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Manifolds and Elbows - OEM or aftermarket

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abl1111

Regular Contributor
My manifolds and risers are over due, although all is running perfectly - I have a 2001, 350 MAG MPI 300 HP fresh water cooled engine with original manifolds and elbows.

Just heard a horror story from a guy with the same motor...

Does OEM vs aftermarket matter ? Mercruiser has the ceramic coated ones - any opinions here ? And if after market - what brand and where to buy ?

Thx
 
Depends. I know of boats that are over forty years old that still have the original manifolds and run in the Chesapeake's brackish water and are raw water cooled. Does that mean you don't need to replace yours? No.
Are you in fresh water or salt? I don't know how your FWC system is set up. If you have a full system (block plus manifolds) then you need only worry about the risers. If it's a half system the you will replace both manifolds and risers. The only way to know is to pull it apart and look, so at the very least you'll be in for new gaskets. OEM usually means more expensive but is sure to fit and perform properly. Ceramic coating probably for aluminum so they can be run in salt water. Cast iron OK for both fresh and salt.
 
I bought mine here: inetmarine.com
Decent prices, shipped pretty quick, no complaints.
 
Last edited by a moderator:
I have fresh water /antifreeze running through manifolds - risers/elbows are raw water ( salt )... I know someone touched on this, do I need to worry about the manifolds or just the risers ?

Do I ever have to change the manifolds ? When will I know when ?

Do I have the same worry of water getting into the block as an engine with raw water manifolds ?

Thx
 
abl1111 said:
I have fresh water /antifreeze running through manifolds - risers/elbows are raw water ( salt )... I know someone touched on this, do I need to worry about the manifolds or just the risers ?

Do I ever have to change the manifolds ? When will I know when ?

Do I have the same worry of water getting into the block as an engine with raw water manifolds ?

Thx
Click to expand...
You have what's called a Full Closed Cooling system. (it's sort of a misnomer to call this FWC, but I'm sort of a purist on that.... so forgive me! :D )

Your manifolds should last you for years. How long???? very tough to say!
Changing your coolant as required will certainly help.... keeping the PH balance correct.
The acidity and alkalinity is measured on a pH scale and is very important.
It is best to use distilled water for your 50/50 mixture, because it is pH neutral!

Risers, of course, are subject to the elements of the sea water, and will need at minimum, routine inspection..... possibly replacement!

.
 
abl1111 said:
BTW - is it a detriment to use straight antifreeze and not mix it with water ?
Click to expand...
If we're speaking of Ethylene Glycol, yes!
The boiling point will have been changed, and the ability to transfer heat is deminished I believe!
It may also have an affect on the freeze protection ability.

Use caution today..... some of these containers are being sold as "Pre-Mixed". These do not get diluted!

Either way, I think that you'll want the 50/50 mixture, unless otherwise recommended by the manufacturer.

.
 
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