How to fix GM undercoating and frame rust with POR15

The.Sundae.Drive · July 4, 2019

The number 1 complaint (although it is a very tight race with the AFM and condenser issues) I have with my truck is the worthless undercoating that General Motors puts on their Chevy and GMC trucks. It is a wax based undercoating that quickly hardens and flakes off of the frame. You can look under brand new Silverados and Sierras sitting on dealer lots and already see rust starting to form where the wax did not adhere well. This is particularly frustrating for vehicles, such as mine, that call the rust belt home. It has received enough notice and generated a similar quantity of complaints, that GM has, in some cases, re-coated the frames of particularly badly rusting trucks. Unfortunately, they simply use the exact same wax material and rarely prepare the service correctly by removing the rust and old wax. Since the wax does a poor job of bonding and air-locking the already formed rust, this only masks the problem for it to return worse a few months later. In this video, we show you how to fix this problem correctly so that you will have a rust free frame for many years to come.

Nanotech Environmental · July 4, 2019

I had an asphalt based coating put on my truck when new. It stays pretty flexible and seals well. However, where something contacts the frame, such as hoist pads, or a stray rock etc., the coating can get damaged or removed & rust can start. I go over it every spring and do touchups with a wire wheel and recoat with the same product. A lot less work than stripping all the rust & wax & recoating. Granted, if the frame is already like the one in the vid, the process outlined is correct.
My last truck had heavy frame rust. I want to avoid that on this one.
I'd really like a truck with a stainless chassis & lower cab panels(floor, corners, rockers etc.). I'd pay extra for it.

Edited July 4, 2019 by Nanotech Environmental

carkhz316 · July 4, 2019

I really want to like this, because POR15 is good in some instances, but slathering the frame in a hardening top-coating just never seems to work that well. While it's not POR15, its still relevant below:

Rock1500 · July 5, 2019

4 hours ago, carkhz316 said:

I really want to like this, because POR15 is good in some instances, but slathering the frame in a hardening top-coating just never seems to work that well. While it's not POR15, its still relevant below:

So what is the better solution?

davester · July 5, 2019

I can tell you that coating the frame with bedliner is a bad idea. Guy I bought a trailer from did the trailer with some thick rubberized stuff, and while most of it was ok (well bonded to the frame), there were numerous cuts in it down to the metal, and anywhere there was a cut, the stuff would hold water inside and rust the hell out of that spot. And it sucks to get off, as even high-strength paint remover just runs off. I've been slowly getting it off either using an air chisel to peel it off for open areas or an angle grinder with a wire wheel (or a cup) in tighter spots.

[email protected] · July 5, 2019

Why can't the auto manufacturers just do it right when they have 100% access to the frame. There's got to be a material that they can dump it in put it in a trough spray it or something that would eliminate the rusting of the frame. This seems to be such a normal amount of work and since I'm OCD I know you can never get all of the frame so why bother.

davester · July 5, 2019

Because there is nothing that will "eliminate the rusting of the frame". There's only a "applying X for this much money, most frames will have this much rust after this much time". In general, what GM does works pretty good, but for some vehicles, due to a variety of circumstances (applied slightly wrong, washed off, extra salt on the roads where it is driven), it doesn't work as well and the frame rusts prematurely.

carkhz316 · July 11, 2019

On 7/4/2019 at 9:19 PM, Rock1500 said:

So what is the better solution?

Well, like Eric in the video suggests, Fluid Film or equivalent is going to be a better option than any hardened or rubberized coating. Davester above though is correct in that whatever you do is pretty much just staving off the inevitable, unfortunately. I'm currently trying Fluid Film to see how it performs. The only caveat to it is that it stays "wet", and as such, it tends to get washed off over time, and has to be reapplied periodically (typically once a year for best results).

300 Blackout · July 12, 2019

So what is the better solution?

My original frame had insane amounts of rust. I did tons of prep and sprayed POR-15 and top coated with an asphalt based coating. 4 months later my frame was totaled in a crash. I loathed the frame wax so I fronted the coin to take the new frame to get powder coated before it was installed. Then I sprayed the inside of the frame with 3 cans of Eastwood’s internal frame coating (a phenomenal product and an absolute b*ch to remove). I might still spray the inside of it with fluid film annually, haven’t decided yet.

If you can accept the frame will never be free of rust, then just touch it up with more of the original wax coating from Daubert, spray fluid film or both. As long as you keep up on it, rinse it off occasionally (don’t power wash it) and don’t ignore it, it won’t be a big problem.

