Metal Gasket Coating is Bubbling?

[The Critic]

2019 Honda Pilot with 75K.

Front Water Passage Gasket. Disassembled and found the black coating to be gone from one side and bubbling on the other.

Rear gasket is in perfect condition.

What do you think caused this?

 

[TCL]

Heat.
I wouldn't worry about it.

 

[PontiacHO]

This would give some reassurance that your reassembled job is sealed.

 

[iCurious]

Was this near the EGR valve?

 

[Nukeman7]

I had to perform the exact same repair on a 2006 Honda Odyssey last year and found the metal gasket coating to be delaminated and bubbling just like your photos. I decided to try the redesigned FelPro ES72774 gasket which has a thin molded bead of red silicone surrounding the water passage orifices. I figured that it was an upgrade over just the black (Teflon) type coating on the OEM gasket. Fingers crossed that it will last 18 more years!

 

[KrisZ]

I wonder what happened in this area. Looks like someone was in there and perhaps they used an aggressive degreaser or some other cleaner which would’ve wicked its way into the gasket.

 

[Nukeman7]

I wonder what happened in this area. Looks like someone was in there and perhaps they used an aggressive degreaser or some other cleaner which would’ve wicked its way into the gasket.

No, that is the dried residue from the Honda blue/green coolant that seeped out from the delaminated gasket. It is the first sign that the gasket's integrity has been compromised.

 

[KrisZ]

No, that is the dried residue from the Honda blue/green coolant that seeped out from the delaminated gasket. It is the first sign that the gasket's integrity has been compromised.

Got it. Could that have been the cause of bubbling/delamination then?

 

[Nukeman7]

Got it. Could that have been the cause of bubbling/delamination then?

I don't believe so. If you look at photo, the coolant residue only appears underneath the left side of the metal gasket. Whereas the delamination and bubbling of the black coating is apparent on the upper portion of the gasket on the right side where no evidence of coolant leakage is present.

Just like @The Critic's J35, my leak was at the exact same location from the small coolant port passage on the left side. The large middle port area is clean, so I doubt the leak was emanating from that location.