Exhaust manifolds... Aluminum vs regular?

acdc96

Chief Petty Officer
Joined
Apr 23, 2013
Messages
412
The exhaust manifolds on my boat are in need of replacement. The risers are in great shape with very little rust in them so I won't replace them at the moment. I can buy regular Mercruiser exhaust manifolds with the hardware and gaskets for under $200 each side. I was looking online at some aluminum exhaust manifolds for sh!ts and giggles expecting them to be $1000's of dollars but they were reasonably priced. About $250 without shipping per side. So probably $300 per side total. I'm tired of replacing worn out rusted parts on my boat. Would spending more money on the aluminum manifolds be better for the long run or do they need regular replacement like the cast iron ones? Here's a link for the aluminum manifold in looking at: http://www.michiganmotorz.com/mercr...s8b4Gr9uArrkF0Gvk9pEQsbyUXalYrAv4QBoC4Nbw_wcB
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,583
The exhaust manifolds on my boat are in need of replacement. The risers are in great shape with very little rust in them so I won't replace them at the moment. I can buy regular Mercruiser exhaust manifolds with the hardware and gaskets for under $200 each side. I was looking online at some aluminum exhaust manifolds for sh!ts and giggles expecting them to be $1000's of dollars but they were reasonably priced. About $250 without shipping per side. So probably $300 per side total. I'm tired of replacing worn out rusted parts on my boat. Would spending more money on the aluminum manifolds be better for the long run or do they need regular replacement like the cast iron ones? Here's a link for the aluminum manifold in looking at: http://www.michiganmotorz.com/mercr...s8b4Gr9uArrkF0Gvk9pEQsbyUXalYrAv4QBoC4Nbw_wcB

Iron
Will work for fresh and slat water, last 7-10 years in salt water, can take being overheated without damage, but there heavy.

Aluminum
Only use in fresh water or closed cooling system, less weight, can not take much overheating without damage
 

acdc96

Chief Petty Officer
Joined
Apr 23, 2013
Messages
412
I boat in brackish water. LIS. Rarely in freshwater with this boat. why not aluminum in salt? Corrosion?
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,583
I boat in brackish water. LIS. Rarely in freshwater with this boat. why not aluminum in salt? Corrosion?

More for corrosion then anything. You need to make sure your zincs are checked and replaced when necessary, most folks shy away from regular maintenance so aluminum can be bad. Here are a couple of links and reads which may help. Keep in mind those who are selling manifolds most often have a slant toward selling

http://www.perfprotech.com/blog/arti...aust-materials
http://www.*****************/boat-for...rsus-Cast-Iron Edit iboats didn't like this one
http://forums.iboats.com/forum/engin...nd-best-brands

Google aluminum marine exhaust manifolds in salt water
 
Last edited:

acdc96

Chief Petty Officer
Joined
Apr 23, 2013
Messages
412
thanks a lot for the info! A add on my local craigslist listed two brand new cast iron exhaust maniflolds for $130 each with the hardware. Gonna try to get them for $100 each.
 
Top