Rust - under fender area

[skillinp]

I don't know what it's called, but the area behind where my fenders attach to the inside of the engine bay had some issues with rust. By issues I mean I took off the fender to do some preventative POR and found that there were holes straight through the metal. I'm grinding the rust off now with some wire brushes, but I'm not sure what I'm going to do about the repair.

I figure I have a couple of options:

I could cut out the old stuff (the leftover holy metal) weld some sheet metal together and try a (probably ghetto, but hidden) replacement. I'd probably leave a hole in it for water to get out in the future.

I could try filling in holes with epoxy (I have a pound or so from POR)

cut out old stuff and replace with just what is needed to mount the fender back on (minimalist, just something for the bolts to go into)

Find a place that sells this particular part and replace it that way??? I've looked around but am having trouble finding this specific piece

Cut one out of an old car in a junkyard or something? Except I'm guessing the same piece will have the same issue there, too.

I'm thinking of taking the pics to a body shop or the mechanic I trust, but I'm on sort of a small budget. As in starving college student budget.

For reference:

That's a '73 240z, though I'm guessing that the frame would be pretty much interchangeable with any other 240, 260 or 280.

Any thoughts or opinions would be appreciated, thanks!

Oh, and one more thing, there are two other spots with rust holes that I'm going to be dealing with at the same time as the above, one right below the gas cap's door and the other (the worst one) on the front part of the doorframe. I'm trying to figure out where the water came from that rusted out the area on the door frame, and it doesn't appear to be coming from the fender and moving back... could it be a bad seal on the windshield that's leaking water down into the frame?

Thanks

[esmit208]

SKILL

It can all be fixed. If you are any good with a welder and metal shaping or you are willing to pay a professional to fix it for you. If you don't do something though eventually it will rust completely through and fall off the car. The passenger side cancer is more than likely due to an unsecure battery and the original unsealed type of battery that was common when these cars fisrt hit the street. The unsealed battery emitted gas that rusted through everything on that side of the car including the firewall and floorboard.(See Project 3/72) In addition the area underneath the fenders was not treated with anything to prevent corrosion and these cars were shipped from Yokohama on top of ships getting a nice salt bath for the duration of the trip from Japan. Some cars had rust on them before they were even sold. But it CAN BE FIXED. It's up to you if you want it to be (probably ghetto, but hidden) , your words not mine. Project 3/72 WON'T be GHETTO and it will all be fixed with no future issues. If it turns out to be GHETTO that is probably where you live!

[EuroDat]

I agree with esmit. Its all fixable given your ability and/or budget. If you can't afford to repair it properly now than you really need to treat the rust to stop it getting worse.

The quick "getto" fix would be to treat the rust. Just giving it a coat of paint wont help. That will only hide while it keeps eating the car. You will need to wire brush it as much as possible and treat it with rust converter. Fill the holes to stop water getting in. This will slow it down a lot, but wont stop it completly.

You will need to do a propper cut and weld new metal fix in the future when budget permits.

[ZCurves]

You need to first deal with the rust. Go to a paint store and buy a gallon of Phosphoric Acid and thoroughly soak the rusty areas and let it dry. You do not have to be all fancy and complicated with the rust neutralization. Do what I said with the Phosphoric Acid before and AFTER welding in repair panels. This will set you up for POR and no more rust. You will also need to spray Phosphoric Acid up into the upper frame rails, lower frame rails and rocker panels - anywhere that is concealed. Follow with something like Eastwood's Heavy-Duty Anti-Rust or SEM rust prevention. DO NOT fill the holes with epoxy as this will just lead to further decay. I see you are in SOCAL or nearby, so you could start looking for a donor car in a junk yard that could yield the appropriate patch panels. Certainly you would be able to locate one in parts yard down towards LA or on this forum. Take your time and weld in correct patch panels for sound structural repair.

Have you looked over the rest of the Z for rust? In addition to the areas I mentioned above, have you looked at the floorboards, around the tail-lights and rear deck??? There may be more surprises! But I hope not.

[Carl Beck]

With that amount of RUST where it is - one has to wonder what the inside of the frame rails look like, or what is under the tar mats on the floorboards, Wonder how much RUST is in the rear dog legs and rear wheel arches.... I've dismantled a lot of 240Z's and haven't seen rust like that, in that area on any of them.

