Hi, I drive a 2003 F-150 SCrew, and I just moved from phoenix arizona (really hot temps) to Flagstaff arizona (really cold temps) and I have been hearing that when the City salts the icy roads in the winter, it damages the underside of your car. Is this true? And if it is, is there anything you can do to prevent it? Like something you spray or paint on? Thanks!

 

Yup. Salt is a killer for vehicles. The only thing that you can really do is get your truck undercoated and make sure to wash it often in the winter.

 

does the undercoating help alot? Is it worth it?

 

Undercoating is a goopy substance that covers the rustable metal to keep the air out. In theory, this works really well.

There are several problems with undercoating.

1. Small gaps and imperfections during installation - allows salty water to get behind the undercoating where you can't see it, until it's too late and chunks of undercoating falls off with rusty flaked metal stuck to it.

2. Often times during installation, the designed in drain holes get plugged, which in turn allows salty water to pool inside various parts of the body, which in turn *increases* the opportunity for rust to form, again, where you can't see it until it's just too darn late.

3. If you have to repair an area later, undercoating makes wrenching bolts more than annoying and certainly increases a risk of fire if you're using a welder, or a plasma cutter to do body work, possibly from #1 and #2 above.

What I do, is wash the truck in the winter. Some car washes have "truck mode" where there huge rollers don't bang on the vehicle because of the height, but it still gets most to all of the salty water off, even underneath.

Many places have self-serve powerwashing booths, so for a buck or two you can wash it off yourself for less money.

Or, you can do what I did. I have a hot, and cold water feed in the wall of the garage feeding a bathroom just above the garage, and I brazed in a "T" and a ball valve and a brass air-hose quick connect fitting. I have a PVC air hose just for water, with a homemade "power nozzle" boom on the end, with a 45 degree angled head. This allows me to hose off the entire bottom of the truck, without sticking my body too far under the truck as getting wet in the winter, well, sucks. This is also why I tapped the hot water line rather than the cold water, so if I get splashed it's only mildly unpleasant rather than frostbite causing frigidness.

You can use a garden hose and one of those "power nozzles" which work okay too, but you have to reach further under the truck and you're hand/arm/shoulder might get wet more.

 

Thanks for the tips Frederic, I think I'll stick to washing my car more frequently than applying the goo, as you recommended.

 

You're welcome.

My biggest objection is fire, due to welding and plasma cutting to do body or frame work as necessary (or adding "features"). Getting undercoating off is just nasty and no matter how much you grind at it, chip at it, scrape it, or heat it with a propane torch "gently" there's always some residue which ends up burning off when you cut, torch, weld, or braze. And it smells nasty too, I can't imagine that makes for good breathing.

Newer vehicles like yours also have a lot of anti-rust materials built in. Ford uses galvanized panels in the bottom of the body. Also the frames are high-tensile steel which seems to rust much slower than ordinary mild steel. Also the primers, paints, and clearcoatings have improved in leaps and bounds so your 2003 has a much better chance of surviving salty roads than my 93, which by today's standard is made of poor materials lmao.

But for what a new F350 crewcab costs, I'm happy to cut off a little rust here and there once a decade and replace parts that fall off. I definately got my money's worth considering the truck new was $17,500 and I have 409K on the odometer.

And finally, there are no more primer spots anywhere on the truck

 

Wow, that's pretty impressive! Well hopefully I can make mine last as long! Its only got 75K on it so I should be could for a while. I hope. I try to take pretty good care of it though, that's why I'm on here talking to people like you to gain a little bit of knowledge in caring for and modifying it a bit.

 

Once the underbody has been exposed to salt, even driving thru an area that uses it, NO AMOUNT of washing will remove the salt. Salt can be carried into an area by vehicles from other areas. It is just plain physically impossible to get the salt off unless the vehicle is immersed in fresh water for months etc like the Mercury space capsule. Undercoating a vehicle at that point just seals the salt in and increases a type of corrosion called oxygen concentration corrosion.

