Exhaust header colour

Mopar Big Block Talk
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AndrewP
Posts: 715
Joined: Sun May 05, 2013 11:14 am
Location: Perth, W Australia

Exhaust header colour

Post by AndrewP »

Evening everyone,

The engine and box is all now out of the car. No major hassles and apart from being a huge lump of cast iron, and rather cumbersome, it all came out in one go, incident free.
I'll work through the rebuild in due course, but one thing I've noted immediately is firstly the passenger side header is cracked, but also the noticeable difference in header colouring.
This is the drivers side header..fairly uniform in colour (side not cracked).
IMG_20200522_160245_copy_800x600.jpg
IMG_20200522_160245_copy_800x600.jpg (190.63 KiB) Viewed 2019 times
The passenger side is noticeably different with colour variations. This has a large crack across the middle pair of outlets.
IMG_20200522_160259_copy_800x600.jpg
IMG_20200522_160259_copy_800x600.jpg (141.66 KiB) Viewed 2019 times
This may point to one or more of the bank not firing properly or something along those lines (one of the reasons why I pulled the engine was that I was not happy with the smoothness and power delivery).

Any thoughts?
Andrew P
Perth, Western Australia.
Interceptor Mk3 #1284312
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Blue-SP
Posts: 120
Joined: Thu May 11, 2017 9:09 am
Location: Hampshire

Re: Exhaust header colour

Post by Blue-SP »

I am no expert but do you know how long it may have been cracked for? It may have been a batch problem as looking through my cars history the near side exhaust manifold was changed under warranty when the car was 9 months old.
Another possible cause is the near side is closer to the curb and gutter so continual spray from puddles in the rain could mean more oxidation than the offside which sits in the middle of the road on the high side of the camber and therefore less spray.
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AndrewP
Posts: 715
Joined: Sun May 05, 2013 11:14 am
Location: Perth, W Australia

Re: Exhaust header colour

Post by AndrewP »

Ive known its been cracked for a while, but the 'tissue test' didnt show any large amounts of exhaust gases escaping, so I dont think that if it is leaking, that its a large crack or indeed, even cracked down to the insides (can they crack on the surface and not all the way through?).

Fortunately where I live, we dont get much rain, and so the car generally stays dry. When it does rain, (as it happens we have a large storm bearing down on us tonight) it RAINS proper rain :) and the car does not venture out in that.

Anyway, when the heads are off, I should be able to diagnose better. Just wondering if (assuming the variance of coloration) would indicate cooler combustion temps, which would indicate incomplete combustion or something else.

Cheers
Andrew P
Perth, Western Australia.
Interceptor Mk3 #1284312
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slotcarone
Posts: 1658
Joined: Sun Aug 29, 2010 1:38 pm

Re: Exhaust header colour

Post by slotcarone »

I would not worry about the varying color of the rust. That crack most likely does go all the way through however if exhaust was escaping there would be black around the crack. Typically these manifolds are coated with carbon inside and my guess that is preventing the exhaust from leaking through the crack. I would replace it! If you are putting the cast manifolds back on get some cast manifold paint on them before you install them. :)
1972 Interceptor III
133-5612
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