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8.1L exhaust gaskets

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erich

Regular Contributor
Perhaps someone can explain the purpose of the wing plates used between the manifold and riser, and riser to elbow on the 8.1L Crusader engines with heated risers. The diagram I have seen shows a pass-thru stainless steel wing plate sandwiched between two gaskets. Since the riser and manifold are within the closed coolant/antifreeze section of the exhaust system, what function does the wing plate serve? I can see using the block-off wing plate between the riser and elbow to separate the raw water form the anti-freeze, but why not just use a single gasket between the manifold and riser?
 
To keep the antifreeze separated from the raw water, the connection has to be sealed off. The stainless plates do that, with a gasket on each side.

Raw water cooled engines do away with the plates entirely.

Jeff
 
fastjeff said:
To keep the antifreeze separated from the raw water, the connection has to be sealed off. The stainless plates do that, with a gasket on each side.

Raw water cooled engines do away with the plates entirely.

Jeff
Click to expand...

Jeff,

The question is what function the pass-thru wing plate perform? I know the block-off wing plate separates the raw water from the antifreeze in the closed section. As you say, a raw water cooled engine does use these plates, but why are they used between heated risers and the manifold where the flow is all antifreeze. The only reason I can think of it to trap and fry off any raw water that tries to make its way down the inside of the elbow and riser which should have exhaust gases only and no water at all. But if that is the reason, why not use them on raw water cooled engines?

Erich

PS Part 36 in this diagram is the pass-thru wing plate. http://www.marinepartssource.com/crusaderpb/81-34.asp
 
Last edited:
my parts listing shows them as "shim plates"...and you can't tell much from the drawing.

Your theory may have some merit but without having one on hand to inspect, its really hard to say...

There's no need for it from a cooling function and I'd be hard pressed to justify any "alignment" in theat area of the exhaust being critical ehough wo need a "shim"... you can always call Crusader's tech line and ask...they are a wealth of knowledge.
 
makomark,

I was unable to find a tel # to call Crusader or PCM support, so I sent them an email and the reply I just got today was that these wing plates were an upgrade to the older setup and the "wings", pointed up, are there to catch condensation and prevent it from going further down into the engine, but allowing it to dissipate from the heated plates.

Erich
 
See, even us old dogs can learn new tricks....

In the grand scheme of things, I would leave them out as they really won't make a big difference....given the installed angle of the exhaust, I doubt that the wings would "catch" any volume of condensate that would matter...just my two cents...
 
mark,

I am not sure what you mean by the installed angle of the exhaust. On my boat with V drives the engines are fairly level so with the exhaust in the center of the manifold, riser exhaust port is fairly perpendicular to the water line. Crusader tech support said "we found it to be a great help for this issue" where the issue is condensation traveling down the exhaust. Thanks for your comments.

Erich
 
I see a helluva lot more inline gears than V-drives....and they have a pretty noticeable slope. Either way, a small lip or "wing" isn't going to retain a lot of condensation...but if the factory is going to invest in it, there has to be some return on their investment...Glad you got it from the source..
 
Obviously all 8.1L Crusaders are not installed with V drives, but for the small cost of these plates, I will be using them this spring.

Thanks for the input Mark.
 
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