Under Coating (applying in the winter) (1 Viewer)

[Dirk Diggler]

Not to argue, and I'm fine with agreeing to disagree, but for grins and giggles and arguements sake, how do you know? In other words, have you removed the undercoating to see the stuff under it or are you just saying rust has not broken through the undercoating yet? Again, not to argue as such. This is cool.

I have painted my last two trailers with underoating and they generally last 2 years longer before needing any "rust work". Does this translate to a more protected Cruiser. I tend to think so. I am certain it does not make it worse.

 

[Gauge]

I have done a lot of investigating on this topic over the years. In my opinion, undercoating is better than no coating at all, BUT, as Turbocruiser pointed out, it MUST be prepped properly or it will not work as well as intended. Ridgerunner has posted that he has had good experience with undercoating, but he doesn't say whether the undercoating was done when the vehicle was new or not. I think this makes a big difference. A new frame is a clean frame and will help aid the adhesion process of the undercoating.

I have a good friend that exclusively does antique restorations. He is ALWAYS dealing with rust. A bad undercoating can be worse than no coating at all. The coating needs to adhere to the metal perfectly. If not, condensation will form between the coating and the metal and it will rust worse than if it was not coated, because a non coated frame will dry out with exposure to air, while the coated frame will keep the water trapped slowly rusting away even on the sunniest and driest of days.

Also, most people who undercoat live in cold climates (to protect from road salt). Cold climates is part of the problem. Think of what happens to water when it freezes - it expands. When there is a crack in the road and the water in it freezes, what happens? It becomes a pothole. Same with undercoating. If there is a slight gap where water can get inside, when that water freezes it will crack away the undercoating, or worse, it will push the undercoating away from the frame leaving a space for moisture to get trapped. This is how a vehicle with undercoating can rust worse than a vehicle without undercoating. It all goes back to surface preperation. I would not recommend an undercoating on an older vehicle unless the frame was cleaned properly.

So what to do? My friend who does the antique restoration says OIL. Drain oil works best and costs nothing, but as pointed out is BAD for the environment. I had a Ford Ranger that was rusted out real bad after being only 4 years old. I spent one afternoon with a paint brush and coffee can filled with drain oil and my rust problem was gone forever. I kept that truck for 10 more years without the rust ever returning. It was a real pain in the arse and the brush is not good at getting to hard to reach places, but boy did it work. As Dirk Diggler said, oil is hydrophobic and the water just rolls away.

I don't use drain oil anymore. Every time I climb under the cruiser to grease the driveshaft fittings, I carry a can of WD-40 with me and I spray a light coat over every piece of metal I can see. WD-40 is a light oil and offers little protection, hence the reason I spray again every time I grease the fittings. After 5 to 10 oil changes, I will have a nice base built up and protection for years to come.

Just my .02 and I hope it is helpful.

 

[J.A.P]

Well, here's a new dilemma. I seem to have a small puddle of what looks like oil in my drive. Any chace its overspray on a part that gets hot melting off and dripping? Please tell me it's not the rear main, it's dripping between the engine and trans. You may be seeing a new post from me very soon, after I read many previous post's on the subject of course.

 

[Darwood]

Let me tell you how I have seen undercoating done. Mechanic sprays used motor oil on the undercarriage, actually soaks it down. Then you drive on a dirt, dusty road to cake the dust over the oil. This is suppose to work.

SS

Hey, my truck had this done to it, but I'm not so sure it was intentional.