Replacement Exhaust Manifolds for Merc 496

[AShipShow]

Does anyone have any recommendations for a decent aftermarket option for exhaust manifolds? I'm thinking of replacing them on my 2006 project boat and I don't know if they've ever been replaced so looking at doing it as a preventative measure, but I don't love the almost $1500 price tag for OEM merc ones.

I saw that Barr marine makes them, but haven't seen any other options.

Is there a good way to inspect these? theres no open water jackets like the older "wet" joint on the SBC motors that you could see how much corrosion is in the water jackets.

 

[Scott06]

Does anyone have any recommendations for a decent aftermarket option for exhaust manifolds? I'm thinking of replacing them on my 2006 project boat and I don't know if they've ever been replaced so looking at doing it as a preventative measure, but I don't love the almost $1500 price tag for OEM merc ones.

I saw that Barr marine makes them, but haven't seen any other options.

Is there a good way to inspect these? theres no open water jackets like the older "wet" joint on the SBC motors that you could see how much corrosion is in the water jackets.

Normally Barr is the only aftermarket one that gets OEM like quality marks.

The dry joint is open at two points where it connects to the riser ? cant see in there?

Was it a salt water boat? if it was definitely replace them, if it was fresh water use they will last the life of the boat unless freeze cracked

 

[AShipShow]

Normally Barr is the only aftermarket one that gets OEM like quality marks.

The dry joint is open at two points where it connects to the riser ? cant see in there?

Was it a salt water boat? if it was definitely replace them, if it was fresh water use they will last the life of the boat unless freeze cracked

I don't really know yet.. I haven't removed the elbow or manifolds yet... That being said, even if I can see in there, theres guaranteed to be rust... I think the issue is, theres no way of knowing how much wall thickness remains.

The boat was used in the middle chesapeake, in the DC area, so brackish.

 

[AShipShow]

Didn't think about it until just now, but i just bought a fancy little boroscope... maybe a good opportunity to try it out... maybe inspect the cooling passages as well as the actual exhaust ports for signs of rust..

Still no way of knowing how thick remaining cast iron is tho

 

[Lou C]

If they are original from 2006 and used in brackish water, they should have been replaced at least 8 years ago! I change mine every 5-7 years depending on the hours I have put on it each season.
Barr exhaust is good, just make sure to check the flatness of the sealing surfaces.

 

[Scott06]

I don't really know yet.. I haven't removed the elbow or manifolds yet... That being said, even if I can see in there, theres guaranteed to be rust... I think the issue is, theres no way of knowing how much wall thickness remains.

The boat was used in the middle chesapeake, in the DC area, so brackish.

given the age and use just replace them. My good friend who is in the Chesapeake middle to upper bay they are a wear item.

When you remove the elbows there will be two passages you can look down in. There is a big diff between what you see in fresh only lake use and brackish/salt.

if you look at the pic of these there are two 3/4" ish dia tubes either side of the exhaust port between elbow and manifold. Would assume this is where the water flows between them and should be able to look

MerCruiser 8.1L - 496 MAG Exhaust Manifold

866178T01

www.michiganmotorz.com

 

[AShipShow]

Just took the starboard elbow off and stuck my boroscope in both sides and to be honest I was shocked how good they looked... obviously some corrosion but no flaking rust...
I also reached out to the broker who I bought the boat thru and he said they almost never see failures of those manifolds in DC area... he's also calling it fresh water in the Potomac, but I imagine it's still got some salinity..

I'm taking everything he says with a grain of salt compared to more reliable sources, but to his credit, the water jackets actually looked pretty good.

When I get a minute I'll post some pics from the boroscope

 

[Scott Danforth]

the 8.1 came with stainless elbows. so you dont have to worry about the elbows BARR probably made the castings for Mercruiser as they are one of the OEM casting houses for Merc, Volvo, PCM, Indmar, and Ilmor.

 

[Lou C]

post up some pix!

 

[Scott06]

Just took the starboard elbow off and stuck my boroscope in both sides and to be honest I was shocked how good they looked... obviously some corrosion but no flaking rust...
I also reached out to the broker who I bought the boat thru and he said they almost never see failures of those manifolds in DC area... he's also calling it fresh water in the Potomac, but I imagine it's still got some salinity..