Hate to be pessimistic - - but the deeper you dig - you may find a lot more problems exist than you can afford to fix.

College Student Budget. Start saving your money and buy a far better condition example to begin with. Sell that car to someone that has the metal working skills necessary to fix it ... Don't throw good money after bad..

Just my opinion..

FWIW,

Carl B.

[ZCurves]

I second that!!

[EScanlon]

That's a nice Urban Legend about the Battery Acid Fumes causing all that rust.

Since it appears on BOTH sides, and in roughly the same amount, it's probably due to the weep holes having been sealed by an over zealous caulker at the assembly line. I've seen several cars with this problem and every one demonstrated the same glob of caulk stuffed into the weep hole at the very front of that channel.

The area you are looking at on both sides, is the upper side of the Fresh Air Vent and Front Body Frame Member. The Seam that stands straight up along it's length is where the outer edge and the upper edge were spot welded along it's length. Onto that seam is where the Inner Fender Rubber Seal gets mounted to avoid having the tire splash road water and grime into the engine bay.

At the very front of the join, where the outer sheet metal now begins to join the actual Inner Fender sheet metal there is a small gap, about 3/16" or 1/4" that allows any water that may have seeped, leaked or splashed onto the "V" channel that extends all the way to the under Cowl area to drain, sadly, INTO the engine bay. This often got caulked at the factory when they installed the outer fender, thereby PLUGGING that "V" channel so it could accumulate water, debris and eventually rust.

Then again, I've seen cars where you pull off a small nest of pine needles, lint and other debris that washed down from the cowl and eventually clogged the weep hole. This is very similar to what happens to the rust at the front edge of the rocker panel and the rear and bottom most edge of the outer fender.

The solution will depend on your time, experience and money.

Simplest, is to simply cut out the old metal, treat the Fresh Air Vent Tube for rust protection and then weld in new metal. While the inner seam is important for placing and mounting the outer fender to, the outer (the one with the curve) seam only supports the Inner Fender Seal. In other words, make sure you replicate the inner seam (and part of the inner fender) but don't worry too much about the outer seam.

As far as the rust on the "A" pillar, it's a long stretch for it to be part of the problem coming from the cowl area (and therefore related to the above mentioned rust), but it is plausible. Granted the car would have had to be stored at a 30° angle for the water to seep towards that back area. A more likely scenario has some gunk getting caught in the "Whale Tail" seal and being held in place.

To me, of the two problems you have, the second is probably the more worrisome. As others have mentioned, you're probably going to find a bunch of rust under the tar mat on the floor and probably the rockers as well.

FWIW

E

[Mikes Z car]

EScanlon,

That is a terrific explanation. I wonder if what might cause the kind of rust on the A pillar seen here could be from a poor seal between the windshield rubber and the metal of the car especially at the top near the roof? I have been thinking about prying up the rubber seals on my car and pushing into the resulting crack some of that black stuff used in windshield installs wiping excess off as a means of improving the seal.

Mike

[EScanlon]

Mike, that's as good an explanation as anything else.

However, just prying up the rubber to try to inject the black caulk adhesive might not fix the problem at all.

There are a few spots in the windshield frame where water could easily find it's way into the cowl and the A pillar, as well as in the upper corners. Simply injecting caulk/adhesive might only help channel the water to those openings.

Are you sure you have a windshield gasket leak problem? or are you addressing it in the preventive maintenance manner? If you DO have a problem, I'd recommend removing the windshield and examining the gasket and the opening before you try to stop gap the leak. If you're doing preventive maintenance, and the windshield was installed properly, I don't know that I'd do more than simply lift the outer edge and only squeezing enough sealant to help the gasket. Too much monkeying with the gasket could twist it and result in the problem you're trying to avoid.

FWIW

E

[skillinp]

Thanks for all the help guys, this is really helping!

There are some other spots of rust, but for the most part it's just surface stuff and I'm removing it right now with a wire brush. All of this is meant to be preventative, since I have to park my car outside for the first time since I bought it a year and some months ago. Parking garages are nice to have with an old car. Most of this stuff has been there for a long time, I'm guessing, but since my roommate usually has his car in the garage, I wanted to make sure the rust I have now doesn't get any worse than it already is, and reverse as much as I can while I can.

