Underbody Flushing - Actually Worth It

[Donald]

Where in Hagerstown?

Summit Truck Outfitters

 

[Snagglefoot]

Went through the first winter with the 24 Silverado. On my previous Chevys (04 and 13) I was religious about flushing the underbody every spring. They both still rusted in the usual Chevy spots. For this truck I plan on spraying between the bed panels (over wheel arches) and cab rockers with oil. Is it possible that doing all that flushing actually makes stuff worse? I mean with garden hose sprayer, I never trusted those car wash jobs. Is it possible that a vehicle would last longer if it was unmolested (with the exception of occasional oil spray)? I am referring only to the sheet metal. I’ll probably still try to hose the frame off? I’ve kept up with that pretty religiously with the spray stuff gm recommended to cover any imperfections in the wax coating (I can’t remember what its called, can is in the garage).

You are in luck with the 24. I believe Chevy went with the heavy duty plastic liners inside the wheel wells. I would still try to jet water at the interface between the plastic and the steel. Another trouble spot has been the dogleg of the fender just aft of the front wheel. I certainly hope Chevy has done a better job than 20 years ago.

It would be good to have a look at how things are configured back there and make sure it’s soaked in your favourite corrosion inhibitor. Here is a shot after I put a screwdriver through the sheet metal on a 2008 Suburban. That section is now fibreglass and bondo on mine. Back then it was virtually designed to store road debris and dirt.

I think it’s worth it to spray in the spring to get any salt off it before the corrosion gets going and either get it sprayed completely or use spray cans in the trouble spots.

 

[Donald]

You are in luck with the 24. I believe Chevy went with the heavy duty plastic liners inside the wheel wells. I would still try to jet water at the interface between the plastic and the steel. Another trouble spot has been the dogleg of the fender just aft of the front wheel. I certainly hope Chevy has done a better job than 20 years ago.

It would be good to have a look at how things are configured back there and make sure it’s soaked in your favourite corrosion inhibitor. Here is a shot after I put a screwdriver through the sheet metal on a 2008 Suburban. That section is now fibreglass and bondo on mine. Back then it was virtually designed to store road debris and dirt.

I think it’s worth it to spray in the spring to get any salt off it before the corrosion gets going and either get it sprayed completely or use spray cans in the trouble spots.

View attachment 314755

Some people use matching color duct tape to fix rust areas. It's certainly cost effective and time efficient.

 

[Snagglefoot]

It’s crazy that I’m describing a problem from almost 20 years ago and I’m wondering if Chevy got the problem fixed. So when was the last rusted out front fender dogleg?

 

[KrisZ]

You want to keep that truck rust free long term? Proper rustproofing is the only proven solution.
Look into it, there is plenty of info on this forum alone.

 

[JoelB]

You want to keep that truck rust free long term? Proper rustproofing is the only proven solution.
Look into it, there is plenty of info on this forum alone.

Totally agree. Frequent washes do not stop rust. The vehicle needs to properly coated on it's internal cavities to stop cancerous rust.

 

[2002 Maxima SE]

Went through the first winter with the 24 Silverado. On my previous Chevys (04 and 13) I was religious about flushing the underbody every spring. They both still rusted in the usual Chevy spots. For this truck I plan on spraying between the bed panels (over wheel arches) and cab rockers with oil. Is it possible that doing all that flushing actually makes stuff worse? I mean with garden hose sprayer, I never trusted those car wash jobs. Is it possible that a vehicle would last longer if it was unmolested (with the exception of occasional oil spray)? I am referring only to the sheet metal. I’ll probably still try to hose the frame off? I’ve kept up with that pretty religiously with the spray stuff gm recommended to cover any imperfections in the wax coating (I can’t remember what its called, can is in the garage)

We don't have much salt used here, primarily brine, however I take all the vehicles to a touchless car wash between snow accumulation which is about 3 to 5 times during the winter months. I wait until after the snow melts and we have a decent rain to wash salt and brine off the roads. Then hit the wash to rinse the underside and body.

 

[GenSan]

I have an unlimited touchless car wash plan that I take advantage of during the salt winter months. It costs $35/month and the regular price per car wash is $10-15 depending on options. I have done a maximum or 2 car washes per day for the weeks that the salt trucks are laying it down thick. I also spray Krown on underbody when I get under for oil changes or rotate tires. My vehicles always look great and have the least amount of rust.

 

[Donald]

I have an unlimited touchless car wash plan that I take advantage of during the salt winter months. It costs $35/month and the regular price per car wash is $10-15 depending on options. I have done a maximum or 2 car washes per day for the weeks that the salt trucks are laying it down thick. I also spray Krown on underbody when I get under for oil changes or rotate tires. My vehicles always look great and have the least amount of rust.

NH Coatings does not recommend undercarriage washes when a vehicle is treated. Unsure about the others. Maybe rinse with garden hose but not high pressure.