Flushing rocker panels

MarkB_MI · May 27, 2020

Here in the rust belt, rocker panels usually rust out long before the rest of the car. And pickup bed wheel wells are another bad spot for rust. I finally got around to doing the spring cleaning on my '17 Silverado, and decided I should try to flush out the rocker panels. Looking under the truck, I see there are several oblong openings along the inside bottom of the rocker panels, each about an inch long. I assume they're drains. So I took a hose and shot water into each of the drains until the water coming back out the other drains was clear. I didn't get much dirt out, which I suppose is good.

I also found eight large openings on the inside of the bed: two above each wheel well and one at each corner. I flushed those out as well and a LOT of mud came out. This was AFTER I'd spent half an hour at the car wash cleaning out the wheel wells and underbody with a wand. Hopefully I got most of the salt out.

Anybody else flush out their rocker panels?

David G · May 27, 2020

I do, makes a world of difference

Leroy · May 27, 2020

When they are already gone by time vehical is gotten what is left to flush?

David G · May 27, 2020

I believe that regular thorough under body washes do more good than any undercoating.

gab · May 27, 2020

My 2013 Silverado has five or six round plastic plugs under and behind each rocker that I pull and hose out now and then. For the rear I just remove the two screws in each tail light and blast away with my pressure washer. Was just thinking about that this morning, it's due.

Michael Soldan · May 27, 2020

It is good to wash out underneath where ever you can. But the most important thing you can do is apply an undercoating. Fluid film is the best I have found. After the truck has dried from washing apply in spray can of buy bulk and use your own sprayer. I pull the tail lights on my F150 and can spray way up and ahead over the inner wheel wells where rust starts. I put the nozzle in the slots on the rocker panels and liberaly coat inside them. I live in southern Ontario where we see lots of salt on the road. Keeping a truck clean and yearly undercoating can preserve them from Rust

showcrop · May 27, 2020

Michael Soldan has very good program, very similar to what I do. I add one step. I spray with WD-40 a day before my rust proofer, and let it penetrate for a day in case there is moisture ciontained in dust. I get between the inner and outer fenders from underneath. It is all very quick and easy and very effective. My truck is an '06 purchased new.

David G · May 27, 2020

The WD40 is a good idea.

rlp in Co. · May 27, 2020

I wish they would quit salting the roads.

Mike M · May 27, 2020

What was it back in the 70's sometime ? there was a big ta do about rust free rocker panels ? I think these were galvanized metal ? I wonder when manufactures got away from these and why ? I'm guessing a cost saving measure. Same with when they were showing some sort of black primer coating ? They had a vat of it and dipped the bodies in it. I remember seeing a picture of it or TV commercial or something.
I was starting to think Fluid Film would be good, but have since found out otherwise ! It may still be good on inner body areas but on outer areas it washes off from all the stuff blasting it.

Kerwin · May 27, 2020

Yes, I flush the rockers, under the front fenders, and rear fenders on my truck at every wash and especially during the winter if it's been in any salt. I probably spend more time spraying under the truck then on the upper part! Rust out comes from the inside out in probably 90% of the situations that I've seen, so I try to do as much preventative cleaning as possible. It's amazing and sad on how many newer trucks are still rusting out above the rear wheels...good engineered obsolescence.

Ultradog MN · May 27, 2020

Well Mark,
As much as you hate this administration and the guy at the top I'm surprised you didn't blame him for rusted rocker panels - a la yesterday...

MarkB_MI · May 27, 2020

Well UD, as much as I abhor corruption and incompetence, it's plain old calcium chloride that's responsible for our rusted vehicles, not our beloved president.

VicS · May 27, 2020

Guess you guys don't know about Fords. I read a article from Dodge truck. This guy said all you do washing under your vehicle is activate the salt etc. Best to leave it alone. Don't kill the messenger. LOL.

showcrop · May 27, 2020

(quoted from post at 16:01:32 05/27/20) Guess you guys don't know about Fords. I read a article from Dodge truck. This guy said all you do washing under your vehicle is activate the salt etc. Best to leave it alone. Don't kill the messenger. LOL.

Vic, I remember maybe 15 years ago a friend got a new Ford pick-up that he used for a lot of snowplowing. He was determined to treat it right and make it last, so he kept it in his heated basement garage and washed it off after every time that it was out in the salt. Well, after four years he could see some rust so he took it to a friend who had an auto-body shop to see about some intervention. The friend looked at it and advised him that it would cost too much. It was already too far advanced. So I have to agree with your friend that just spraying off is worse than nothing. You have to crawl under or get it up on a lift to flush it enough to get the brine out of where it is eating the steel. Fluid film will wash away from the outer surfaces but it lasts for months in the inner places that a flush doesn't get into where the brine would be eating away. My truck is fourteen years old and has insignificant rust.

MarkB_MI · May 28, 2020

> This guy said all you do washing under your vehicle is activate the salt etc.

Salt is hygroscopic, so unless you live in the desert, it will absorb all the water it needs to promote corrosion directly from the air. Not to mention any salt deposited on the vehicle is going to get wet every time you drive in the rain. The only way to stop salt from promoting corrosion is to eliminate it, which is admittedly not easy to do in many nooks and crannies of your vehicle.

