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Riser to manifold gasket?

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Stevefish

New member
1994 Mercruiser 5.7 V8 350, carburettor. Engine serial OF418132. Raw water through manifolds and risers, coolant heat exchanger.
I am banging my head against the wall with this one! I have looked and tried everything but still unsure. Which gasket do i use between the riser and manifold?
is it the four slot or two slot with pilot holes. Desperate for a solution.
Steve
 
When you have a heat exchanger it is called CLOSED COOLING SYSTEM Period! Do not listen to anyone else who disagrees.

First, lets clarify what parts you have.

Exhaust manifold
Elbow

Is there a small "riser" in between the two? This is a spacer that can range from 2" to possibly 12" to raise the elbow (above water level)

If no riser then the manifold surface gets the stainless steel BLOCK OFF gasket. No water hole passages, I am not sure if it is sandwiched between two non metal gaskets but if it was not when you took it apart then you dont need them.

When a closed cooling system is used, The 50/50 antifreeze is circulated through engine block/heat exchanger and exhaust manifold only. The raw water is circulated through the heat exchanger (to cool the antifreeze) and is also sent to the elbows. ( this has to happen to keep the exhaust gases cooled as they pass thru the down tubes and rubber boots connected to the down tubes.

Item 10 only for closed cooling NO RISER so its manifold to elbow

Item 8 if there is a riser (manifold to riser)
Link

 
And closed cooling comes in two flavors- half and full; the latter includes the exhaust .acids om the closed side...
 
looks like i am confusing things! i previously mentioned a stainless elbow. This elbow was at the water inlet to the cast iron exhaust manifold, not an actual stainless exhaust elbow.
Also i think i misunderstood the meaning of a riser. I thought that was the name for the cast iron exhaust elbow.
Hope this next post makes more sense and doesn't pi55 anybody off.
1994 Mercruiser 5.7 V8 350 carburettor Serial: OF418132.
Cast iron exhaust elbow, mounted directly onto a cast iron manifold (no riser).
Raw sea water runs up through a coolant heat exchanger, then through the exhaust manifold, through the internal ports of the exhaust elbow and out with the exhaust gases. The manifold and elbow have four long slotted internal ports for the sea water.
The heat exchanger coolant runs through the engine block only {not the exhaust elbows or manifolds)
My question is: do i use a four slotted gasket or two slot and pilot holes gasket.
Steve
 
Again not good info.

This heat exchanger how big is it?
If it is about 6-8" long, that is not a heat exchanger, it is a power steering cooler.

A closed cooling heat exchanger will be 2- 3 feet ling and 3-4" in diameter.


Please clarify.....

I will add, based on you lack of knowlege of what you are working with tells me you should have had a professional work on your issue.......
Again a second post and still we have to ask what parts you are describing....

"We are gonna need a bigger boat"
 
a picture of the entire engine would help resolve what is-isn't present, especially given errors and omissions so far.

I'd be inclined to say its the basic (economical ) installation with raw water cooling -> the two slot gaskets with the weep holes...
 
kghost said:
Again not good info.

This heat exchanger how big is it?
If it is about 6-8" long, that is not a heat exchanger, it is a power steering cooler.

A closed cooling heat exchanger will be 2- 3 feet ling and 3-4" in diameter.


Please clarify.....

I will add, based on you lack of knowlege of what you are working with tells me you should have had a professional work on your issue.......
Again a second post and still we have to ask what parts you are describing....

"We are gonna need a bigger boat"
Click to expand...
lmao, power steering cooler! since when did a power steering cooler have coolant on one side and raw sea water on the otherside?
You are right i need professional help/advice. So you'd best sit this one out'
 
After rereading your prior post,

If you have RAW water flowing through the Exhaust manifold and out the elbow and NO antifreeze, then as MacoMark said, you will use the gasket with two pass through holes and the small bleed hole as he stated.

The stainless Block off gasket is ONLY used when antifreeze is circulated through the Exhaust manifold so not to allow it to pass through the elbow.
 
If you have raw water running thru the manifolds and out the exhaust elbows, you want the 2-slot gaskets with the bleed holes

MERCRUISER 27-863724, for the OEM parts - just paste the part number in the search box at the top of the page...

The attachment shows the cooling system as you have described it...
 

Attachments

  • FWC Half System SBC 93-97.pdf
    89.8 KB · Views: 57
makomark said:
If you have raw water running thru the manifolds and out the exhaust elbows, you want the 2-slot gaskets with the bleed holesclarifying

MERCRUISER 27-863724, for the OEM parts - just paste the part number in the search box at the top of the page...

The attachment shows the cooling system as you have described it...
Click to expand...
Many thanks for clarifying, really appreciated. Steve
 
kghost said:
After rereading your prior post,

If you have RAW water flowing through the Exhaust manifold and out the elbow and NO antifreeze, then as MacoMark said, you will use the gasket with two pass through holes and the small bleed hole as he stated.

The stainless Block off gasket is ONLY used when antifreeze is circulated through the Exhaust manifold so not to allow it to pass through the elbow.
Click to expand...
Thanks
 
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