Manifold/riser kit

[tonyjh63]

So a local mechanic is telling me I need a new manifolds and risers kit for my 1999 Merc 4.3 (2bbl). He says mine have the infamous "foghorn" style which Mercruiser used for only 4 years, due to problems from bad design? How much should I be looking at to replace basically my entire exhaust system (I guess)?
Geek, with the price he's telling me, seems I could just buy a used engine and drop it in...

 

[Lou C]

The Barr Marine aftermarket conversion kit is $1200 plus labor. A new engine by the time you’re done if you’re paying someone else will be about $5000. Those were a bad design they couldn’t get consistent wall thickness so there were a lot of failures (water intrusion).
My OMC also had the one piece units while I never had problems with them because I’m in salt water you have to replace them every 5-7 years or you’ll have water intrusion eventually.
I made up my own conversion using Barr Marine aftermarket manifolds and elbows and Volvo Penta exhaust pipes and hoses. So my engine is on its 4th exhaust system don’t feel bad about having to replace it once.

 

[tonyjh63]

The Barr Marine aftermarket conversion kit is $1200 plus labor. A new engine by the time you’re done if you’re paying someone else will be about $5000. Those were a bad design they couldn’t get consistent wall thickness so there were a lot of failures (water intrusion).
My OMC also had the one piece units while I never had problems with them because I’m in salt water you have to replace them every 5-7 years or you’ll have water intrusion eventually.
I made up my own conversion using Barr Marine aftermarket manifolds and elbows and Volvo Penta exhaust pipes and hoses. So my engine is on its 4th exhaust system don’t feel bad about having to replace it once.

Thanks for your reply!! Do you have a link to that kit? I went to the Barr Marine site, but can't seem to find it. Is the kit complete? What else might I need?

 

[Lou C]

Look for it on Lighthouse Marines site

 

[Lou C]

Barr Conversion Kit for Mercruiser V-6 GM 4.3-Liter from One Piece to Two Piece

Barr Conversion Kit for Mercruiser V-6 GM 4.3-Liter from One Piece to Two Piece

www.marineengineparts.com

I got my Barr exhaust from them they are local to me. If you’re at all handy you can do this yourself in a few hours

 

[tonyjh63]

Can anyone explain what this "dry joint" vs "non-dry joint" stuff is, and maybe tell me what I might have/need? Thanks!

 

[achris]

Can anyone explain what this "dry joint" vs "non-dry joint" stuff is, and maybe tell me what I might have/need? Thanks!

Mercruiser exhaust systems.

Exhaust systems 101 Mercury’s introduction of ‘dry-joint’ manifolds (and elbows) seems to have caused more confusion than it needs to. So let’s try to unpack that confusion, and understand what is essentially a very simple system. Before we go much further here’s a picture of the various parts...

forums.iboats.com

 

[Lou C]

The kit I posted above uses the older style wet exhaust joint, but enables you to make the conversion without changing the Y pipe (which requires pulling the engine). Not sure if its possible to do the conversion with dry joint manifolds & elbows.

 

[achris]

The kit I posted above uses the older style wet exhaust joint, but enables you to make the conversion without changing the Y pipe (which requires pulling the engine). Not sure if its possible to do the conversion with dry joint manifolds & elbows.

Yes it is.

Instead of the kit for the 2 piece wet joints, use the parts I list in my exhaust shutter thread for 7° elbows.

What the heck, here's a list of parts required.

V6 Dry-joint Manifolds: –864612T01
Manifold gasket: 27-99757
7° dry-joint Exhaust elbow: –864309T02
Elbow gasket (for raw water cooled): 27-864850A02
V6 Intermediate elbow (with NO riser): -14478T01

Rubber tubes.
Upper: 32-44348001
Lower: 32-14358001

Hose clamps: 54-815504372 (you'll need 8 per side)

Chris.........

 

[tonyjh63]

While on the subject of these manifolds and risers, I have another, more general question: why do we even have this system wherein the exhaust manifolds are cooled by water? Cars don't need these, so why do we have them on our boats? Do inboards have 'em? Is it a heat ventilation issue?

 

[achris]

While on the subject of these manifolds and risers, I have another, more general question: why do we even have this system wherein the exhaust manifolds are cooled by water? Cars don't need these, so why do we have them on our boats?

Easy answer... Heat. Ever put your hand near a car's exhaust manifold when under full load? She's warm, mate! Too warm for a fibreglass (or aluminium) dogbox. Add an enclosed space, with a volatile liquid (petrol) and you want to do everything you can to keep that place cool.

Do inboards have 'em? Is it a heat ventilation issue?

Yes, inboards also have water cooled manifolds. Infact, it's the same manifold as your stern drive engine.

It's only when you get to MUCH bigger vessels (like SHIPS!) will you find a dry exhaust. And then the entire system is lagged up to the yingyang to keep the heat out of the engine room and trunking to the funnels.

Chris.....

 

[tonyjh63]

So anyone have a ballpark guess on what it should cost to have this kit installed (basically replacing my old manifolds/risers with this new stuff) - parts, hours of labor, etc.? Thanks!

 

[achris]

Using genuine Merc parts, you're looking at around $1100 per side for the parts. Labour to remove the old and install the new would be, depending on access, around 2 hours per side, if everything goes well. If the Merc price tag balks you, then you could try one of the aftermarket conversion kits, but I can only find wet-joint conversion kits, and if you're going to ditch the batwings, put dry-joints on....

Chris......

 

[tonyjh63]

Using genuine Merc parts, you're looking at around $1100 per side for the parts. Labour to remove the old and install the new would be, depending on access, around 2 hours per side, if everything goes well. If the Merc price tag balks you, then you could try one of the aftermarket conversion kits, but I can only find wet-joint conversion kits, and if you're going to ditch the batwings, put dry-joints on....

Chris......

Thanks for the reply! Kinda figured I was getting ripped off, and you've confirmed it.

 

[tonyjh63]

Thanks for the reply! Kinda figured I was getting ripped off, and you've confirmed it.

Eh...ok, "ripped off" is probably a bit harsh...I really hate posting negative stuff online, as there is plenty of that already!

 

[Lou C]

Are you in a freshwater region or salt? If fresh you may do fine with the aftermarket wet joint units that come in the Barr kit and the parts price is about half what the Merc OEM dry joint goes for. In fresh you don’t get near the corrosion we see in salt water regions. If in salt then yes the dry joint should be less prone to trouble but the elbows can still rust through if not replace on time.
I installed my conversion using Barr aftermarket OMC/Volvo wet joint units with Volvo Penta 90* down pipes and hoses to connect to the Y pipe in 2017. I had the manifolds off in September to get access to replace my old leaky steering actuator, and they looked fine no rust trails in the exhaust ports that mate up to the cyl heads…

 

[Lou C]

here's what can happen if you leave them on too long in salt water, these would not have leaked at the water passage but the elbow exit itself rusted through. Not mine a pic I found on the 'net, prob in a heavy salt region.
When I had mine off I hooked them up to the water hose to watch for any leaks and they are fine after 4 years.
On my old OMC batwings after 5.5 seasons one of the 4 exits was clogged, but no really bad corrosion like this, but our water may not be as salty...
The ironic thing is that those elbows would have looked fine from the outside, all the rot was under the hose, hidden from view. That's why here we usually inspect by 5 seasons or so.