust manifolds / risers

Sorry! I do have one regarding my problem! I saw the pic that Don posted and it related to my problem so I thought i would ask. Just trying to solve my problem, didn't intend to hi-jack anothers' thread!