E350 gutter rust polyurethane vs Tripolymer vs thermoplastic

[rerod]

I drive work vehicles, so I'm not concerned about how they look. But I recently rebuilt the cummins engine in my ford E350 tow vehicle, so Iv got allot of money wrapped up in it.

My problem is that even though the undercarriage is spotless since the van is from Florida, the rain drip edge gutter has some rust from the salt air.
I will wire wheel the gutter down to bare metal, treat with rust neutralizer, fill any holes with fiberglass patch, and prime and paint with POR-15. I would then like to fill the entire gutter full of exterior caulk with UV protection instead of auto-body seam sealer so that the gutter no longer collects water. The caulk I choose needs to be removable, because the gutter will rust again as this is a temporary fix short of cutting out and welding in new metal which I cant justify.

Can anyone recommend or educate me on the best, longest lasting removable caulks on the market for my application? Iv read Geocel 2300 (Tripolymer), solarseal 900 (Terpolymer), 3M4200(polyurethane), NP1(polyurethane), Vulkem 116(polyurethane), Sika Flex (Polyurethane), Dymonic (hybrid), Kop-R-Lastic (thermoplastic) are some good choices, but making a decision is difficult with so many products.

I noticed polyurethane caulks dominate my list so I'm guessing polyurethane must last the longest? I don't want silicone because of it's "wont stick to itself" and difficult removal properties.

Thanks!

[rerod]

B.O. Plenty wrote:
Leave out the fiberglass because it absorbs water. Prime with an epoxy automotive primer then caulk it with a good 3M auto body seam sealer and paint over the top of it to seal it..Stop trying to overthink this..it will get you nowhere.

B.O.

Thanks Plenty.

The gutter has been repaired and filled before I bought the van. Unfortunately, I'm fairly certain there will be rust holes in the gutter and through the roof of the van after I remove the old body filler.

Iv read good reviews about POR-15 49033 Epoxy Putty and was going to use it to repair rust holes instead of the fiberglass patch I first mentioned. Then bondo over the 49033 Epoxy Putty.

Then your probably correct that 3M seam sealer would be better than NP1 or Vulkem 116 even though they all are Urethane/polyurethane.

[B_O__Plenty]

Leave out the fiberglass because it absorbs water. Prime with an epoxy automotive primer then caulk it with a good 3M auto body seam sealer and paint over the top of it to seal it..Stop trying to overthink this..it will get you nowhere.

B.O.