Quick Question - Whats This For?

[welscher08]

On my 2003 Silverado on the rear cab corners just, there is a tiny pin sized hole in the bottom of the cab corners. What is this for? To let air/moisture in there to prevent rust? Main reason i am curious is i am thinking of undercoating down there so rocks/gravel don't chip the paint away.

 

Also in my rear fender wells there are these 3 round plastic circles/seals in each fender well. What are those for also?

 

I will take pictures tomorrow and post them. Thanks! Ryan

[085300]

So you bed doesnt fill up with water?

[mipsco1]

i think i might have to wait for pics because i cant figuer out what seals your talking about

[welscher08]

Well here are the pics, i just went up and took some. Let me know if you think covering up the small holes in the cab corners would be good/bad and then what your think those black 'seals' seem to be. Ryan

[Chads09Sierra]

Well here are the pics, i just went up and took some. Let me know if you think covering up the small holes in the cab corners would be good/bad and then what your think those black 'seals' seem to be. Ryan

 

 

Remove those black seals and squirt some oil in those oils before you undercoat over them. it will help quit it from rusting from the inside out.

[welscher08]

Yeah i was not going to undercoat over them just in case, i just didn't know what exactly they would be for. But you think remove them and oil them up and let me go?

[Chads09Sierra]

i dont know what they are exactly for, but my grandfather always told me that they were there to allow you to oil the places that rust first. he would always go around and pull all those plugs out and spray some motor oil in the holes and then drive down a dry dusty road. the dirt will stick to the oil and it will build up a nice undercoat. you have to do it a couple times a year though to build a nice base. but to answer the original question, im not sure what they are, but maybe someone will chime in with what they really are.

[welscher08]

Yeah I hope they do as i am curious to what they actually are and then also anyone wanna share their ideas on the rear cab corners and the pinsized hole? Do i dare undercoat over it or leave it be

[mipsco1]

from my understanding those plugs are for that exact reason to prevent crap getting in there and rusting. my grandpas 98 has them and he always pull them out in the spring and fills them with grease, just looked at my 04 and i do not have them. as for the cab corners i have no clue

[C. Charles Hahn]

I may be wrong but the way that cab corner looks it's ALMOST like it was repaired with a patch panel or something.... so maybe it was damaged and repaired with a piece that left a gap?

[mipsco1]

yeah it kinds of looks like a skip weld but its hard to tell from the pic

[welscher08]

Thats weird your 04 doesn't have them?! My 03 2500HD work truck has them, and our new 09 2500HD has them as well, and even one higher up in the fender well as well. But if thats what they are for i will tape over them and spray around them, and when i put my black textured fender flares on see if it covers them up or not and clean them out before i put them on for good.

 

Yeah i think both sides of my truck has that hole in the cab corner. It could have been repaired maybe, but it has 35,000 miles on it and was a one owner and i bought it private...but still ya never know. Thanks for all the help guys!

[Spurshot]

I'm guessing they are there for some manufacturing purpose like tooling alignment, etc., and not for squirting oil into. Otherwise there would be a maintenance task to squirt oil in them at some interval. I've never heard of such a task, but that doesn't mean it doesn't exist.

 

These newer truck have galvanized bodies and shouldn't rust anywhere near as bad as old models prior to galvanizing being introduced.

[welscher08]

Thanks for all the help everyone! I just pulled those rubber 'seals' out of the fender wells to get ready to undercoat. You can reach up and get to them to from in front of the fender wells to.

 

And i check both sides of the truck have the little hole in the cab corners so i think it must just be for alignment like you say...so i am gonna go ahead and undercoat them. Thanks for everything guys, i will have to post pics when i get everything done and all the accessories i bought for it on there and then when i get it all waxed up, its a process a long one too it seems. Ryan

[C. Charles Hahn]

I'm guessing they are there for some manufacturing purpose like tooling alignment, etc., and not for squirting oil into. Otherwise there would be a maintenance task to squirt oil in them at some interval. I've never heard of such a task, but that doesn't mean it doesn't exist.

 

These newer truck have galvanized bodies and shouldn't rust anywhere near as bad as old models prior to galvanizing being introduced.

 

Yeah the first thing on the GMT900s to rust will be the frames.... they're just waxed/cosmolined, not painted or powder coated!