Exhaust valve strange substance

[EVR]

Having my left side valve changed in July 2019 since the rod was broken, I checked on it today, to find it covered in a strange substance:







Do you have any idea what this could be? The valve seems to operate correctly, you can hear them open at the intended RPM (or with the CC Charger Remote) and I tried to push this one manually, it seems fine.

I might have driven on salted roads last winter, but still. It does not look like corrosion. The valve was a brand new one bought directly from AM supplier, Helical. I did not checked the right one, but if I recall it correctly, it's mounted in a slightly less visible location.

It surely wasn't like this when the exhaust shop did the job:



Thanks!

Edited by EVR on Sunday 4th October 12:04

[pschlute]

Could it be residue from a substance sprayed on the joint to check for gas leakage after fitting ?

[bullet7]

Looks similar to the substance that AM spray onto the disc hubs at service to prevent corrosion.

[EVR]

pschlute said:

Could it be residue from a substance sprayed on the joint to check for gas leakage after fitting ?

I don't remember the muffler shop doing it.

It could have been beneficial, but I sprayed some butterfly valve cleaner and it disappeared.

I am chatting via Whatsapp with Misterblu, he noticed the same kind of substance on his manifolds. He is thinking that AM Milano (we both serviced our cars there) could have sprayed it as bullet said, to prevent corrosion. It could be zinc spray coating, maybe?