Aluminum vs Steel to make exhaust heat shield.

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The heat shield between the exhaust manifold and the spark plug wires has rusted away on my truck. I am going to make new ones from either a sheet of aluminum or a sheet of galvanized steel I can pick up from tractor supply. The shielding is not in contact with the exhaust manifold so we are working with mostly radiant heat between the exhaust manifold and the heat shield. I like the idea of using the aluminum for its anti corrosion properties but i am concerned that the exhaust manifold might get too hot for the aluminum. Below are pictures of the heat shields i am going to make. As you can see the aftermarket shields are made from galvanized steel. Also the shielding is in very close proximity to the exhaust manifold and probably touching it in some places. This vehicle gets driven in the salt belt. What material would you use?

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Thats one clean mouse motor. I`m thinking of trying stainless, thin gauge for the 327 I freshened up this past summer. Please post what you wind up with.
 
For that location...I would absolutely use SS over aluminum. You're in track with the exhaust temps at that location being too much for aluminum...otherwise, companies would offer performance headers made of aluminum.
 
Steel. Just a thought, could you use 2 layers of the shield, one on top of the other? And just maybe insert a thin layer of exhaust manifold cladding material cut to size between the layers? For better heat protection for your plug wires.
 
Had same problem on a 4 cyl camry- the 94 camry had the motor mount right next to the one exhaust pipe it failed (from the heat I think]. PUT A cambell big soup can around it part that faced the mount - with a few holes in it to allow some heat loss but it stopped very high temp. so steel is what I used. , warning - but was ugly , not like your motor- this at 150,000 miles droveit to 230,000 no issues.
toyota moved the motor mount in next year or so - toyota is good on tweaking stuff like that.
I would put some 1/2 inch holes in it to prevent xs heat , think 2 hours at 75 mph on interstate-
are heat shields stock on that car?
 
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Aluminum would be fine for a shield from a thermal perspective. It's not as though the shield is carrying the full thermal load of the exhaust like a header would, nowhere near that.

However, aluminum isn't quite anti-corrosive unless it is anodized, but often you find people using a significantly thicker sheet due to the light weight and to help reduce fatigue cracking. I mean that sitting in open air you will get a better result than bare steel but salt will eat it up too.

Stainless would be the better material to use, but if aftermarket shields exist, why go to the trouble? How many years did the originals last before rusting out?
 
I don't know how much time is involved, but I'd think that aluminum would be easier to work with then steel. The worst that could happen is that they warp or sag. Aluminum melts around 1200F, but since this is a shield and doesn't have to hold anything or provide strength, I'd argue that it could probably exist at 600F okay.

Heating galvanized can be toxic, but I doubt it's an issue underhood, unless offgas makes it into the hvac.

Depending upon what conditions (salt, rain, etc) this will see, the material may be less important. Steel may be fine given proximity to some significant heat sources.
 
Stainless or paint the galvanized with ceramic spray paint.

You could also make it out of aluminium and anodize it yourself if you wanted to, from what I understand the process is very similar to electrolysis for steel. You could probably just use aluminium household flashing, I don't think it needs to be that thick.
 
dont forget DONT use cad plated bolts, but DO use anti-size compound on threads. and tighten bolts to 70-80% of full torque at first then take them on down after 4-6 full heat cycles.
 
I finally got around to making some heat shields. I bought a sheet of galvanized steel from home depot. I flattened the old heat shield and traced it onto the new steel. I then used a variety of tools to bend the new metal into the proper form. They came out great and cost under $6. Here are some pictures of the old rusted one I flattened out to make a template and the made parts.

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Very nice sheet metal Fab Sir! Based upon all that rust on the frame, I would say you have the salt situation just as bad or even worse than here in MN....
 
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