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What are these spots in my exhaust manifolds?

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What are these spots in my exhaust manifolds?

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Old 05-16-2019, 09:39 PM
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Default What are these spots in my exhaust manifolds?

I pulled my risers to work on some wiring to find these white spots in my exhaust manifolds.

The attached picture is looking down into the top of the exhaust manifold where the riser attaches. These same spots are not in the risers at all.

The boat was run for a short period of time (like a couple minutes) a couple weeks ago and then has been sitting.

Any idea what this is? Something to worry about?




Thanks,
Russ
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Old 05-16-2019, 09:47 PM
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the white spots are from water,you have a reversion issue.
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Old 05-16-2019, 09:52 PM
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thats f'ing awesome. Your sure on that? I was really hoping that was not the case.

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Old 05-16-2019, 10:17 PM
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A cold engine can also create these vapor spots. One by product of combustion is H2O. It's probably been there all along. I've seen it in my exhaust for the last 12 yrs. If you pull your risers and see puddles of water, then I would be concerned. Check all gasket, make sure the exhaust is sealed tight. Do your due diligence.
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Old 05-16-2019, 10:20 PM
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Are they aluminum manifolds or iron?? Bet they are aluminum.
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Old 05-16-2019, 10:23 PM
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That's some better news....I'll put down the vodka bottle for now.

I'll run it more and pull them and check for puddles and double check my risers to make sure they are not leaking. I've got long, S shaped risers and not a huge cam, so I was going to be suprised if it was sucking water.

It's a small block and I am running an XM270HR cam.

Thanks,
Russ
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Old 05-16-2019, 10:30 PM
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Originally Posted by 14 apache View Post
Are they aluminum manifolds or iron?? Bet they are aluminum.
yes, aluminum.
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Old 05-16-2019, 10:30 PM
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Originally Posted by highplainsdrifter View Post
I've got long, S shaped risers and not a huge cam, so I was going to be suprised if it was sucking water.

It's a small block and I am running an XM270HR cam.

Thanks,
Russ
I had dry to the tip TRS tails (3' long) and it would pull water vapor that far. Severity is the biggest issue. Just thoroughly check your system.
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Old 05-16-2019, 10:40 PM
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Found this pic from a previous post of yours.
If these is on your exhaust/boat I wouldn't worry about reversion. A million marine sbc people have run that cam with many different exhausts so we have a good handle on what will work or not.
If this is your t-stat housing I would worry about that for other reasons !

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Old 05-17-2019, 11:11 AM
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Those spots are calcium deposits left from combustion water vapor that has condensed after a short run. Reversion would leave puddles on the manifold floor and streaks down from the elbow. Equally spaced 'dots' of calcium is not reversion. I've been running a slightly bigger cam in a SBC with less sophisticated exhaust for several hundred hours and I don't have reversion.
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