Header Coating Peeling

Joe:

My apologies with the failure comment. It was not meant to be directed at your organization specifically and really more application related. I have no direct knowledge of how many failures you may or may not have with your products, nor is it of any concern to me. My area of expertise is ceramic coatings, thermal barriers and heat dispersants for performance motorsports related applications in which I have 20+ years of application experience in the area. This is why I offer technical assistance to members on the subject. That said, if you're now counting my posts and are establishing a correlation between your products and ceramic discussions, perhaps that in itself is telling of something...

As you've stated in previous posts, your expertise lies in the area of headers and exhaust manufacturing and not in the outsourced coatings your company uses. So purely from a coatings standpoint I can tell that the pictured damage is purely temperature related. This material is very predictable and does absolute things at absolute temperature thresholds. Hence the reason its been used in the Aerospace industry 30+ years.

So as for remediation of the damaged coating, if the excessive temps were NOT caused by a specific situation or series of episodes in which the tuning was a factor i.e. too rich, too lean, plugged CATS etc or perhaps dyno tuning sessions, there will inevitably be a repeat of the current condition if you're using the same ceramic metallic coating....

 

See that's the problem..... The reason the coating doesn't last in those applications is because those applications have been outside of the recommended temp range. Bright ceramic on a properly tuned engine will last nearly forever..... The number ONE reason headers in that arena die so quickly is because they fire up NEW engines with fresh coated headers and run then too fat or too lean. It only takes 15 seconds to trash the coating in that scenario. Once the pores are open on the coating it will rust fairly quickly.

There are numerous reasons you could bash jet-hot though it wont do you much good since the names and faces have changed so many times over the years, particularly after recently emerging from a 950 million dollar bankruptcy. The biggest issue there is not informing customers on how to properly prep and care for their coatings....

 

As stated, one header acquired multiple, not unsubstantial, rust spots from just sitting on the shelf, never having been installed. One header was fitted to an already running engine that was properly tuned and did not run overly rich. It was clear that the coating failure on the header that was used was due to water splashing on it when the car was driven in the rain. Both headers were brand new mild steel, were prepped by JetHot themselves, and were given their most expensive non-colored coating.

Nowhere did I bash JetHot, although I will not use them again in the future. The OP asked if anyone had experienced coating failures and I, as well as a number of others, offered up personal examples. Perhaps you should read more carefully before commenting.

Finally, I have seen literally dozens of headers and/or exhaust components coated by JetHot, or with similar products from other companies. While I do not know the history of the engines on which these components were installed (to be fair, most were race only engines), in virtually all cases the coating durability was disappointing. I don't know what circumstances would be required for your claim of lasting "nearly forever" to be true, but in my personal experience those circumstances are seldom met in the real world, as I have seen these coatings fail even on show cars.

Your comments would be much more helpful if they included advice to owners and engine builders as to what processes, preparation, and maintenance would be required to achieve the apparently mythical longevity that you claim is possible, instead of taking people to task for reporting their own real world experiences. I do not claim to have any specific technical knowledge about ceramic coatings, but I have been involved in the automotive business for over 30 years and can say that in my own personal observation of real world use cases, the type of coating under discussion is not nearly as durable as those in the coating industry would have us believe. Which is not to say that I am not a fan of coating exhausts and other engine components, only that for me it is Swain and nobody else, after the failures I have observed from other coatings.

 

Okay, I guess we’re disputing semantics. When I hear someone say that nearly every header they’ve seen, from “a” particular company turns to crap at some point, I would loosely interpret this as a form of bashing. Call it what you want, but we can agree that it’s not a glowing review. More to my point, it was a very broad and inclusive observation that this coating almost always fails, which is where I would disagree. The problem with the so called failures that you’ve seen is that there are a multitude of reasons for said results and without seeing the actual header I can only offer an educated guess based on my 30+ years of exposure to similar components. I can then give you some suggestion for improving longevity.

