Heat shield, engine heat guage?

[az]

Is there any correlation between the darkness of the exhaust manifold heat shield and how hard a truck was run, how hot it got?



Speaking of used trucks here I see some there look like the picture below, yet others with the same miles that look as if it brand new, silver with no discoloration.



So, can this be used as a very rough guage on past history?



Here are two truck, same year with similar mileage, about 140K each, big difference



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[Bob4x4]

My heat sheild did not discolor till I towed with it... ... ... .



Bob

 

[az]

My heat sheild did not discolor till I towed with it... ... ... .



Bob

Good info, so if I was looking for a used truck then I might look at the shield first.

 

[Prairie Dog]

I've towed with mine alot (only 7k lbs though), it still looks like the second picture.

 

[JFaughn]

Sometimes the dealer will put a shinny coating on a pressure washed eng. to make it look better , than that will change with heat , either that or the discolor from heat .

 

[mberry]

Mine has a few spots on it where it touches the manifold. I have an ATS exhaust manifold and have towed with it, but not a lot.

 

[DPKetchum]

From what I can see the front part of rocker cover/head is als stained. Someone used something on it and it stained and cooked. At least that what it looks like. As well as that engine in first photo is slimy looking. 2nd engine is clean but dosen't look like any goo put on it.