Tank cover removal

[mkinney716]

I have two steel tanks on a steel boat. I’m trying to remove cover on first tank so I can clean out tank and install a fuel level sensor. It is attached by 45 screws and silicone sealant. I have removed all fasteners but the silicone won’t release. I’ve tries a razor knife as well as a screwdriver. I can’t get the cover loose enough to insert the screwdriver and can’t get a good angle to use the razor knife. Any suggestions will be greatly appreciated. The silicone was applied about 25 years ago.

[gonesail]

if all else fails you can install an inspection port in the cover. hopefully it won't come to that.

[coopec43]

Would a multi tool cut the silicone sealant?

https://www.google.com/search?source...a8gCCsQ4dUDCAw

[tkeithlu]

I'm going to assume that these tanks hold diesel. Diesel doesn't produce flammable gas until about 150 degrees F., so:

It may be time to move to heat. An ordinary propane torch applied locally along the silicone line should char/soften it enough for it to release. Be careful, and keep a hose handy to cool everything down in a hurry if needed.

[Orion Jim]

I agree that heat would help but I’d use a heat gun, not an open flame.

[tkeithlu]

Good point, Orion Jim. A heat gun should be enough heat to at least soften it so a thin blade could get between the lid and the tank.

[sailormed]

You can try Anti Bond, works for me for difficult unknown sealant. Spray on and do something else, it is a chemical reaction and needs time for penetration. Come back after half an hour, try and repeat if necessary.