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'94 Corolla Paint Issues

2K views 18 replies 7 participants last post by  Pete Suhman 
#1 ·
I have a '94 Corolla that I have driven for many years as a work car.I am noticing small(10mm-20mm) regularly spaced patches of rust on the roof.The points are raised as if the rust is pushing the paint up.My question is what would cause this and what can I do other that painting the roof to stop this rusting?
 
#2 · (Edited)
Hate to say it, but it sounds like it's rusting from the inside out. Does it have a moon-roof or anything? Any leaks in the car?

But I guess that if the paint is in bad enough shape, that it might be all on the outside.

You could paint it yourself if the McParts stores still carry paint code-specific rattle bombs in your color. But you would need to sand down to shiny metal, and prime it first.
 
#3 ·
Well,that's exactly what I did not want to admit,it does appear to be rusting from the inside at some type of contact or weld points.No moon-roof but the trunk has a small leak.The rest of the paint looks great for a work car with no other rust.
Would removal of the headliner reveal internal rust areas?
 
#4 ·
Kind of...

From what I've seen, (of mostly other makes of cars) there are cross-member-style braces which run across the underside of the roof skin from side to side, and are bonded to it in some way. If the rust is between the skin and the brace, then you're kind of screwed - as far as the proper DIY style fix goes.

Even if you can't directly attack the rust, you can still keep any pinholes plugged and sealed, thereby keeping the rain out.

It's like you got a sort of late-bloomer sunroof or convertible...
 
#6 ·
Not in the parts of the underside of the roofskin, which are (probably spot-)welded to those cross-braces, which sounds like where-from the problem might stem.

Best way would be to go through the roof skin from above. Drill out the spot welds, and cut the skin. Then address any problems with the braces, and weld in a patch. Doesn't sound like the OP is that dedicated to the car though.

The biggest concern is keeping the affected areas from leaking through to the inside of the car, and there are still ways to accomplish this cheaply.
 
#7 ·
Thanks much for all the help !!! I guess I need to spend some time stopping the water from getting in as I really do like the car!I have a friend that maybe I can get to tackle the body work.Do you think that replacing the seal in the trunk lid will help?Any other suggestions would be much appreciated.
 
#10 ·
The Corollas made at the Fremont plant during those years had batches of bad paint; especially the metallics.
You ain't kidding either!!! My 94 needs a little rust repair on the roof also. Thankfully it's not the middle of the roof. The grooves(?) and above the door trim(?) is where it is(if you know what I mean... no pun).
 
#12 ·
Most likely Toyota 040. Still doesn't mean it may not have cracked paint or pinholes here and there that let water through. Which then collects in the channels of the reinforcement ribs and rusts out from underneath.

Unfortunately, if this is the case, to really cure it, you'll need to cut off and remove the roof and/or the ribs to grind off all the rust. Then use a conversion coating to get the stuff you can't reach or see. Then an inhibitor coating before regular primer and paint.

I've done this with classic car restorations, hot-rods and racecars. Depending on how much work is involved and how much you can do yourself, you're looking at $1500-10,000+.
 
#11 ·
Luckily, mine had lived most if its life in Ca with very little rain, and no snow or salt to deal with. And it STILL needs a repaint. Strangely enough, it's the roof that's the worse. The clearcoat is completely gone. Most of the blue metallic is gone and it's just primer showing. :(
 
#13 ·
I don't know what part of the world the OP lives in, but I would be very surprised that just rain water would cause a rust through condition, from the inside, in far less than 20 years (assuming the problem wasn't there from day one). Salt and other things can cause serious damage in a relatively short period, though. I grew up in the rust belt, but have lived in the south for the past 24 years, and rust through conditions are almost non existent here (my Jeep had a few pinholes where the roll bar met the body, but CJ's are extremely prone to rusting). The sun is very damaging to paint (and everything else!). My GUESS is that it's all outside damage. Try taking a closer look to see if there are any holes through. You may have to sand or grind to see. How does your headliner look? Water damage? Musty smells? I've had cars with leakage to the interior, and there has always been a musty smell present.
 
#14 ·
My 93 had this issue and a friend with a Mazda has a similar problem. We came to the conclusion they are rusting spot welds. It's tedious but you can fix it by grinding down each bump to clean metal (shouldn't take too much, it's happening just below the paint) with a dremel and filling it with bondo, then sanding to shape and refinishing the roof. Didn't have any issues at all doing this but took FOREVER. My advice is to work in small sections at a time so you don't go insane trying to fix them all in one shot.
 
#15 ·
Yeah, once you have rust, it's pretty much impossible to get rid of it permanently. For the longest-lasting rust-removal, do the following (still won't be as permanent as not having rust start at all).

1. Grind, blast, sand, wire-brush off as much of it as you can. Take your time and use different tools to get at all the rust in its nooks and crannies (look up how ferrous & ferric oxide feed off each other).

2. Then use a rust converter product that chemically reacts with the remaining hard-to-reach rust and changes into something more inert (still not 100% foolproof though). Something like CRC - Marine Rust Converter Primer or Rust Bullet - Metal Blast

3. Follow up with a rust inhibitor treatment such as Rust Bullet Standard or POR-15 Rust Preventive Coating.

4. Finally bondo, coat with primer & paint like normal.
 
#16 ·
Thanks again for all the reply's! I just found a local retired body man who still does occasional body work and after looking at the car he stated that the rust was all external and that he would repair and paint the roof to fix my problem!
Now all I need is someone that can be trusted to rebuild the engine!
 
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