Painted headers

Okay, here goes...
I just received my new Flowtech Headers for my truck. They come with a black painted finish. My question is this - is this painted finish just to keep them from rusting during shipping (because the paint comes off very easily)? Should I paint them with a high-quality header paint before I put them on? Should I sandblast the el-cheapo black paint off before painting them with higher-quality stuff?
I'd rather not take them off every 6 months to repaint, and at the moment I'm too cheap to get them ceramic coated.
Am I asking too much for header paint?
The headers are going on a daily-driven Chevy truck.
If I should re-paint them, what's a good paint to use? I've head that stove black works pretty good, but I'd rather get a different color, puposely designed header paint.
OR, should I quit complaining, and just put them on the way they are, and live with rusty headers?????

Thanks for everyone's advice in advance!!

Darren

Hi, I don't know much about headers or painting them but I have looked into the subject as I'd also like to find an inexpensive way to hide the rust on my own stock headers. A good company to look at is Eastwood. They make several kinds of high temp paints for headers & other uses. Their site is at:

http://www.eastwood.com

Another product is a paint which can be applied right over rust called POR-15. It seems to have a good reputation. You can find it at:

http://www.easycarts.net/ecarts/PermanentRestorationProducts/
http://www.por15store.com

If you're not stingy you can get rid of the paint and have it ceramic coated. Two birds with one stone. :)

I would not use POR-15 on headers. If you drive the truck everyday, there really is no need to use header paint. The heat from the engine keeps the headers dry so rust doesn't have time to form. I drove the same truck with the same unpainted headers for 3 years and there was no more rust on the headers then there was 3 years earlier. But on a more seldom driven car, header paint/ ceramic coatings are a good idea.

Originally posted by enginerd
I would not use POR-15 on headers...

Do you have something against POR-15? Will it not work well? My 13 year old stock exhaust manifold is totally covered with rust. I have no plans to replace them, and I'm stingy, so I was thinking of using a high temp paint to hide the rust. I even plan to paint them in place (if I can find a company that makes high temp paint that's not an aerosol.)

If anything, heat will accelerate the reaction between the iron and oxygen. Dry steel rusts, you know.

Originally posted by Quad250
...I've head that stove black works pretty good...
I tried some on a stock manifold and it was gone in a couple of days. I don't know if it was from excessive heat or the fact that the stove black was over ten years old.

Originally posted by Gasoline Fumes

I tried some on a stock manifold and it was gone in a couple of days. I don't know if it was from excessive heat or the fact that the stove black was over ten years old.

Any paint I've ever seen for stoves or bar-b-ques can't take the extreme heat of exhaust headers. Black paint might just put a coating of carbon on the surface and carbon burns off at high temps. I think a permanent type of paint will either have some kind of ceramic material in it which can bond at the high temps or they might have metal flakes and some kind of binder. Unfortunately, these things aren't going to be on the ingredient list so you have to ask the company if their paint can take these temps.

Originally posted by 454Casull
If anything, heat will accelerate the reaction between the iron and oxygen. Dry steel rusts, you know.

That's true, though damp steel rusts more easily. There are acid vapors in exhaust too that can corrode iron. They don't even need any water to work. Paint can help if it is durable enough but the best protection against rust would be ceramic coating, inside and out.
I've heard that some insulating wraps for headers can actually accelerate rusting by trapping moisture against the metal when it should be allowed to evaporate.

Don't be silly. I have nothing "against" POR-15, but it's used to seal chassis members against the elements and I for one don't know if it's suited to high temp applications. If it's suited to high temp applications, it should be fine but i don't know if it is or not. What i am saying is if you drive it everyday you will not have any problems with rust.

I haven't used POR-15 for anything myself but I hear it's a good product. I don't know offhand if it can take exhaust temps, but if it can, there's a good chance I'd use it. I only know of one other company that sells paint specifically made for the extreme exhaust maniford temps and that is Eastwood. I don't recall how well it can go over rust though. One thing for sure, I'm not taking my exhaust apart just so I can paint it. If I can't do it in place I won't do it at all, it's just not that important to me. I'd like to do it because it could enhance the overall look of my already clean engine.

Are you sure it's not a ceramic powder coat? Because if that's the case, you don't really have much to worry about. Find out what the paint is first.