Let’s start with what the perfect pair of headers “should” look like to start. A well coated, ceramic metallic header will appear almost “chrome like” when coated and polished properly. SO, if you see a header in any state of failure in the field that resembles the one in this discussion that is very dull, dingy, grey / white / greenish, rest assured that the header in question has been exposed to some elevated EGT’s. The severity, length of exposure, and repetition of exposure to the temp as well as environmental conditions all play into how much longer the coating will survive. Do not confuse this with minor dulling / oxidation that will occur over the years as the aluminum layer oxidizes. This is easily fixed with a little aluminum polish, which buy the way should be done periodically for general maintenance.

Obviously I have no ability to directly comment on poor workmanship / coating that may have occurred on some of these items. Working under the assumption that they were coated properly, I can tell you that water “splashing” on the headers will not cause a coating failure. Even burnt oil / fuel won’t hurt the coating, but it will stain it. The primary reason for rusting / coating failures in the collector areas of headers is the result of the header design and the ceramic material. Most header designs have the primaries physically touching each other in and around the collector area so there is no way to completely coat these pipes. Even if you get ceramic into those areas they are often too tight to allow for burnishing / polishing of the ceramic. If you can’t polish the material it WILL absolutely rust because the pores of the ceramic are wide open. Subsequently, overheating the ceramic opens the pores as well and allows it too again rust……..The most successfully coated headers are multi piece race headers that have individual primaries and slip on collectors.

Another phenomenon though not really relevant to Ferrari applications, headers from the big box boys, i.e. hooker, headman, blackjack, cyclone, etc. tend to corrode / fail fairly quickly. What we know is that most all of these headers are made and coated in Mexico. There could be some processing issues but there seems to be some underlying “acidic” issue with the coating / processing that's causing a premature failure of these headers.

Now for the number one reason for this coating to fail, tuning related temperature spikes / abnormalities. There are numerous possibilities. Just to get it out of the way, this coating is NOT applicable for turbo or supercharged applications. NOS will have an effect on overall tune. Too lean and too fat are BOTH equally bad. You never want to fire up a new engine or dyno one with a set of coated headers. Additionally, just because your engine is tuned at idle doesn’t mean the mixture and timing is equally perfect from idle to redline. It’s entirely possible, especially with computer controlled EFI applications that there are going to be rich / lean spots throughout the power curve. So the header longevity is contingent on how long and how often you may be in these areas of that rpm range.

In a perfectly tuned engine the coating will typically dull “slightly” about 5-10 inches from the head / flame front area just because this is the hottest part of the exhaust. This is the primary reason SHORT headers rarely hold up, even if the tuning is proper. The majority of the header is exposed to the flame front and there is not enough header to dissipate the heat.

As for up keep and maintenance, it’s a good idea to polish them periodically to protect them from corrosion and keep them looking good. Storing them in garages with cement floors and high humidity will obviously expedite corrosion, particularly on those with compromised collectors or headers that have already been overheated. Keep in mind that the rust on headers is NOT always from the header itself. Often times iron dust, particles, brake debris, etc. will settle on the headers and corrode. This is where periodic polishing will help the longevity.

In conclusion, some food for thought with regards to Swaintech / plasma spray type thermal barriers. This type of thermal barrier comes with both pros and cons as well and as you can see from the pics below, it’s not kryptonite. The biggest falsity here is the “thicker is better” mantra and the reference to .015 thickness. Most understand that molten mixes of whatever you want, typically zirconia / aluminum in this scenario are spewed at your parts which offers minimal corrosion protection. Which highlights the first problem; you can NOT coat the ID of most parts and certainly any headers. It’s nearly impossible. The material finish is very porous and rough similar to 24-36 grit sandpaper. Therefore, to say the material is .015 this is false. How do you measure the thickness of 36 grit sandpaper??? You have peaks and valleys and a whole bunch of air. So to just take the gap between the peaks and valleys is misleading. The bigger issue with the porosity of the finish is when you start having any oil / fuel spills leaks etc. It’s doesn’t take long to get enough heat in the exhaust to ignite these….Just last year at one of the SAE college events a car with either zircotec or swain tech coated exhaust ended up in a ball of flames because oil got saturated on an exhaust tube. The white ONLY color would be a positive or negative based on personal taste, though it rarely stays a “clean white”.

