Smoke on high temp paint

[voucht]

Hi,

I have started my engine today. First time with the exhaust manifold I modified.

I painted this manifold and the tube with black high temperature paint (650°C).

When I ran the engine today, when it started to heat up, the manifold was smoking a lot from everywhere, a bit like if the painting was burning.

I preferred to stop rather than wait and set up a fire.

Is it normal to have smoke on the paint the first time it is used? Perhaps it is smoking a lot at the beginning, and then stabilizes after a while?

Or did I use a wrong paint, 650°C not being enough?

Thank you for your help.

[Talonmotorsport]

Did you fully clean and degrease the steel or use a primer under the high temp paint?

[voucht]

Actually, after the electrolysis, I washed it with soap, rinsed it and dried it (heat gun + pressured air from the compressor). But I did not specifically degreased with a degreasing agent (except soap )

But no primer.

The weird thing is that it was smoking (and smelling) a lot when the engine was running, but now, there is no trace of anything, no bubbles or burn paint on the parts, nothing...

But I guess by your reply that there is something wrong anyway , no?

Should I insist and let is smoke until it stops, hopping that the high temp paint wont be damaged ?

Thanks

[TSM Locost]

650 deg is not enough. gasses leaving the head is often 800 deg or more depending on the engine, most HT paints for exhausts are 1200 deg.

[voucht]

Thanks Mike,
Actually you are right, 650°C is not enough for an exhaust manifold, and it is more adapted to brakes. I couldn't find 1200°C, but I know where to get 800°C paint which seems to be the most popular one for exhaust parts.

However, I have read some forum here in Sweden about the paint I used, and it looks like this paint has to be «*cooked*» to be hardened after being applied. People put their parts in an oven, ore use a heat gun. Some other say that running the engine for exhaust parts and letting it cool down id the way to go, and will do the hardening job.

That is what I did yesterday. After 10-15 minutes of running the engine, the manifold stopped smoking, and the paint still look nice and hasn't been affected by the heat.

I'll have another run today from cold engine, and see what happen, but I think I am going to leave it like that if everything looks OK.

Thank you for the inputs.

[loony]

I remember that "few" years ago I used exhaust paint on 2T motorbike and the result was similar to yours - lot of smoke. But after first smoking ride it was OK. So should be OK with your exhaust