 

Now catch this...I was watching a program about coastal bridges and in Oregon - they came up with a process to treat a bridge for oxidation/prevention.

The main problem was salt water getting to the metal rebar which would then expand due to oxidation (10 times it's size or something like that) and, like water freezing would split the concrete more etc.

Science has provided a unique alternative. After they remove and repair the exposed or swollen metal they apply a coat of zink oxzide to the outside or concrete part of the bridge like a paint- it's done in an application that uses a lot of heat that creates a light like stick welding- special equiptment. The metal rebar is tied electrically to the zink ozide with a low voltage which then sacrifices itself by drawing the current that oxidation creates away from the metal to the zink- which will have to be replaced every 15 years or something like that. I knew about the oxidation process I thought but to abate it eletrically is way cool.

I've been a believer in the zink oxide products like found in por's metal ready and have been treating all exposed metal with it a couple or three times before applying any type of cover. I am a big fan of both the urathane/polyurathane bedliner type stuff and even more-so with the por 15 itself. The por 15 is the only stuff i'm aware of that gets harder the wetter it is (cept for me) and was initially designed for saltwater apps.

So I would and am treating all my vehicles, as time and $$ allows with por 15 in their 3 step process- except i like my own cleaners better. To me that is the best way to go. And I keep a spray bottle of the metal ready handy and hit everything i own that begins to rust...it abates rust for a long time.

 

can't edit so another post.

There is also stuff other places spray to counter black ice and that crapola is worse than salt i think. It takes chrome apart quickly and attacks everything from metal to paint. Forgot what it is off hand but it does reduce accidents and it's supposed to get down to 24 deg tnight here in Montanaland- had to put a heat light under the hood cause i haven't put antifreeze in the bronco after checking it for another leak- gotta do that this week! Probably not cold enought to do much but with my run of luck lately....

 

What do you use as a cleaner when you apply the POR15?

 

I always prefer to use laq thinner- cuts to the chase- I also have some stuff i can't remember the name of- some guy sold it to me door to door one day when i was weak and vulnerable- works good though.

I'm probably doing it wrong but the results seem to work out- bonds well- etc. I've never been in a position where i was comfortable rinsing rusty sections with water- so i don't

 

That electrical bonding to the zinc is called a sacrificial anode and has been used by pipelines, plumbers, and marine structures, ships, etc, for many years. It is great they found a way to apply it to concrete bridges. They also coat the rebar with epoxy and a new rebar manufacturing process is making the rebar metal itself less susceptible to inter-granular corrosion.

 

I have used a product to protect my truck from the winter salt called Rust Check. This product behaves more like oil when applied with compressed air to the door interiors,hood,rocker panels etc. It creeps into the seams from the inside. I have used it since my truck was new (1988) and still have the original doors , box tailgate and till a front end collision this year had the original hood and fenders. As far as the frame I found this oil spray not effective. Cleaning the frame and under carriage with hot water and removing dirt on the bottom flange of the frame with a putty knife at least once a year was more effective. Looking back I would suggest removing the box once a year to really clean things incuding the top of the fuel tanks. The solid undercoat products I would stay away from as previous posts have indicated. They really dont work and can cause more rust issues than they prevent.The oil spray is applied once a year to maintain the protection.You still have to keep an eye on things as no vehicle is maintainance free.The oil spray while helped a lot but did not prevent some corrosion developing in the inner fender area around the wheel wells on the box. Once you get rust you never get rid of it . But you can control the its rate of destruction to minimize you repair work.

 

Yeah.. I moved from Phx to Montana. When I did I HAD some nice aluminum wheels on my truck, after the first winter I went to wash my truck and noticed my wheels had all this pitting and stuff on them. I used about every type of polish I could find, nothing worked. I thought somebody told me that around Flagstaff they don't use salt, they use hot lava rocks and drop them on the roads to melt the ice.