OK, POR-15 is just fine for use on headers (from thier advertisement). I'll just add that realistically, I've never had a need to protect headers with paint. I drove my truck everyday and never noticed any rust. The only time the headers ever got rust on them was when I had to send the heads out to get a valve job and the truck wasn't driven for a few days.

Originally posted by sciguyjim


That's true, though damp steel rusts more easily. There are acid vapors in exhaust too that can corrode iron. They don't even need any water to work. Paint can help if it is durable enough but the best protection against rust would be ceramic coating, inside and out.
I've heard that some insulating wraps for headers can actually accelerate rusting by trapping moisture against the metal when it should be allowed to evaporate.

Actually, no water no rust. Iron can still oxidize but it can't rust if water isn't involved. Often the water in air is enough for iron to rust, but the higher the temperature the less water will be in the air.

One of the most corrosive products in the exhaust is sulfur, and in todays fuel the sulfur content is very low so there will be little sulfur in the exhaust too. Acid in the exhaust is more a problem in methanol fueled engines.

The best way to protect a header is to made it in stainless, otherwise a non-stainless can be protected with a layer of nickel on them. With ceramic coating the cooling effect of the header will be decreased, this increase the stress in it. And insulating wraps for headers can accelerate rusting as you say.

Isn't iron oxide the product of oxidation between iron and oxygen? That is also what people call rust, right?

Originally posted by 454Casull
Isn't iron oxide the product of oxidation between iron and oxygen? That is also what people call rust, right?

That's right. The oxygen doesn't come from the water, but in fact comes from atmospheric oxygen dissolved in the water. This is why an iron object partially submerged in water will show the most rust forming at a short distance below the surface of the water. This is where the dissolved oxygen concentration is highest.

I've seen very clean iron rust in just a few minutes from water vapor in the air. Heating the iron to evaporate any liquid on the surface just caused it to rust faster. The heat accelerated the chemical reaction. Also, hot air can hold more water vapor than cold air. That's why the air is so humid in the summer and so dry in the winter.

Also, hot air can hold more water vapor than cold air. That's why the air is so humid in the summer and so dry in the winter

You might want to rethink that statement. I think you're right in a round-about way, but not in the way that you seem to be suggesting. Consider: if you have a mass of air mixed with a mass of water vapor, and you heat that air, does the humidity go up, stay the same, or go down?

Originally posted by ivymike1031


You might want to rethink that statement. I think you're right in a round-about way, but not in the way that you seem to be suggesting. Consider: if you have a mass of air mixed with a mass of water vapor, and you heat that air, does the humidity go up, stay the same, or go down?

I haven't actually done the calculations, but whatever they say, the atmosphere isn't a closed system. Hot air will still hold more water vapor on an absolute basis, if not on a "relative" basis.
Ever wonder why static is only a problem in the winter and never in the summer? It's because the static is "shorted out" by the microscopic layer of water on surfaces in a humid environment.
As air is cooled, the first thing to condense out will be water vapor. Next will be the gases which make up our air (argon, CO2, nitrogen, oxygen, etc.)
Now, with air dissolving in water, it's just the reverse. More air is soluble in cold water than hot. That's why warm soda goes flat faster than cold soda.

There isn't any calculating to do, if you're familiar with relative humidity. Relative humidity is the ratio of the partial pressure of water vapor under present conditions to the saturation pressure of water under the same conditions. In other words, it's how much water is in the air divided by how much water the air can hold. If you increase the amount of water that the air can hold, r.h. drops. If you cool the air, r.h. increases, until (as you said in the last post) the water starts to condense out of the air. The water starts to condense when the relative humidity reaches 100% (when the vapor pressure reaches the saturation pressure).

Evaporation rate, and the perception of humidity, are influenced by relative humidity (not absolute). Seasonal trends of relative humidity generally follow the seasonal trends of rainfall, so if you're in an area where it rains more in the summer than any other time of the year, it's likely that the r.h. is higher in the summer. I think that it rains more in the spring and fall, here in Chicago, than in the summer.

In the winter, the dryness that you feel indoors (and the need to run a humidifier), are a direct result of the humidity dropping when air is heated. If the relative humidity was 100% outside, where the temperature was 40degF, and indoors the air had been heated to 72degF, the rel. humidity indoors (without a humidifier) would be 31%. The air would feel noticeably drier, and you'd possibly have trouble with static.

Your statements all sound correct. You are more familiar with relative humidity than I am, so I will defer to you.