Is RTV Silicone corrosive to painted metal?

[Jackphom]

Recently my 2017 VW GTI started leaking through the rear speaker, apparently it is a problem with the MK7 platforms due to the seal behind the speaker deteriorating over time. It is a CPO but I rather just fix it myself than take it to the dealer.

Basically the speaker has a rubber/foam gasket that forms a seal with the door. I wanted to know if I could use any RTV silicone sealant or would that be corrosive to the metal over time? I heard some sealants are acidic and could eat at the painted galvanized steel.

 

[doitmyself]

When I contacted a Permatex person some years ago for advice on a RTV in a non-automotive application (galvanized vent), he recommended their Ultra Black as one of their better/best RTV's for non-corrosion, adhesion, oil resistance, etc.. A peek at their product data sheet will support this.

Permatex® Ultra Black® Maximum Oil Resistance RTV Silicone Gasket...

OEM specified. For dealership warranty requirements, Ultra Black® ensures extended drivetrain warranty compliance. Fast-curing formula. Sensor-safe, low odor, noncorrosive. Meets performance specs of OE silicone gaskets. Retains high flexibility, oil resistant properties through use of a...

www.permatex.com

 

[kschachn]

Yes most RTV sold most places is an acetic acid cure. You can find alcohol cure RTV however, those are sometimes labeled as potting compounds. I bought Dow Corning 838(?) once from McMaster-Carr to seal up a trailer wiring connection.

Once the RTV has cured though you should be okay.

 

[Jackphom]

Yes most RTV sold most places is an acetic acid cure. You can find alcohol cure RTV however, those are sometimes labeled as potting compounds. I bought Dow Corning 838(?) once from McMaster-Carr to seal up a trailer wiring connection.

Once the RTV has cured though you should be okay.

How about Permatex Ultra Blue?
I've looked the TDS report on Permatex's website and it doesn't list Acetic, also states that it's non-corrosive. Should I just go with a neutral silicone instead?

 

[kschachn]

Sounds like it should be fine. Or that Ultra Black as doitmyself mentioned.

 

[Jackphom]

Thanks, all!

 

[vavavroom]

The corrosion issues are with yellow metals, solder, zinc and galvanized steel. There are neutral cure silicones that do not release corrosive acetic acid, for example, Dow Corning 737. It's heat-resistant to 350F.

 

[BlueOvalFitter]

Yes most RTV sold most places is an acetic acid cure. You can find alcohol cure RTV however, those are sometimes labeled as potting compounds. I bought Dow Corning 838(?) once from McMaster-Carr to seal up a trailer wiring connection.

Once the RTV has cured though you should be okay.

I once used some Gorilla brand clear silicone on a female friends gasket of the 3rd brake light. I didn't go crazy with it. I just applied a dab and smeared it on the gasket. A few months later I noticed 1 of the bulbs wasn't working. When I removed the light the paint came off with it in a few spots.

 

[Jackphom]

I'm just gonna go ahead and order netural cure silicone

 

[Doc8404]

I use Ultra Black for everything

 

[Dave9]

Any automotive RTV spec'd as "Sensor Safe" is not acid cure so will be fine, including Permatex ultra blue.

 

[ripcord]

Any automotive RTV spec'd as "Sensor Safe" is not acid cure so will be fine, including Permatex ultra blue.

That's good info. Thanks!