I'm taking everything he says with a grain of salt compared to more reliable sources, but to his credit, the water jackets actually looked pretty good.

When I get a minute I'll post some pics from the boroscope

That may be essentially fresh that far up the Potomac. If thats the case they may be fine to use. What I have seen in manifolds in fresh they get a brown layer of dust on them but no chunks flakes etc.

You can test by filling with acetone which will wick into cracks or pin holes. Again hard to say but if there is no signs of salt water corrosion or lack of winterization you are likely ok to use them.

 

[AShipShow]

the 8.1 came with stainless elbows. so you dont have to worry about the elbows BARR probably made the castings for Mercruiser as they are one of the OEM casting houses for Merc, Volvo, PCM, Indmar, and Ilmor.

Sorry, I guess what I said is confusing now that I read it back... I removed the elbow, but I stuck the boroscope in the manifold, not the elbow (since its stainless, I wasn't worried about it).

Good to know about Barr, at least saves me a couple hundos.

 

[AShipShow]

That may be essentially fresh that far up the Potomac. If thats the case they may be fine to use. What I have seen in manifolds in fresh they get a brown layer of dust on them but no chunks flakes etc.

You can test by filling with acetone which will wick into cracks or pin holes. Again hard to say but if there is no signs of salt water corrosion or lack of winterization you are likely ok to use them.

Yea, the inside of the manifolds is basically like a thin brown dust kinda like you described... There are a few areas that look like they are darker, but its weird, they are like kinda shiny, not so much a normal rust look.

 

[Scott06]

Yea, the inside of the manifolds is basically like a thin brown dust kinda like you described... There are a few areas that look like they are darker, but its weird, they are like kinda shiny, not so much a normal rust look.

then it was fresh water use, if they pass acetone I would use them

 

[AShipShow]

Heres a couple boroscope images.. Last image is the worst one, but I'm not so sure its flaking rust vs dirt lodged down in the bottom corner.

 

[Lou C]

Those actually look good!

 

[nola mike]

Are you

Just took the starboard elbow off and stuck my boroscope in both sides and to be honest I was shocked how good they looked... obviously some corrosion but no flaking rust...
I also reached out to the broker who I bought the boat thru and he said they almost never see failures of those manifolds in DC area... he's also calling it fresh water in the Potomac, but I imagine it's still got some salinity..

I'm taking everything he says with a grain of salt compared to more reliable sources, but to his credit, the water jackets actually looked pretty good.

When I get a minute I'll post some pics from the boroscope

Are you Chesapeake or upper Potomac? Very different salinity. Chesapeake Bay is salt, Potomac by DC pretty much fresh water.

 

[AShipShow]

Are you
Are you Chesapeake or upper Potomac? Very different salinity. Chesapeake Bay is salt, Potomac by DC pretty much fresh water.

I'm neither lol... The hailing port on the boat is Washington DC (but that could be anything, doesn't mean where it was used)... The boat was stored in Occoquan, VA, maybe 20mi down the potomac from DC, but still quite a ways up from the mouth at the chesapeake.

Edit: I just found a maryland.gov site that has salinity measurements from what I assume is gauges or buoys and where the boat was used is essentially freshwater... Salinity levels less than 1ppt... The mouth of the patomac is about 12ppt and atlantic at mouth of bay is like 30ppt.

So my broker was right, its basically fresh water.

 

[AShipShow]

@Bondo I can't believe they haven't made you you're own "ayuh like" button by now

 

[Bondo]

@Bondo I can't believe they haven't made you you're own "ayuh like" button by now

Ayuh,....... I know I've single digit typed it thousands of times,.....

Years ago, it was mentioned that someone smarter that me, could somehow save my opening line, so that 1 key on my keyboard could pop it into a dialog box,..
Coulda used it 20 or 30 thousand(Maybe 40, or 50,000) times by now,....

For yer topic, I'd clean up what you've got, 'n slap on some fresh gaskets, then go Boatin',......