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Recently had the exhaust manifolds off my 63/250hp. Sandblasted them, wiped them down with acetone on a rag, waited a day and applied P15 with a brush. Waited 2 days and brushed on another coat. 2 weeks later installed on engine and began to drive car occasionally. Now, a month later and approx 250 miles on the engine the P15 has begun to "flake" in places. Trying to determine what went wrong during the installation of the P15 or is it the product? I had P15 on those manifolds for over 20 years previously and I hadn't had anything like that occur. Any suggestions on what can be done to stop the flaking without pulling the manifolds? . Thanks-lib
They supply a cleaner / degreaser specific to this high temperature paint. The other gotcha is never brush directly from the can but go from a small cup to the bush. Finally, did you do the 15 minute cure before shutting down?
My experience is that if you follow the Yellow Brick Road that stuff sticks very well for a long time.
Is the second coat flaking off the first or is the first coat flaking off the manifold. As Nowhere Man says, you may have waited too long between coats. You have to apply the second coat before the first has fully cured, otherwise it won't stick. I assume you used high heat paint.
Lib - Not sure what happened to your exhaust manifolds. I used POR15 on my 65 396 exhaust manifolds about the way you did yours. I wire brushed them, flushed them off with Brake Clean, let them dry overnight and then brushed
their Gray Ex Manifold paint on with just a 1-inch chip brush. Let that cure for 24 hours and applied a second coat. Their instructions say the second coat can be applied in 24 hours, not any mention of too much time for curing other than to say
it cures to the touch in 4 hours so you'd guess that in 24 hours, it's fairly well cured overall and no longer tacky. After the second coat had a day to dry, I put them into the oven at 300 degrees for about an hour including cool down and I have about 700 miles on them since then and they look very good...if I do say so myself. And as to the curing, I used the oven but yours got cured when you fired it up, although there might be some difference since on a running engine, I'd guess the manifolds would
see temps more like 450+ than 300. First pic as cleaned, ready for POR15, second pic after the second coat and over cure of 300* for roughly an hour. Last pic just taken with maybe 700 or so miles on the engine/manifolds.
I used Por 15 high temp spray paint 10+ years and many 1000's of miles ago. Still looks nice. Sand blast your manifolds to remove paint. Spray on one heavy coat, let dry. Then cure in your oven at 400F for 2 hours ( when your wife is not home ) as per instructions on the tin. Still looks good.
I had mine done with POR 15 25 years ago and they look as good today as they did back then. I know the person that did mine baked them in an oven, which was in his shop and not his wife’s kitchen, for some amount of time. Don’t remember the temp or time in the oven.
Recently had the exhaust manifolds off my 63/250hp. Sandblasted them, wiped them down with acetone on a rag, waited a day and applied P15 with a brush. Waited 2 days and brushed on another coat. 2 weeks later installed on engine and began to drive car occasionally. Now, a month later and approx 250 miles on the engine the P15 has begun to "flake" in places. Trying to determine what went wrong during the installation of the P15 or is it the product? I had P15 on those manifolds for over 20 years previously and I hadn't had anything like that occur. Any suggestions on what can be done to stop the flaking without pulling the manifolds? . Thanks-lib
I had the same issue. Followed all instructions to a tee and one manifold started to flake just like yours, other looked perfect. I reached out to Por15 and they told me to brush off flaking and re-clean with a dish soap solution and reapply the manifold paint. I did this without removing the manifold and reapplied two coats with an acid brush. No problems since!
Sonny boy, lemme tellya what we had to do back when the world was still in black and white. We didn't have no pour fifteen or pore 15 or what ever you young whippersnappers call it now. Nosir. What we had was copper paint. You, over there, stop laughing. I'm trying to be serious here and to teach you sumpthin. Now pay 'tention!!!
We learnt that if ya sprayed copper paint on yur zhaust manyfolds that it wud turn a nice metallic gray colour once ya got the engine guddin hot. Even better, if ya sandy blasted yur manyfolds first and cleaned'rm up real gud like, the copper paint would stick fer a long long time.
Hear is a manyfold I painted wit coppery paint back in '79. It ain't grate now, but cut me some slak. This paint is 47(!) years old. Will ur pore fiftean look this un-bad in forty seven years???
POR 15 on stock exhaust manifold?
Looks great!