When the frame wax dries out is when water has a chance to get behind it and create big issues. If this happens, you will notice the frame wax looks like a sheet and can be peeled. Fluid film will help maintain the wax’s ability to flow, but it also makes it more able to be wiped off. Again, it’s something that will have to be maintained and touched up as needed.

The.Sundae.Drive · July 15, 2019

On 7/4/2019 at 4:28 PM, Nanotech Environmental said:

I had an asphalt based coating put on my truck when new. It stays pretty flexible and seals well. However, where something contacts the frame, such as hoist pads, or a stray rock etc., the coating can get damaged or removed & rust can start. I go over it every spring and do touchups with a wire wheel and recoat with the same product. A lot less work than stripping all the rust & wax & recoating. Granted, if the frame is already like the one in the vid, the process outlined is correct.
My last truck had heavy frame rust. I want to avoid that on this one.
I'd really like a truck with a stainless chassis & lower cab panels(floor, corners, rockers etc.). I'd pay extra for it.

Same. I think a lot of guys (including myself) would pay extra for more corrosion resistant materials and better coatings from the factory. Call it the Northern Edition or something. I'll gladly pay lol

The.Sundae.Drive · July 15, 2019

On 7/4/2019 at 6:05 PM, carkhz316 said:

I really want to like this, because POR15 is good in some instances, but slathering the frame in a hardening top-coating just never seems to work that well. While it's not POR15, its still relevant below:

I'll check the video out for sure. There probably isn't an ideal solution. I'll need to do some research on how POR15 and fluid film react but assuming they play nice, I'll probably hit the frame with some each fall to hopefully keep what I've done so far intact.

The.Sundae.Drive · July 15, 2019

On 7/5/2019 at 3:01 AM, davester said:

I can tell you that coating the frame with bedliner is a bad idea. Guy I bought a trailer from did the trailer with some thick rubberized stuff, and while most of it was ok (well bonded to the frame), there were numerous cuts in it down to the metal, and anywhere there was a cut, the stuff would hold water inside and rust the hell out of that spot. And it sucks to get off, as even high-strength paint remover just runs off. I've been slowly getting it off either using an air chisel to peel it off for open areas or an angle grinder with a wire wheel (or a cup) in tighter spots.

Good point about bed liner, POR15 isn't a bed liner but probably will still hold moisture if compromised. I definitely am curious to see how the frame holds up with the application I've put on. I'll be looking to add some fluid film or something each each year to help.

The.Sundae.Drive · July 15, 2019

On 7/11/2019 at 8:41 PM, 300 Blackout said:

My original frame had insane amounts of rust. I did tons of prep and sprayed POR-15 and top coated with an asphalt based coating. 4 months later my frame was totaled in a crash. I loathed the frame wax so I fronted the coin to take the new frame to get powder coated before it was installed. Then I sprayed the inside of the frame with 3 cans of Eastwood’s internal frame coating (a phenomenal product and an absolute b*ch to remove). I might still spray the inside of it with fluid film annually, haven’t decided yet.

If you can accept the frame will never be free of rust, then just touch it up with more of the original wax coating from Daubert, spray fluid film or both. As long as you keep up on it, rinse it off occasionally (don’t power wash it) and don’t ignore it, it won’t be a big problem.

When the frame wax dries out is when water has a chance to get behind it and create big issues. If this happens, you will notice the frame wax looks like a sheet and can be peeled. Fluid film will help maintain the wax’s ability to flow, but it also makes it more able to be wiped off. Again, it’s something that will have to be maintained and touched up as needed.

Good points and definitely plan to keep touching it up with POR15 if I see any rust and I'm going to go over everything with fluid film (after I find out if por15 and fluid film play well together). Wonder how much a stainless steel frame would cost lol

300 Blackout · July 15, 2019

Good points and definitely plan to keep touching it up with POR15 if I see any rust and I'm going to go over everything with fluid film (after I find out if por15 and fluid film play well together). Wonder how much a stainless steel frame would cost lol

Check out this thread. This is what my frame looked like and the original reason I joined the forum. Substantial Frame Rust 2014 Sierra
https://r.tapatalk.com/shareLink?share_fid=33003&share_tid=205505&share_pid=2039596&url=https%3A%2F%2Fwww%2Egm-trucks%2Ecom%2Fforums%2Findex%2Ephp%3F%2Ftopic%2F205505-Substantial-Frame-Rust-2014-Sierra%2Fpage__view__findpost__p__2039596&share_type=t
I’ve posted a bunch of pictures along with the process I followed to prep the frame in other threads. The short version is needle scaler, angle grinder wire wheel, xylene to dissolve the wax, POR15 Metal Prep with zinc, sprayed POR15, top coated with Rust-Oleum Rubberized undercoating. Basically, we followed similar methods although I didn’t remove my bed to do it.