Pics:
1) what Metallic Ceramic should begin life as

2) Fresh set of ID/OD coated headers installed on new engine. Headers discolored in less than a minute due to LEAN tuning on start-up.

3) Jet-Hot, the effects of simoltanious lean and rich tuning conditions on a supercharged V-8 application.

4) Failed Swaintech white lightning coating.
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EGT on my duramax, yep I know about that

Coat dude PM your info if your a coater to do my duramax stuff

 

This last one is the final stage of coating failure - sacrificial de-lamination stage. Jet-Hot coated these for a 6.6 turbo diesel Duramax. This is what they look like after 30 minutes on the dyno....

Multiple problems here:

1) first and foremost, this coating should NEVER go on hot side turbo parts

2) the header is too short. Even in a normally aspirated, perfectly tuned world, this header would likely fail because it's just too small and is CONSTANTLY exposed to the flame front.
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Hopefully you determine there was a glitch somewhere and you can get that coating to hold up.

 

even after getting them fixed I would recommend header blankets...not for the headers sake but to reduce heat damage to other parts

 

CoatThis, apologies for taking your comment out of context. It's clear now that you did not mean it in the way I took it.

And thanks very much for your informative post. It may well have helped identify the root cause of failure on the two headers I mentioned. In both cases, the coatings were not polished to anything close to a mirror finish. Yeah, they were polished, and the surface was relatively smooth (like factory paint on a car-- there was some degree of orange peel, but the overall feel was slick). But the color was still pretty gray. I've seen these coatings polished to look almost like chrome, but figured that was simply a cosmetic step. Are you saying that polishing adds significant longevity? If so, that may answer a lot of questions.

Edit: both of the headers JetHot coated for me in the late '90s looked more like your second pic than your first one, to give you an idea of how they were returned to me. And the failure of the coating on my BMW header and resonator that I attributed to water splashing on the hot surface looked very much like your third pic, except that it was confined mostly to the very bottom of the pipes that would have gotten splashed in the rain. There's was also evidence of staining by dirty water, which is why I assumed the rust spots were due to water (the car was an occasional derived, and thus saw rain at times).

Since you clearly have a great deal of experience in this area, what is your honest assessment of the thermal insulating properties of the various coatings? Seems to me that it is effective to a degree, although not quite as much so as the coaters would have us believe. The parts do seem to cool down quicker.

I too am interested in your recommendation for sources for the most effective exhaust coatings, either here or by PM, if forum rules preclude public recommendations.

Oh, and thanks to the OP for the thread. As you say, lots of good discussion here. And kudos to Joe and Fabspeed for being up front and looking for a solution. This is one of those exchanges where we all benefit, so thanks to all who are contributing.

 

I was going to ask you this question. This has been my impression with regards to coating the inner primary tubes. I would think it would be very difficult to prep the inner tubes and then get the coating to be applied evenly throughout the tubes. Then verification of how well the coating is holding up with use.

 

I am interested in a response from CoatThis on the thermal insulating properties of the various coatings as well.

 

When my coating was done I asked this question as well and was told the coater drags a wand through the tubes. I looked in the tubes with a pin cam and the coating appeared consistent.....

 

You can NOT wrap this type of ceramic or you will over-heat it again. If you plan to wrap an exhaust you will definitely need a high temp ceramic rated at 2000F+

 

Hmmm, most “effective” is a bit loaded. There are several types types of coatings and they all have pro’s and con’s. It really comes down to the application and your specific expectations.

The bright ceramic coating we’ve been discussing is actually a very functional ceramic thermal barrier but it has temperature limitations that affect it both aesthetically and functionally as we’ve seen firsthand. Within its operating range it works great.

For applications outside of the temp range of normal bright ceramic I’d recommend a high temp ceramic which is typically rated at 1700F – 2000F+. These are typically the first choice coating for any supercharged or turbocharged applications or any others that run outside of the norm in in timing or fuel parameters.

Plasma spray falls somewhere in between. It’s a pretty good thermal barrier, but you can only coat the ID of components, aesthetically it looks pretty poor, it can soak up gas / oils and it’s not the best option for corrosion resistance.