Discoloration on TAMD 75

[Tbw5959]

hello All, quick question, going to survey on a 2004 466 in a couple weeks, but saw this 'discolored area' / overheated? area on 1 of the engines, and wondering what that might be?

Maybe others have seen this same thing and figured it out or have a theory about it?

Please see pic attached, any ideas/recos? Thanks much

[Carpediem]

My engines have the same issue, The paint is just burned off so the cast iron manifold is rusting. At some point you will want to wire brush the area and repaint. Keep and eye on it for signs of an exhaust leak, you will see soot if there is a leak. I don't think it is a sign of any thing serious.

[Viper]

I agree, it's exhaust, it gets hot. My biggest concern would be the mounting studs. They're looking like they might be getting to a point where they'll get so rusty they'll break if you ever have to get the nuts off, so you may want to be proactive and have the studs replaced. Other than that, brush the area and coat with high heat paint.

Hope the survey goes well. Keep us posted.

[Tbw5959]

Yep, surveyor confirmed that's exactly what has happened / is happening -- uncooled area, gets very hot (FLIR showed ~400 deg F), paint bubbles off, then metal rusts.... Volvo Tech re-confirmed and said 'they all do that'..

[Carpediem]

This is a winter project for me on my 506, I am going to remove the turbos and induction pipes and recondition them, there are a few layers of burned discolored and flaking paint on the compressor section that really bothers me. The whole engine room actually is getting totally refreshed. The aluminum plates that the engines are mounted to are all blistered with corrosion under the black paint, going to be a miserable and tedious job but it will be worth it in the end.