Rust in manifold

[acdc96]

I needed a new exhaust manifold riser gasket for the port manifold on my 1987 Mercruiser. I cleaned and painted the riser and it look great. I looked down into the manifold and it had rust chips in it. Big chunks. The manifolds drain water perfectly and don't overheat. How can I remove the rust without removing the manifold?

 

[Scott Danforth]

you cant.

I believe its time for new manifolds and risers

 

[alldodge]

I needed a new exhaust manifold riser gasket for the port manifold on my 1987 Mercruiser. I cleaned and painted the riser and it look great. I looked down into the manifold and it had rust chips in it. Big chunks. The manifolds drain water perfectly and don't overheat. How can I remove the rust without removing the manifold?

There may be a way, but are you willing to take the chance that something could come loose and get caught in a place you wouldn't want it to go? Another thought, if your running in salt water you may want to think about replacing them if they have some years on them. How old are they and are you in salt?

 

[Glaspar_Fan]

Did you try a vacuum?

 

[Bondo]

I needed a new exhaust manifold riser gasket for the port manifold on my 1987 Mercruiser. I cleaned and painted the riser and it look great. I looked down into the manifold and it had rust chips in it. Big chunks. The manifolds drain water perfectly and don't overheat. How can I remove the rust without removing the manifold?

Ayuh,...... Ya can't,.... Ain't gonna happen,..........

 

[acdc96]

The manifolds have been on the boat since I bought it in 2003 or 2004. It is a brackish/saltwater boat. The previous owner had it repowered in 2000 or 2001. The manifolds were flushed every year with freshwater. I managed to get most of the chunks out buy chrushing them with a flathead and a combo of vacuuming it with a air mattress filler nozzle and flushing it with water. The boat hasn't been in the water since 2006. I pressure checked them and they don't leak.

 

[90stingray]

But if they are "chunking" apart from corrosion, they are on their way to failing. Then you will be repowering as well as buying new manifolds. You have been warned... Good luck!