Undercarriage

tinbad · May 10, 2020

I thought I hit something driving today and decided to check underneath (for the first time.. I know..). Two things got me concerned:

1. There’s seems to be some “bubbling” on the part of the frame(?) could it be they screwed up and painted/coated while moist? Or is this normal?

2. I noted a very distinct checker pattern of rust on 4 corners of the frame (Showing pic of 1 but they’re on all 4 sides in the same location). Looks like something scratched/imprinted from a lift(?)

Should I be worried? Needless to say all I’ve done is take it to the dealer for the numerous issues I’ve been having so if anyone is at fault it would be them (or the factory).

19 LT TB, 13k miles, only had the truck for 10 months (custom ordered and delivered in July 2019)...

OnTheReel · May 10, 2020

Normal. Frames are dipped, so you’ll see some excess runs and bubbles where it collects. Mine has that stuff in the same spot, so did my 2016.

Since it’s just a wax coating, it very easily rubs off of the lift points. I touch mine up with the same product the factory used after service, not a big deal if you keep up with it.

https://www.daubertchemical.com/store/product-list/corrosion-prevention/nox-rust-x-121b

Z71-Like-A-Cadillac · May 11, 2020

2 hours ago, OnTheReel said:

Normal. Frames are dipped, so you’ll see some excess runs and bubbles where it collects. Mine has that stuff in the same spot, so did my 2016.

Since it’s just a wax coating, it very easily rubs off of the lift points. I touch mine up with the same product the factory used after service, not a big deal if you keep up with it.

https://www.daubertchemical.com/store/product-list/corrosion-prevention/nox-rust-x-121b

How far does a can of that stuff go? I think I'm going to get some. Just trying to decide how much I should buy.

OnTheReel · May 11, 2020

10 minutes ago, the-wild-moose said:

How far does a can of that stuff go? I think I'm going to get some. Just trying to decide how much I should buy.

It goes a long way for just touching up. I did buy a case because the price break was so big. Split it with a few buddies and still have 2 of the 3 cans I started with like 4 years ago.

tinbad · May 11, 2020

That’s a relief, thanks. This truck hasn’t been trouble free to say the least and glad I don’t have to add this to list.

So just spray the stuff on the rusty parts? I’m also not sure how much of it to get, a can is 15$ but then shipping is too so was thinking to get a case but I likely won’t use it all.

bdsilverado · May 11, 2020

Is that lift mark even in the correct spot to lift the trucks up from?

OnTheReel · May 11, 2020

54 minutes ago, tinbad said:

So just spray the stuff on the rusty parts? I’m also not sure how much of it to get, a can is 15$ but then shipping is too so was thinking to get a case but I likely won’t use it all.

Yes, it can be applied directly to active rust. The company claims it’s very effective at stopping further corrosion, and that’s been my experience. The weakness is anywhere lift pads touch and edges of body mounts where the coating would naturally be thin. I do my best to keep up with those areas here in the rust belt and everything under my truck still looks more or less like new after two winters.

A case is literally a lifetime supply and then some.

2016 Sierra Owner · May 11, 2020

15 hours ago, bdsilverado said:

Is that lift mark even in the correct spot to lift the trucks up from?

I would say yes. Because the just past the hole in the frame on the far right of the pic. The frame starts to curve upward and the spot circled by the OP is the closest flat spot there is to the front.

gemarsh · February 11, 2023

Just can't have good things, nowadays.

micew64352 · April 6, 2023

Hello! Based on what you’ve described and the picture you’ve attached, it seems like the bubbling and rust on the frame are not normal occurrences. It’s understandable that you’re concerned, especially since you’ve only had the truck for 10 months and have driven it for only 13k miles.

Since you’ve mentioned that you’ve only taken the truck to the dealer for numerous issues, it’s possible that the fault could be on them or the factory. It’s best to bring your truck to the dealer as soon as possible so they can properly inspect and address the issues.

Edited April 7, 2023 by txab

redwngr · April 7, 2023

On 4/6/2023 at 4:04 AM, micew64352 said:

Hello! Based on what you’ve described and the picture you’ve attached, it seems like the bubbling and rust on the frame are not normal occurrences. It’s understandable that you’re concerned, especially since you’ve only had the truck for 10 months and have driven it for only 13k miles.

Since you’ve mentioned that you’ve only taken the truck to the dealer for numerous issues, it’s possible that the fault could be on them or the factory. It’s best to bring your truck to the dealer as soon as possible so they can properly inspect and address the issues.

OP's second picture -- the one that was called 'bubbling' is absolutely normal.

Frames are hung by the front end and washed then dipped in a tank containing the waxy frame coating.

Those 'bubbles' are thicker coating that didn't run/drain/drip off.

That part of the crossmember would have been the 'bottom side' of the crossmember when it came out of the dip tank.

Gangly · April 7, 2023

That's not bubbling, those are droplets where excess coating material has collected without dripping off. If you see that, you know you have sufficient coating there, its a good thing to see. The marks on your frame are from lift pads on a vehicle lift. Your vehicle got put on a lift and that's where the lift forks contacted the frame, completely normal to see surface rust here. if you are nervous, purchase a few cans of Daubert Nox, it's expensive but it's what the manufacturer uses as a coating at the factory. I have used it multiple times as touchup and it works VERY well.

Edited April 7, 2023 by Gangly

Interleukin6 · April 8, 2023

Before applying Daubert Nox, should I sand down surface rust or can it be used on top of rust?

NE18 · April 10, 2023

I always sand down IL6. Then I’ll use a rust inhibitor spray paint then the wax.

Gangly · April 11, 2023

On 4/8/2023 at 11:25 AM, Interleukin6 said:

Before applying Daubert Nox, should I sand down surface rust or can it be used on top of rust?

I never sand down the surface because I don't want to go through any coatings/protectants on the metal surface. If rust is present, I wipe the area clean of the coating, apply a rust remover/dissolver, let it sit then rinse it off, dry it, apply a layer of protective paint, then spray the Daubert coating. If there is no rust or just very minor surface rust, I wipe the surface rust off to get it as clean as possible, and spray the Daubert NOx directly onto the surface and move on.