Manifold & Riser

Phasma

Phasma2128
Sep 17, 2016
689
West Michigan
Boat Info
2003 360 Sundancer
Engines
Mercruiser 8.1s Horizon
I rebuilt the starboard engine this winter. Mercruiser 8.1s. I am looking at Sierra manifolds and riser. Freshwater boat. The boat is 15 years old. I only absolutely know it’s history for the last 3 years. It does have a known history of having been in saltwater for its first 3 years in Wilmington NC. After that I have no idea until I bought it 3 years ago. Do I replace both engines manifolds and risers? The set on my starboard engine pressure tested ok. The mechanic is still recommending replacing manifolds and risers due to age. Mercruiser wants stupid money for the set that is why I am considering Sierra. My fun money account is a bit drained at the moment. I am usually better safe than sorry but I expect to have to eventually rebuilt port side. Any input?
 
You shouldn't have risers, just elbows. The elbows on your boat should be stainless steel and should not need to be replaced.
 
Thanks Michael. That is exactly what I needed to know. If I am replacing the starboard engine manifolds should I automatically replace port engine manifolds at the same time?
 
I would recommend replacing both, If one is showing signs of failure the other can't be far behind. Replace both and in fresh water you should be worry free for many years
 
I just purchased manifolds for my 8.1's from Michigan Motorz. $460/each plus $100 shipping for all 4. You'll also want to do the gaskets which I got for $43 per. IMO best to replace all 4 and then you're at 'zero' for the set. As others have said your elbows are stainless and should last a loooong time. (I'm in salt and not touching mine)

Here are the manifolds I purchased:

http://www.michiganmotorz.com/mercruiser-exhaust-manifold-p-788.html
 
Definitely replace. So much more expensive when they fail. My 2001 has aluminum risers that were replaced for stainless. Make sure you have the right stuff. I think for your year there are stainless from factory. If a magnet doesn’t stick with I them, replace.
 
I just purchased manifolds for my 8.1's from Michigan Motorz. $460/each plus $100 shipping for all 4. You'll also want to do the gaskets which I got for $43 per. IMO best to replace all 4 and then you're at 'zero' for the set. As others have said your elbows are stainless and should last a loooong time. (I'm in salt and not touching mine)

Here are the manifolds I purchased:

http://www.michiganmotorz.com/mercruiser-exhaust-manifold-p-788.html

Mike:

You might want to plan on replacing some of the sensors that are in the manifolds. I have heard that they do not always want to come out nicely. Just a heads up.

-Kevin
 
I just purchased manifolds for my 8.1's from Michigan Motorz. $460/each plus $100 shipping for all 4. You'll also want to do the gaskets which I got for $43 per. IMO best to replace all 4 and then you're at 'zero' for the set. As others have said your elbows are stainless and should last a loooong time. (I'm in salt and not touching mine)

Here are the manifolds I purchased:

http://www.michiganmotorz.com/mercruiser-exhaust-manifold-p-788.html

Thanks Mike! That’s what I needed. It looks like I can do a direct replacement of all 4 manifolds for the price of two of the Mercruiser manifolds. This forum has saved me a ton of money. I have zero objection to continue financially supporting Club Searay.
 
I just replaced my manifold witch were cast the part store turned me on to buying the conversion kit for the manifold, the manifold are the same but the kit came with all the sensors, valves, hoses and gaskets for the same price as buying just the manifold.
Here is the part # for the conversion kit 866178A02
The kit is used to convert from aluminum manifold to cast manifold.
I now have 8.1 not 5.7
 
I would only use mercruiser manifolds.
Search the forms theres a lot of
Thanks Mike! That’s what I needed. It looks like I can do a direct replacement of all 4 manifolds for the price of two of the Mercruiser manifolds. This forum has saved me a ton of money. I have zero objection to continue financially supporting Club Searay.

I would only use mercruiser manifolds.
There's a bunch of threads on this site with problems people have had using aftermarket manifolds and risers.
 
I would only use mercruiser manifolds.
Search the forms theres a lot of


I would only use mercruiser manifolds.
There's a bunch of threads on this site with problems people have had using aftermarket manifolds and risers.

Could not agree more! The link I provided is for Mercruiser OEM manifolds from Michigan Motorz.
 
Thanks Mike! That’s what I needed. It looks like I can do a direct replacement of all 4 manifolds for the price of two of the Mercruiser manifolds. This forum has saved me a ton of money. I have zero objection to continue financially supporting Club Searay.

Those are actually Mercruiser OEM manifolds for $460! :)
 

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