I hope the POR15 works for a long time for you. Unfortunately, after my frame was damaged in the crash, I was really disappointed by my observations. There’s no doubt the coating is very tough. My concern is the claimed bonding to the pores of the rusted metal vs my observations after the crash.

Here is a picture of my frame where it bent after being rear ended. You can clearly see the rusted metal beneath the area where the POR15 ripped. According to their claims, the coating should have been bonded to this underlying rust. If the coating was bonded to the rust, my expectation is that it should have flexed with the frame rather than tear and detach from the metal. I spent a long time prepping my frame. The day that I sprayed was ideal conditions. I also thinned the coating with their thinner. If anything, the coating should have flowed further into the rust pores since it was less viscous than the virgin product.

It’s anyone’s guess whether or not this is an indication that moisture could seep under the POR15 coating and cause additional rust, hidden from view. Too many variables exist from one persons application to another to really be able to blame the product, rather than the prep.

In my anecdotal observations, when I had a drip of POR15 on a surface that needed to be removed (drive shaft, control arm, etc..) I got my fingernail under the edge and was able to peel it off like a piece of tape. When I had Eastwood’s Internal Frame Coating drips that needed to be removed, my fingernail was chewed up by the time I got a single millimeter of the drip scraped off.

POR15 and Fluid Film are fine together. If I can find the reference I used to confirm this when I was looking into it, I’ll post in this thread. Good luck!

The.Sundae.Drive · July 17, 2019

On 7/15/2019 at 2:38 AM, 300 Blackout said:

Check out this thread. This is what my frame looked like and the original reason I joined the forum. Substantial Frame Rust 2014 Sierra
https://r.tapatalk.com/shareLink?share_fid=33003&share_tid=205505&share_pid=2039596&url=https%3A%2F%2Fwww%2Egm-trucks%2Ecom%2Fforums%2Findex%2Ephp%3F%2Ftopic%2F205505-Substantial-Frame-Rust-2014-Sierra%2Fpage__view__findpost__p__2039596&share_type=t
I’ve posted a bunch of pictures along with the process I followed to prep the frame in other threads. The short version is needle scaler, angle grinder wire wheel, xylene to dissolve the wax, POR15 Metal Prep with zinc, sprayed POR15, top coated with Rust-Oleum Rubberized undercoating. Basically, we followed similar methods although I didn’t remove my bed to do it.

I hope the POR15 works for a long time for you. Unfortunately, after my frame was damaged in the crash, I was really disappointed by my observations. There’s no doubt the coating is very tough. My concern is the claimed bonding to the pores of the rusted metal vs my observations after the crash.

Here is a picture of my frame where it bent after being rear ended. You can clearly see the rusted metal beneath the area where the POR15 ripped. According to their claims, the coating should have been bonded to this underlying rust. If the coating was bonded to the rust, my expectation is that it should have flexed with the frame rather than tear and detach from the metal. I spent a long time prepping my frame. The day that I sprayed was ideal conditions. I also thinned the coating with their thinner. If anything, the coating should have flowed further into the rust pores since it was less viscous than the virgin product.

It’s anyone’s guess whether or not this is an indication that moisture could seep under the POR15 coating and cause additional rust, hidden from view. Too many variables exist from one persons application to another to really be able to blame the product, rather than the prep.

In my anecdotal observations, when I had a drip of POR15 on a surface that needed to be removed (drive shaft, control arm, etc..) I got my fingernail under the edge and was able to peel it off like a piece of tape. When I had Eastwood’s Internal Frame Coating drips that needed to be removed, my fingernail was chewed up by the time I got a single millimeter of the drip scraped off.

POR15 and Fluid Film are fine together. If I can find the reference I used to confirm this when I was looking into it, I’ll post in this thread. Good luck!

Thanks for all of the info! I will definitely check that link out. This is why the forums are so much better than Facebook groups ?? good to know that fluid film will play with it. I still have to do the front half of my frame, maybe I should use Eastwood on everything??