Thought I'd start a thread about how to spray Fluid Film or equivalent on the undercarriage of a Ram for those of us who live in the northern states that see a lot of road salt. Living in New England, we get the salt air year round and road salt in the winter and I have seen several older 4th gens with rotted out cab corners, rocker panels, door bottoms, tailgate bottom, and rear wheel wells.
To do this you will need the following:
-Fluid Film, 1 Gallon and 1 spray can or 6-8 spray cans if you don't have the following kit
-Ideally you want this kit, you can use the gallon conainers which is cheaper in the long run
Fluid Film Kit for Compressor
-360* Wand for the spray cans (the above kit comes with it but you can buy it separately)
Spray Can 360* Wand
-80 Grit sand paper for any scaly rust
-1/8" drill bit and drill
-Clothes you don't care about
-Tarp of some kind to keep the Fluid Film from getting on the ground
-Tools to remove front and rear wheel well liners and tailgate access panel
First thing you're going to want to do is thoroughly wash the under carriage of your truck. Spray everywhere you can get the sprayer including inside the boxed frame. I usually put my truck on ramps to do this for ease of getting under the truck and it help the water drain out of the frame. This is something I would recommend doing every April or May after the road salt has disapeared anyway. Let the truck dry for a good solid 24 hours or better yet a few days.
Next put the truck up on ramps/jackstands/jacks as high as you can do safely. A lift would be ideal. Remove the spare tire.
Now comes the fun part. Give the frame and underside a good visual inspection looking for any flaky scaly rust and get that off with the sand paper or screwdriver or whatever you can. Surface prep isn't needed for Fluid Film, just removal of loose rust.
Once you're satisfied with that its time to start spraying Fluid Film first inside the crevaces and then liberally on everything else. Try to avoid rubber parts, bushings, and the exhaust system if possible. The following directions are assumming you have the kit that works on an air compressor but you can do all of this with spray cans and the 360* wand.
Start with the hard to reach areas first. The areas to pay particular attention to are inside the entire length of the boxed frame, body mounts, bed mounts, cab supports, frame crossmembers, gas tank straps, above the rear wheel wells, bed supports, wheel well lips, inside the front fenders where there is a fiberglass tape, and anywhere else that you can get the 360* wand. If its the first time doing this, coat it liberally, then coat it again. It won't hurt anything. I stick the wand inside whatever I'm trying to coat and then start spraying as I slowly pull it out. THis way the wand won't scrape the coating off. You will also want to get the gasket between the bed and the cab as this is notorious for rubbing the paint off the cab which will rust if not treated.
I always hit my parking brake linkages
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Picture of the fiberglass tape on the inside of the front fender
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Picture of the rust forming under the fiberglass tape
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What can happen if rust forms under the fiberglass tape
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Great places in the front frame sections to get your 360* wand inside the frame
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What can happen to the cab if the gasket between the cab and the bed isn't rustproofed
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This is where you want to get the 360 wand up into to prevent the rear wheel wells from rotting out
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The gas tank straps mounting plates have a huge design flaw. There are no drain holes in them so the water/salt/dirt gets inside and just sits there rotting it out. You are going to want to drill drain holes in the two drivers side strap mounts as well as the 2 crossmember attachment points on the passengers side. I used a small drill bit for a pilot hole and then a 1/8 in bit. Don't lie directly under them or you will get a bath in rusty water! Check this thread out for what can happen if you don't take care of this asap:
http://www.ramforum.com/f41/frame_rotting_out-99925/
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Take out as many of the rocker panel plugs as you feel necessary to get the 360* wand inside the rockers to coat them with Fluid Film. There are 2 cavaties inside the rockers. There is an outside cavatiy which you can access from the plugs on the outside bottom of the rocker panels, and the inside cavaty where you will have to remove the tape on the back side of the rockers. Make sure to get the cab corners. A great place to access the cab corners is the plug on the rear door jam for the seat belt bolt.
Plug to access cab corners with the 360* wand
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I found this set of plugs on Amazon that fits decent in the holes that were taped over on the back side of the rockers:
https://www.amazon.com/gp/product/B01N7W7I0C/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
If anyone has found something better please let me know.
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Bottom rocker plugs
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Then switch wands to the straight spraying wand and coat everything you can except the exhaust system, rubber componants, tires, etc. Definitely hit the inside of the rear bumper and above the rear wheel well where the brace is spot welded to the rear quarter panel. This is where they rot from the inside out. Next move outside to the wheelwell and thoroughly coat the outer wheel well lip with Fluid Film. This will start to rust from all the flying salt water spray from the tire. I find the spray can works best for this. This will most likely need to be reapplied at least once throughout the winter.
Once you've hit the undercarriage, its time to get the door bottoms. There are 2 drain holes on all the doors and the only wand that will fit in those holes is the spray can 360* wand. Again I use the same technique as under the truck, stick the wand as far in the door as it will go and then spray while pulling it out of the drain hole. Make sure to get Fluid Film into the corners of the doors. I would recommend taking the bottom weatherstripping off to make it easier to get the wand into the drain holes.
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Next go to the tailgate and remove the access panel. Grab the 360* wand and push it down to the bottom of the tailgate and coat the inside. There is a panel about halfway up the the tailgate inside that has several small holes you can get the wand through. You may also want to stick the spray can 360* wand in the drain holes as well.
Last place to go is to the hood. The corners of the hood next to the grill will corrode over time if not treated. There is no place for the moisture to go. Fortunately theres a hole in the underside of the hood right next to this corner to get the spray can 360* wand inside to treat this corner.
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What will happen to the hood if you don't get something oil based in these corners
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Congrats, you just helped to protect your truck from the evils of road salt. Once you do this the first time every application after gets easier because there is always some remnants of the previous application. This is essentially what Krown rust protection does and I would love to have it done to my truck every year except the closest Krown dealer is 600 miles away.
Couple things to keep in mind. The 2500 and 3500+ trucks have different frames and suspension components but the procedures I've outlined will work for those trucks as well as many other vehicles. The door bottoms and tailgate bottom will drip for a few days after application. The smell from Fluid Film will go away after a week. Fluid Film continues to creep into the cracks and crevices for weeks after its applied.
If I missed a critical area, please post the area with a pic if possible. Also any other products or ideas for rust prevention I didn't cover please post them!
