Seam Sealer

[rboltz]

Should the seam where the uper sheet metal fenders attach to the heavy curved lower fenders be sealed? Aren't they welded together? Looks like there was something in there at one time.

[sf38a1]

I used a paintable silicon caulk that i got at Home Depot.I have used it B4 on the ambulance to seal the gutters and it has worked well for 3 years.I think it was around 2.75 a tube.make sure its paintable or it will become a pain in the #$$ to fix it. I guess you could use seam sealer,but Its a lot more , and I have a problem getting to the auto body store that sells it.

[randyscycle]

Any silicone caulk or sealer shouldn't be used on unpainted steel. It does cause rust. Seam sealer is best, as it is designed for that purpose and it also is flexible enough for bodywork. Silicone tends to shrink after a while and pull away from the seams.

[sf38a1]

I prime first then use the silicon caulk. I haven't had any problems with rust yet. Its been on the m725 for 3to 4 years, When I removed the original sealer there was rust under it. probably because it had cracked and let water get in between it and the metal.

[randyscycle]

I prime first then use the silicon caulk. I haven't had any problems with rust yet. Its been on the m725 for 3to 4 years, When I removed the original sealer there was rust under it. probably because it had cracked and let water get in between it and the metal.

I've never done it with primer first, so that probably would be OK. I know that most manufacturers and glass companies say not to use Silicone based caulks. Something about a reaction to the steel.

[rboltz]

Should that upper to lower fender gap be sealed?

[randyscycle]

Sorry, getting off topic tends to happen a lot around here......

Are you talking about the seam at the flare, or the seam where the fender meets the cowl?

Neither of those areas are sealed from the factory on any trucks I have looked at.

There was sealer between the fender mounting flange and body in the door hinge area.

[rboltz]

Where the upper fender joins the heavy flared steel. If you look at the underside (backside), there was felt in there from the factory where it bolts together. All the trucks I have seen do not appear to have anything in the exposed seam.

[randyscycle]

Actually my '67 had a rubber flap or weather seal thing in there, but no sealer. It appeared that it had never been apart until I took it apart last year, so I'd say no sealer.

Again, the only place I found any sealer was at the back row of bolts and up front where the fender tips met the core support.

[heepey]

I rewelded the flare to the upper fender on mine, there had been no sealer in that seam. there was some caulk between the fender and the wheel house and between the fender and the cowl, fender and grille panel