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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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Discussion Starter #1
Can someone please tell me the purpose of the butterfly on the 352 exhaust manifold? Mine is stuck in the open position, and there is no evidence of any linkage to operate it, save for the ball end at the valve itself. Thanks, Seth
 

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Unimog_404.113_1970
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perhaps its one of those valves that redirect the exhaust fumes through the intake, so the engine heats up faster ..

in that case its supposed to be an "spring" made of bi-metal, which opens the valve when the engine is hot ....

or i just got you totally wrong ... (little confused by the "butterfly"[?])
 

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mogless, except for my friends MB4-94. And a bunch of other diesel junk.
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2,512 Posts
Discussion Starter #3
So, by butterfly I mean the throttle plate type item that can restrict exhaust flow at the outlet of the manifold. There's no provision for the exhaust to be rerouted elsewhere to preheat anything, and no sign of whatever operated it. The truck seemed fine without it, just thought that maybe it might make some improvement. Thanks in advance, Seth
 

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Sounds like an exhaust brake. The backpressure created by the exhaust brake helps increase the amount of braking created by the engine. This is real useful when heavily loaded and on a steep downward grade to reduce the use of the service brakes.
 
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