MarkB_MI · May 28, 2020

> Vic, I remember maybe 15 years ago a friend got a new Ford pick-up that he used for a lot of snowplowing. He was determined to treat it right and make it last, so he kept it in his heated basement garage and washed it off after every time that it was out in the salt.

I don't think a plow truck is a particularly good test of the effect of washing, unless maybe you had two identical trucks, one washed and one unwashed. A plow truck with a salt spreader is going to get exposed to a lot more salt than most vehicles.

In my county, salt is a problem year-round, because the county road commission has several brine wells. They use salt water from their brine wells on the gravel roads to reduce dust, but the resulting mud on your vehicle is almost impossible to remove and is highly corrosive. A drive-through car wash with underbody flush does a decent job of removing plain old salt, but it will hardly touch that mud.

showcrop · May 28, 2020

(quoted from post at 03:42:47 05/28/20) > Vic, I remember maybe 15 years ago a friend got a new Ford pick-up that he used for a lot of snowplowing. He was determined to treat it right and make it last, so he kept it in his heated basement garage and washed it off after every time that it was out in the salt.

I don't think a plow truck is a particularly good test of the effect of washing, unless maybe you had two identical trucks, one washed and one unwashed. A plow truck with a salt spreader is going to get exposed to a lot more salt than most vehicles.

In my county, salt is a problem year-round, because the county road commission has several brine wells. They use salt water from their brine wells on the gravel roads to reduce dust, but the resulting mud on your vehicle is almost impossible to remove and is highly corrosive. A drive-through car wash with underbody flush does a decent job of removing plain old salt, but it will hardly touch that mud.

Mark, I don't think that a truck driving around in salt for eight hours is going to get any saltier than one that is driven for a half hour. The salt from a spreader is on the top and easily removed compared to the salt spray mist that gets carried up underneath at road speed.

BarnyardEngineering · May 28, 2020

(quoted from post at 11:05:56 05/27/20) What was it back in the 70's sometime ? there was a big ta do about rust free rocker panels ? I think these were galvanized metal ? I wonder when manufactures got away from these and why ? I'm guessing a cost saving measure. Same with when they were showing some sort of black primer coating ? They had a vat of it and dipped the bodies in it. I remember seeing a picture of it or TV commercial or something.

They were gimmicks that did not work and did not appreciably increase sales. If they continued pushing them they most likely would have been sued for false advertising.

Blackhole49 · May 28, 2020

I live in SE MI. This is my 08 Silverado. Never flushed out anything. Did have Texaco undercoating applied when I bought it new. On a hot sunny day, the undercoating will still bleed out.

MarkB_MI · May 28, 2020

> I live in SE MI. This is my 08 Silverado. Never flushed out anything. Did have Texaco undercoating applied when I bought it new. On a hot sunny day, the undercoating will still bleed out.

I'd say that says more about the effectiveness of the factory corrosion control rather than about your undercoating. I don't think much undercoating will make its way inside the rocker panels, nor do I think the undercoating guys would have removed the wheel well liners to get back around the wheel wells.

FWIW, my son's '04 Silverado is still rust-free, although it did take a four-year break from salt in Nevada. No undercoating or other aftermarket treatments.

Blackhole49 · May 29, 2020

I disagree about the undercoating, but if Chevy builds the so good, why waste your time rinsing them out?

MarkB_MI · May 29, 2020

> I disagree about the undercoating, but if Chevy builds the so good, why waste your time rinsing them out?

Fair question. I figure I'm only facilitating the way it's supposed to work. But I posted my message to get some feedback from others.

You may not be aware that aftermarket undercoating or rustproofing can void the factory rust-through warranty.

showcrop · May 29, 2020

(quoted from post at 11:01:35 05/28/20) > I live in SE MI. This is my 08 Silverado. Never flushed out anything. Did have Texaco undercoating applied when I bought it new. On a hot sunny day, the undercoating will still bleed out.

I'd say that says more about the effectiveness of the factory corrosion control rather than about your undercoating. I don't think much undercoating will make its way inside the rocker panels, nor do I think the undercoating guys would have removed the wheel well liners to get back around the wheel wells.

FWIW, my son's '04 Silverado is still rust-free, although it did take a four-year break from salt in Nevada. No undercoating or other aftermarket treatments.

My opinion is that an undercoating that will still bleed out on a hot day after 12 years is one that goes on fairly thin and under high pressure that can be sprayed into pretty much all nooks and crannies, yet sticky enough to be still there after 12 years of dripping a little out.. Years ago my younger brother worked at a shop where they installed Ziebart. They had a large array of special applicators for getting into different places on the car. If there was not an adequate hole they would make one with a hole saw. When the job was complete they would put the yellow Ziebart plugs in the holes. There would have been no thought of removing a fender liner, because they had the tools and procedures to get behind it as needed. They had a book of procedures for most models to consult to ensure getting into all of the cavities. It is not black magic just common sense.

Blackhole49 · May 30, 2020

My picture speaks for itself. After 12 years, not too worried about any warranty.

JMOR · May 30, 2020

(quoted from post at 16:57:58 05/30/20) My picture speaks for itself. After 12 years, not too worried about any warranty.

never could get the rocker panels in the toilet to flush them! :shock:

Flushing rocker panels

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