Frame rust

[malinator]

Seeing as my GM has frame rust I was wondering if all these cars had this problem? Or was it addressed in later years? Theres a few p71s near by that aren't too expensive.

[pantera77]

Depends where. The passenger front bulkhead is fairly notorious on 79-02's, can't tell you how many panthers I've failed for inspection because there's nothing left there. My new 92 looked solid till I gave it the hammer test. Ended up cutting out a bunch of rust and welding new metal in.






The rails themselves like to rot out as well, my old 92 had a good chunk missing on the drivers side. By the time I scrapped it the frame had broken at all four corners, it essentially converted itself to a unibody.




Moral of the story, when you live in the rust belt, don't be surprised to find rotted out frames. The fact there fully boxed on panthers only seems to make them rot out faster.
Personally I won't buy cars from around here, no reason too when there just as cheap down south and rust free. I broke that rule on my new 92 and sure enough am paying for it. The front fenders didn't even last one winter.

[IPreferDIY]

I've always sprayed rust inhibitor on the underside of my cars. My 2000 MGM is holding up fairly well, though the "bulkheads" had developed holes before I knew of the particular problem with them. How much rot can there be in the bulkheads before they would fail a safety inspection?

[gadget73]

The A pillar area on the passenger side is especially bad because the AC system drips there. There are a bunch of layers of metal all spliced together, and the water just runs in between and lays in the boxed frame until it rots out.

[pantera77]

I've always sprayed rust inhibitor on the underside of my cars. My 2000 MGM is holding up fairly well, though the "bulkheads" had developed holes before I knew of the particular problem with them. How much rot can there be in the bulkheads before they would fail a safety inspection?

Completely depends on the laws where you are, who's inspecting your car, and so on. A few small holes I don't care about, but when the lift arm goes through the frame It's time for a new car.

[IPreferDIY]

One of the good things where I live is we don't have annual inspections like I've heard others mention, so I don't have to worry about my car. I was more interested in getting a sense of what I might encounter if an opportunity comes along in the not-so-near future and have to get it inspected before putting it on the road. I'll look into it more if/when the time comes. We do have emissions checks every two years, though they've recently gone with what the computer says instead of using the sniffer. They also want money every year for a license plate sticker, and money every five years for license renewals, but I suppose that's reasonable, even if they can't figure out how to get repaving done without causing so much inconvenience.

[johnunit]

if you're in Ontario, ANY frame hole fails on a body on frame car. There's a bit more leeway with unibody cars, but if you're talking any panther, a rot hole is a fail. Even repairs will sometimes leave mechanics on the fence.

[DerekTheGreat]

Spray oil on everything, that's my solution. If you want to be economical about it save the stuff from your oil changes, thin it out a bit with some mineral spirits and then spray it everywhere once a year in the summer months. I'm close enough to Canada to take my stuff to Santing's OK Tire Store to have my garbage Krowned.

[malinator]

The rust belt is horrible, but I've been around older cars that never had that problem. You said 79-02 were notorious for it, did they change anything after 02? I wouldn't want to buy a later model and have the frame rot out after a few more years.

[DerekTheGreat]

I've seen enough of the whales made 02 and after with rusty fenderlips & whatnot, bet their frames were crusty too. Bottom line is that all cars will eventually rot out and die due to cancer. It's the salt water mix that destroys cars and if anything, the new ones are even worse. The old cars you see that have no rust weren't subjected to salt on a regular basis. Sure, things will rust when exposed to high humidity, lots of rain or water pooling but its the salt that accelerates it. I've been working in the corrosion industry for over ten years and that's the recurring theme. What do we use to test coating specimens? Water plus salt and we spray it directly on the test specimens, there's more to it but I'll spare everyone the details. What works best at fighting corrosion? Something that's been pickled (covered) in oil, no joke. Next best thing? Zinc phosphate over clean steel with good Ecoat plus a good OEM approved primer sealer, basecoat & clearcoat.

[malinator]

If you were going to put oil on the underside of the car, how much do you use and how often would you apply it? Also what type of oil?

[DerekTheGreat]

Depends who you ask but to me it doesn't really matter. I live close enough to Canada, which has places that offer up Krown rust proofing so I take my cars there to have it done. If I had to do it myself I'd just use the motor oil left over from oil changes, thin it out a bit with some mineral spirits and then spray that everywhere. Gear oil would probably be best but that's a bit too stinky for me.

Background info on Krown:

https://www.krown.com/process/

[GM_Guy]

This thread reminds me that I still need to check the hvac drain on my '08.

Alex.

[gadget73]

One of the good things where I live is we don't have annual inspections like I've heard others mention, so I don't have to worry about my car.

This is actually one of the very few places in life where I'm in favor of government meddling. It forces people to worry about their car. Not for their own sake. Don't take it the wrong way, but I could give a shit about the owner of the car. I don't want them hitting me because their car broke in half or had no brakes. Emissions, fuck it. A tailpipe is far less likely to cause me immediate harm than the bald tires and rotted brake lines are.

[HiFiMerc]

My '92 is rusted out in the same spots that Zach's was. Not as bad, but it's there. Still debating whether or not to have it fixed. The one on the bottom of the frame rail is easy, the one inside the frame is another story for me.

Bit off topic...but is there a way to re-route the HVAC drain so it doesn't subject the frame to a slow painful death?