The whole car needs to be stripped and painted, and I want to do it right, but that might not be for maybe two years before I'll have saved up enough to do that, I just need this to hold out until then.

Since I have this going on anyway, I'm going to see if I can't poke around some more and see if there is anything else hidden like you mention. Hopefully not, but if it comes to it, my plan B is to find another car with less or no rust issues and transfer the parts I like or have already customized over; the newly installed l28, the nicer shocks, the fender mirrors, etc.

Again, thanks much for all the suggestions and help, I'll try to remember to come back and post results when I'm done with this bit of the project that is the z.

[skillinp]

That's a nice Urban Legend about the Battery Acid Fumes causing all that rust.

Since it appears on BOTH sides, and in roughly the same amount, it's probably due to the weep holes having been sealed by an over zealous caulker at the assembly line. I've seen several cars with this problem and every one demonstrated the same glob of caulk stuffed into the weep hole at the very front of that channel.

The area you are looking at on both sides, is the upper side of the Fresh Air Vent and Front Body Frame Member. The Seam that stands straight up along it's length is where the outer edge and the upper edge were spot welded along it's length. Onto that seam is where the Inner Fender Rubber Seal gets mounted to avoid having the tire splash road water and grime into the engine bay.

At the very front of the join, where the outer sheet metal now begins to join the actual Inner Fender sheet metal there is a small gap, about 3/16" or 1/4" that allows any water that may have seeped, leaked or splashed onto the "V" channel that extends all the way to the under Cowl area to drain, sadly, INTO the engine bay. This often got caulked at the factory when they installed the outer fender, thereby PLUGGING that "V" channel so it could accumulate water, debris and eventually rust.

Then again, I've seen cars where you pull off a small nest of pine needles, lint and other debris that washed down from the cowl and eventually clogged the weep hole. This is very similar to what happens to the rust at the front edge of the rocker panel and the rear and bottom most edge of the outer fender.

The solution will depend on your time, experience and money.

Simplest, is to simply cut out the old metal, treat the Fresh Air Vent Tube for rust protection and then weld in new metal. While the inner seam is important for placing and mounting the outer fender to, the outer (the one with the curve) seam only supports the Inner Fender Seal. In other words, make sure you replicate the inner seam (and part of the inner fender) but don't worry too much about the outer seam.

As far as the rust on the "A" pillar, it's a long stretch for it to be part of the problem coming from the cowl area (and therefore related to the above mentioned rust), but it is plausible. Granted the car would have had to be stored at a 30° angle for the water to seep towards that back area. A more likely scenario has some gunk getting caught in the "Whale Tail" seal and being held in place.

To me, of the two problems you have, the second is probably the more worrisome. As others have mentioned, you're probably going to find a bunch of rust under the tar mat on the floor and probably the rockers as well.

FWIW

E

Brief update: I checked out the drain areas at the front of the channel, you're right, it appears that they were blocked by some caulk or sealer or something, which would have pooled water in there an eventually rusted through. Like it has.

I've decided to take out the front windshield to try to trace the water source back to it's origin, it appears the seal was not very good and water was able to get in around the top there is also a spot on either side that looks like it would have allowed water in, so I'm going to get some new seals and really seal it in there.

Also, I've decided to weld new sheet metal into some of the areas where the water was pooling, but also to leave some open for better drainage. Then I'm going over it all with some anti rust paint like POR or something to that effect.

Again, thanks to everyone for all your great help!

[skillinp]

Another quick update: decided on and finished most of the following:

open everything I can up, take off as much as possible and find source of rust.

-it appears to be coming from the roof, so all new seals are now here

cut out worst of the rust and grind away at more. fill with epoxy or weld in metal depending on size. Bondo over that and sand down bondo to get smooth surface

lightly sand entire body and wrap in vinyl (I'm going with matte black)

-this will be cheaper than a good paint job, and will last until I can afford a good paint job

Everything is done now except for the wrapping, which is tricky, but will only take another day of solid work.

-this is taking so long because I'm working double shifts and just got on break from school, which meant finals and studying for them through last week.

I have pics of most of everything, not sure if anyone is interested to the level where I should post them. For the most part, I wanted to keep them as a record, but if anyone wants to see, I can post them here or link you to them on my dropbox folder.