I just checked under the car today (1985 Chevy Caprice) to look at the condition of the floorboards. There is a lot of rusty metal down there. In the center there is a 3 foot wide swath which is coated in transmission fluid, from a slow trans leak which has preserved that area, where it has blown back from wind during driving. No rust where there is trans fluid. :)
I was thinking of coating the other, rusty areas of the floorboards with something like chassis grease, or motor oil, trans fluid, or spraying it with Permatex. My instinct is to go with the chassis grease, lots of it, applied with an old rag.
Is there some other grease that is specifically made for coating rusty metal to prevent further corrosion ??
i have heard of sparying diesel fuel at the underside of a car. apparently that works quite well. i am not sure about the environmental side of this. heating oil would also work as it is pretty much the same stuff. Don't use gasoline, you will incinerate yourself and your car.
I have an extended family member who's a depression era farmer. He never gets rid of anything and rust proofs everything.
When he does an oil change (pinches every penny but knows that money spent on oil saves much more in the end) he saves it to a drum. He has two very large steel beams on their sides (that are wider than any wheel base he owns) coming off a bank on one end and supported by two telephone poles on the other. He regularly pulls every vehicle or piece of equipment he has out there and fills a paint gun with oil and shoots every inch of it underneath. He also has a gizmo he rigged that shoots a stream and gets it in any weep holes of frames and etc.
I can tell you that his stuff lives forever under extreme conditions, but... his family, when they still lived at home, used to avoid leaving their cars around when he was 'oilin' things. They had very full schedules until they were sure he was on his next yearly routine... the reason being that those cars stunk like the dickunz afterward. As an old farmer he could care less but as a teen or young adult impressing friends or chicks it was mortifying for a while... but he regularly still runs equipment and vehicles that have incredibly high hours and miles on them.
You also might run into some guff from environmental extremist sorts if you were to do this in, say, the back yard of your gated community or anywhere else neighbors can neb into your affairs. >:-) As mentioned in another post there is also the flammable aspects that require some common sense in their approach.
Another option would be to clean all the oily goo and undercoating off, then coat with something like POR-15 then follow with some fresh spray undercoat.
With a cheese shredder, cut the wax into the turpentine, stir until the wax has dissolved, (takes a long time; you can use very low heat (a warm room) to aid but be careful) and thin with the machine oil to a brushable / sprayable consistency. Apply liberally.
I've made this and used it. Works very well on inner panels and seams. Once it fully hardens it is kind of a rubbery wax that bends with the panels.
You have just described automotive undercoating, except that undercoating also has some strong ahesive properties to keep it in place. Available in a convenient spray.
You DO want to borrow a lift to apply the stuff... it is no fun working on jack stands with it. Either way wear goggles.
Previously every year I would have to wire wheel, use Rustoleum primer, and then exterior paint. The rust came back every year starting in the seams. I'm going on two years now and there is not a hint of rust anywhere.
I also used POR-15 on a air conditioner grate that was entirely rusted. It too had to be re-painted every year until POR-15. The grate is on its third year and still no rust.
I don't mean this to be rude at all, just realistic.
You have an '85 Caprice with rusty floorboards and (at least) one rusted through fender. You're dealing with a 1k car that very likely has terminal rust issues. Just drive the dang thing and be happy with it until the rust gets bad enough that you want another one. Save the money you would spend trying to fix it and get you a better one next time that doesn't have the rust issues.
Oil will slow existing rust, sure. But it's an either/or treatment. You either try to degrease it completely and paint it with something like POR-15, or whatever Eastwood's equivalent is (I'm not familiar with the Permatex stuff) OR you treat it with oil and try to "hold the line."
Well, you have a 23 year old car that shows visible rust on the floorboards. Was the car used in snow and on salted roads? If so you probably have a lot more rust than is visible. The chances are excellent that there is a lot of rust in areas you can't see as well. Coating the rusty areas with oil or some other product will slow the visible rust down but won't do much for the rust you can't get to.
If you are planning on keeping the car you might want to look into having the underside inspected and possible rebuilt.
Yes, this car has been driven in a salty northern winter every year.
I've been looking for a replacement car, like another Caprice with no rust, or a Crown Vic / Grand Marquis. But this 85 keeps running fairly trouble-free except for cosmetic problems, so I keep getting it past inspection "one more year" again and again. It's not costing me much money at all, just some time, and I'm willing to spend a few hours on the weekend to patch it up. At the present time, it looks pretty good, I must say, after I painted it. :)
undercoating straight over rust (at least the usual "rubberized undercoating" that comes in a spray can) is a recipe for disaster. I'd rather have bare metal than that stuff, it won't rust as quickly.
Back in the 1950s, I read an article in Popular Mechanics magazine about a guy who bought a new 1950 Ford car.The first thing he did with his car was to apply roofing tar (that stuff you can buy at Home Depot, Lowes/similar building supply stores) to the bottom of his car, then he removed the interior door panels and he applied roofing tar to the inside of the doors.He said it helps rust proof the car and makes it ride quieter too. cuhulin
Is it? I have always used the Permatex stuff and it seems to be okay on slightly rusty surface, it at least doesn't trap water and make the problem worse or anything. I have also used it in combination with the Locktite rust stabilizer too. Am I to be expecting a big problem a decade down the road?
Maybe, I don't know about the Permatex stuff in particular; I haven't seen that brand sold locally and to be honest I don't know what *is* - but I have seen water get trapped under home-applied undercoating before ( and to be honest, some factory-applied undercoating as well) making a whole mess of things.
Bottom line, I far prefer paint to undercoating.
I do like the light-colored waxy stuff that is common on German cars. that stuff really seems to work well, and it flows when it gets hot, so it is to some extent self-healing, although of course that means in hot weather you get a little goo out the bottom of the door drains etc. - a small price to pay IMHO.
You might pull the carpets up to see if there is any rusting or perforation visible from the inside. You might also consider having a body shop take a look at the undercarriage and get their take on how sturdy it is. They are a reliable car and you've certainly got your money back on this one. Keep it running for as long as possible and consider spending a few bucks to do so. The alternative is spending a lot more money an another car.
A family member in California had the floorboards rust completely through on a chevy wagon after 12 years, so it can happen. Cause was water dripping ino the carpet because of a bad door seal.
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