Rust Repair

[Brian71]

I noticed a hole in the left rocker this past spring when changing my winter tires.
I took it in for repairs and here is what they found.
The shop is replacing both rockers. BTW GM does7sell patch panels.
Here are some pics.
The vehicle is a 2017 Tahoe Premier
The stuff they put on the roads up here in the winter are brutal. They use a liquid brine.
I have the vehicle sprayed with oil every year

 

[BigBoyZ71]

Wow, rust the whole way down the panel? How many KMs do you have on the Tahoe?

 

[B-train]

Maybe I'm not seeing it, but the old one doesn't appear to have any oil residue on it. I have a 2017 also and have sprayed the entire truck, inside and out, with fluid film 7 years ago and the rockers are still oily when finger tested through a body plug hole - but I may want to reappky a coating based on what yiurs look like. I'll bore scope it when I get a chance and post the pics. I only have to touch up the frame rails every year or so depending on the winter. From WI, so not quite as bad as Canada, but still aggressive crap on the roads.

Not sure what you use, but fluid film or woolwax seem to be really good products that creep, grow a good fur coat, and stick around well.

 

[Brian71]

Wow, rust the whole way down the panel? How many KMs do you have on the Tahoe?

It has 230,000 km’s

 

[Brian71]

Maybe I'm not seeing it, but the old one doesn't appear to have any oil residue on it. I have a 2017 also and have sprayed the entire truck, inside and out, with fluid film 7 years ago and the rockers are still oily when finger tested through a body plug hole - but I may want to reappky a coating based on what yiurs look like. I'll bore scope it when I get a chance and post the pics. I only have to touch up the frame rails every year or so depending on the winter. From WI, so not quite as bad as Canada, but still aggressive crap on the roads.

Not sure what you use, but fluid film or woolwax seem to be really good products that creep, grow a good fur coat, and stick around well.

I get it treated every year by a company called Krown. I will ask the shop why there is little product on the panel.The rest of the vehicle is solid. I’ve noticed a lot of these and Silverado’s with rust in the same area

 

[BigBoyZ71]

I get it treated every year by a company called Krown. The rest of the vehicle is solid. I’ve noticed a lot of these and Silverado’s with rust in the same area

No hate towards Krown, but generally oil/lanolin or woolwax-based products like B-train suggested perform better than Krown's petro-based product. When I was in Ontario, I swore by "Corrosion Free" (mineral oil-based)

 

[Brian71]

No hate towards Krown, but generally oil/lanolin or woolwax-based products like B-train suggested perform better than Krown's petro-based product. When I was in Ontario, I swore by "Corrosion Free" (mineral oil-based)

I’m thinking cavity wax in that area. I am going to talk to the manager at Krown and ask why there’s little coverage on the rocker panel.
The rest of the vehicle is solid.

 

[Brian71]

Maybe I'm not seeing it, but the old one doesn't appear to have any oil residue on it. I have a 2017 also and have sprayed the entire truck, inside and out, with fluid film 7 years ago and the rockers are still oily when finger tested through a body plug hole - but I may want to reappky a coating based on what yiurs look like. I'll bore scope it when I get a chance and post the pics. I only have to touch up the frame rails every year or so depending on the winter. From WI, so not quite as bad as Canada, but still aggressive crap on the roads.

Not sure what you use, but fluid film or woolwax seem to be really good products that creep, grow a good fur coat, and stick around well.

Upon further thinking I’m going to talk with the shop owner about the lack of coverage.
I’m thinking of applying cavity wax inside the rockers

 

[GMCChevy]

Do you park in a heated garage or parking garage at all? That's the most common causes of rust like that.

I can't tell from your pics but if there was an inner rocker structure they're probably getting oil into one part of the rocker the way half of it is so clean but it's blocked from getting into the other half. I have to look at ours. I know with our older OBS one years ago one shop used the drilled holes to get into the rockers from the front and then pulled big factory plugs out from the back side underneath to get to the other part. Maybe that's how these have to get done too?

Have you had it long enough that you're covered under Krown's guarantee?

 

[Brian71]

Do you park in a heated garage or parking garage at all? That's the most common causes of rust like that.

I can't tell from your pics but if there was an inner rocker structure they're probably getting oil into one part of the rocker the way half of it is so clean but it's blocked from getting into the other half. I have to look at ours. I know with our older OBS one years ago one shop used the drilled holes to get into the rockers from the front and then pulled big factory plugs out from the back side underneath to get to the other part. Maybe that's how these have to get done too?

Have you had it long enough that you're covered under Krown's guarantee?

I have no warranty, I purchased the vehicle used. It sits outside year round.
There were holes drilled in the outer rockers, you just can’t see them in the pics.

 

[Brian71]

Follow Up
Picked up the vehicle yesterday. The body shop did an excellent job, you can’t tell it was even repaired.
The body shop guy did say that there was foam bonded to the inner rocker. That’s what caused the rusting. He also said that no amount of undercoating product would get past the foam.
Here are a couple of pics of the repair.