Refurbishing stock exhaust

[David T]

This.

I spoke to a few powder coaters that did not recommend powder coating the headers, they all said it won't stand up to the heat that headers endure.

One problem is you can't get the cast iron manifolds clean enough for it to stick well. The other problem is the temperature. While there are special coatings that may not burn off they will discolor. A product like POR-15 Hi Temp can take the heat and will stick even if the surface is not perfectly clean. Or you can just leave it "natural".

[mluder]

Hi had my cast iron headers and the muffler/exhaust pipe assembly ceramic coated about a year and a half ago. Didn't do the crossover as I didn't want to take the time to remove the rear wheel to get it off... Lazy.
I went dark charcoal grey on the headers and a lighter grey on the muffelr. So far it's held up very well... no fading or cracking that I can see.

BTW - If i had to do it over I would have left the tips of the exhaust the original stainless.

Cheers
Steve

[Morpheus]

^ Pics?

[DMC-81]

Today I extracted 3 rusty M10 studs out of the exhaust manifolds in preparation for them to be surface planed.

I did the following to remove the studs:
1) brushed off the flaky rust around where the stud meets the thread opening in the manifold with a wire brush.
2) sprayed WD-40 liberally into the threads.
3) installed 2 of the old nuts and locked them.
4) heated the manifold around the stud until it was hot with a regular propane torch.
5) melted candle wax in the seam between the stud and the manifold. The wax is drawn into the threads and provides extra lubrication.
6) heated the manifold again all around the stud, (but not the stud) until it was smoking and then sprayed WD-40 on the stud. Basically, the idea is to expand the metal around the stud with heat, and cool the stud down with lube to create an expansion/ contraction differential.

Finally, I quickly applied a breaker bar and a 17mm crows foot to the inside nut and rocked it gently to the left. Once the stud cracked loose, I sprayed the lube again and gently backed the stud out, working it back and forth as necessary.

Easy Peasy (for this level of rust)

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[mluder]

^ Pics?

Here's how they looked when I installed them.
IMG_5511.jpgIMG_5515.jpgIMG_5560.jpgIMG_5561.jpg

I'll have to get some recent pics to show how they've held up. I'll try in the next couple of days.

Cheers
Steve

[DMC-81]

Today I extracted 3 rusty M10 studs out of the exhaust manifolds in preparation for them to be surface planed.

I did the following to remove the studs:
1) brushed off the flaky rust around where the stud meets the thread opening in the manifold with a wire brush.
2) sprayed WD-40 liberally into the threads.
3) installed 2 of the old nuts and locked them.
4) heated the manifold around the stud until it was hot with a regular propane torch.
5) melted candle wax in the seam between the stud and the manifold. The wax is drawn into the threads and provides extra lubrication.
6) heated the manifold again all around the stud, (but not the stud) until it was smoking and then sprayed WD-40 on the stud. Basically, the idea is to expand the metal around the stud with heat, and cool the stud down with lube to create an expansion/ contraction differential.

Finally, I quickly applied a breaker bar and a 17mm crows foot to the inside nut and rocked it gently to the left. Once the stud cracked loose, I sprayed the lube again and gently backed the stud out, working it back and forth as necessary.

Easy Peasy (for this level of rust)

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Well, today I continued the task by removing the 12 M7 exhaust studs from the cylinder heads. Here are the driver's side with the old gaskets and studs.

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Similar to the above, I did the following to remove the studs:
1) brushed off the flaky rust around where the stud meets the thread opening in the cylinder head with a wire brush.
2) sprayed WD-40 liberally into the threads.
3) installed 2 of the old M7 nuts and locked them.
4) rapped the end of the stud several times with a hammer.
5) heated the stud until it was hot with a regular propane torch.
6) melted candle wax in the seam between the stud and the head. The wax is drawn into the threads and provides extra lubrication.
7) heated the head all around the stud, until it was hot and then sprayed WD-40 on the stud. Basically, the idea is to expand the metal around the stud with heat, and cool the stud down with lube to create an expansion/ contraction differential.

Finally, I quickly applied an 11 mm combination wrench and gently tapped the other end of the wrench with a hammer to the left. Once the stud cracked loose, I sprayed the lube again and gently backed the stud out, working it back and forth as necessary. If the stud didn't crack I repeated steps 4-7 until it did.

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When I was removing the manifolds I got too aggressive on one of the nuts and broke it. I used a 3/8 size ratchet and tried to force it a bit and it broke easily. So I didn't have enough stud left to lock 2 nuts onto it. So, I used a 7mm stud extracting / insertion tool, instead of the combination wrench.

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Driver's and passenger sides finished.
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I learned that you really have to exercise patience on the 7mm studs and go gently so you don't use too much torque. That's why I just used a combination wrench.

[Morpheus]

I also used that same stud extractor, it saved me a lot of headache when doing this job. Nice work!

[DMC-81]

I also used that same stud extractor, it saved me a lot of headache when doing this job. Nice work!

Cool, yeah it worked great. It'll also come in handy for tightening the new studs in.

[DMC-81]

I prepped the crossover pipe for media blasting by removing the stainless steel heat shielding and pipe plugs today.

I used the same method on the 4 M6 bolts and the 2 plugs. One of the bolts was stubborn ( I thought it was going to break) but the plugs were easy.
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I cleaned the stainless steel shields by first wet sanding with 600 grit sandpaper and oxalic acid, then more wet sanding with 1000 grit and water.

Before:
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After:
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[DMC-81]

Questions for anyone that knows...

Were the crossover pipe and or the catalytic converter constructed of stainless steel (or a blend) or were they purely mild steel?

Has anyone measured the temperature of the manifolds while the car is running, and warmed up?