Need this part #

[tank1949]

My boat has been retro-ed to closed cooled MC V8s. However, I had to tear up exhaust manifold/riser gaskets to remove motors in order to replace a rotten transom. The riser gaskets were made out of a dark gray solid fiber (no passageways) that sandwiched a flat piece of SS (maybe 30-45 thousands thick) . This extra metal gave strength to keep antifreeze from leaking into the riser and hot exhaust gasses getting by. I need MC or Sierra part no. Motors are pre 1995 (no electric fuel pump). Carbureted with TB 5 ignition system. THX

 

[Fun Times]

What liter size is the engine? Serial number handy?

It probably be,

10

27-8637251 https://www.mercruiserparts.com/bam/subassembly/31835/1014/190

GASKET

41811

SS/ACT

$15.90

$15.51

2

But without more info, it's a guess.

 

[Bt Doctur]

If your SS plates are in good condition reuse them with a standard gasket above and below

 

[achris]

It's unusual to see the SS plate on a later engine. Normally all that's there is the gasket for the closed cooling, 27-41811 (for centre riser manifolds), and that is just fine to keep coolant, exhaust gases and sea water in the places there are supported to be. I have run closed cooling on my previous engine, just using that gasket, and that lasted 12 years before I sold it without any problem.. As have a few of my friends. You don't need the SS plates.

Chris......

Edit: 27-41811 supersedes to 27-8637251.

 

[tank1949]

Thanks to all! The gasket(s) and ss plate (very thin) are fused together as one gasket. I am guessing that the metal part is about 35 thousands thickness. Motors are 5.7 Chevy made into strokers. I am guessing that former owner used an open cooling exhaust manifold and made it a closed cooling type, since they seem to be more available. I have some .06000 ss plate I could cut, drill and fabricate but if I could buy what I needed, that would speed things up. I will examine Fun Times' suggestion.

 

[achris]

'Open cooling' and 'closed cooling' exhaust manifolds are one and the same thing. All that changes is the gasket between elbows and manifold. If you're running closed cooling, you use a block off gasket. If it's open cooling, a flow through gasket... That's the ONLY difference (in the exhaust system)...

 

[tank1949]

'Open cooling' and 'closed cooling' exhaust manifolds are one and the same thing. All that changes is the gasket between elbows and manifold. If you're running closed cooling, you use a block off gasket. If it's open cooling, a flow through gasket... That's the ONLY difference (in the exhaust system)...

Shouldn't these Block off gaskets have metal in the middle for support. I have examine several gaskets advertised but none describe metal sandwiched by 2 fiber gaskets. I have also seen MC exhaust manifolds that were indeed closed or blocked off (cast that way) where they connect to risers. Mine are not. Former owner had the sandwiched gasket, but he cannot remember where he purchased them. Perhaps I will phone Sierra and see what they offer. My other option is just to fabricate some ss as a backbone for the fibber gaskets. THX

 

[achris]

Shouldn't these Block off gaskets have metal in the middle for support. I have examine several gaskets advertised but none describe metal sandwiched by 2 fiber gaskets. ...

No, the gasket itself has sufficient strength to not need any metal sandwiched in it...

... I have also seen MC exhaust manifolds that were indeed closed or blocked off (cast that way) where they connect to risers. ..

No, no, no... (Doesn't anybody read what I post?) ALL Merc exhaust manifolds can be either raw water or closed cooled... I suspect what you looked at are wet-joint and dry-joint manifolds, which has NOTHING to do with whether they are open or closed cooled. (see below).

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

 

[achris]

...where they connect to risers....

Elbows.

 

[tank1949]

No, the gasket itself has sufficient strength to not need any metal sandwiched in it...

No, no, no... (Doesn't anybody read what I post?) ALL Merc exhaust manifolds can be either raw water or closed cooled... I suspect what you looked at are wet-joint and dry-joint manifolds, which has NOTHING to do with whether they are open or closed cooled. (see below).

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

THX!!!! I admit I am confused! Except this boat all of my previous MCs were raw water cooled.