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Rust Issues

Rust Locations

Aluminum Tailgate Corrosion

Rustproofing Products

Rust Locations.

For 700/900 series owners, here's where they can rot:

  1. Various Spots. [UK] Inside the boot, there is a sort of pocket, either side, presumably for carrying water/things etc. This can rot through to the outside world and totally disintegrate. The sill drainage holes get bunged up and the sills rot towards the front of the car (especially where the sill meets the bottom of the front wing). Right underneath where the transmission meets the motor, look to the left and right and you can see the chassis box sections or arms / runners or whatever you call them, they rot from the inside out due to plugged drainage holes probably. Next take up the carpet behind the brake/accelerator, look up a little and there is a seam on the lower bulkhead or firewall and that can rot splendidly. They also go on the inside of the roof where the sun roof slides back. Another nice place to hunt the rust is the A pillar, which can rust quite badly behind the chrome trim, which is, of course pop-riveted on so it is a bastard to put back once off. Apart from that they are not too bad. At least when they are welded up there is something to weld to, which is never the case with a British/French/Italian car. [Note: see comments in "Doors" for reputed seam rust in rear doors.] [DaveM] All the corners of all the box sections can rust: look closely for bubbled underseal in the corners. Look at the mounting points on the rear axle, as there
  2. Frame Rails at Strut Linkage [Tip from Stefan, Minnesota] A common place for our 700's to rust is where the strut linkage attaches to the frame rails of the car. I first investigated my '87 740 (Minnesota car with lots of salt) when I found lots of front suspension vibration. It is visible if you turn your wheel and look in the wheel well - the bracket that has 45 degree towards the rear of the car. at that point where it attaches to the frame - the car will rust from the inside out. Your only evidence will be a slightly bubbled undercoating. (as mine was) I took the initative to scrape off the undercoating to find a nice hole there. the more I picked, the more swiss-cheese like it got... As I scraped and peeled back the undercoating - I found a 5" long crack in the frame that was about 1/4" wide and was "spiderwebbing" away from the main crack. The frame was ready to literally rip apart on the next big bump I hit. Totally scary! A welder was able to weld up the crack & re-inforce the frame with cold-rolled steel plates. As I drove the car home - it was totally vibration free.
  3. Fender Guard Joints.[Chris Herbst, Chicago] A common area for rust on the 700 is where the inner fender guard meets the quarter panel. If the bolt isn't put in, or is loose, then the quarter panel vibrates at speed and scrapes the paint off of the joint area. Make sure the bolt in that area gets fastened properly, but don't seal it since it can trap moisture. [DaveM] There is a seam on the OUTSIDE of the wheel arch exposed to all the elements; water can force the seams apart from the outside. Look up into the wheel arch towards the windscreen and look at the seam which may have started lifting and allowing water into the footwells of the car. This applies to the rear footwells as well.
  4. Door Window Frames.[Herb Goltz, Ontario].I am seeing plenty of 940s that are rusting at the base of the door window frame on the inside (back edge of front doors above the beltline behind the glass, rear doors in the same place but in front of the glass). It starts in the rolled metal seam, but spreads widely. In some cases, this rust is actually bubbling through to the exterior. It is a strange place to rust. I have scraped mine out carefully and am planning on getting some POR-15 onto all those areas.[Northeastern US] With the rear door closed you cannot see the areas involved. If you consider the door closed, you can see the outside and the inside of the door, the inside with the trim on. When you open the door, please look at what would be called the side or the place where stickers get put, or the mate to the striker plate. Now the Volvo door is really made of 2 major parts. The main part of the door being the bulk of it, and a piece of metal which frames the window and provides the track for the window to be held in place when it is up. It is at the place where this metal frame joins the door where it is welded, and has some manufacturers putty put over it. Another description is to open the door and look at the ends right below the molding that fits below the window. You should see a weld seam there. I have seen cracking/or rust at just the ends of the door toward the rear of the car, and have seen cars that have cracking on both ends on all four doors usually. Poll results on Northeastern cars: >91 940 1 OK> 93 940 2 OK; >93 940 11 BAD; >94 940 2 BAD 1 OK
  5. Windshield Pinch Weld. The welded pinch weld seam beneath the windshield butyl sealant can rust if the paint is damaged when removing the old windshield. The FAQ section in Glass has suggested repairs.
  6. 940 Frame Rails/Firewall Seams This last weekend I went shopping for another 945. I saw a nice one, a 94 but was shocked to see RUST on it. So I checked my 94 945 and it had the same rust in the same place. Open hood, look inside on passenger side right where all the brake lines get channeled together heading back to the rear. There is a seam/junction of metals and it was rusting all along there!!!!! Geeeesh, at least my 240's waited 8-9 years before they started to show rust. A sample of 2 isn't great, so check it out. [Tip from Ed Kuczynski ] Just bought another 94 945. And while researching found a weakness in the 945's. Look for rust on the firewall in the engine bay, passenger side mainly, along a seam thats fairly low on the firewall. I've seen SEVERAL that have light rust coming from the seams. Also in the engine compartment, again mainly on the passenger side, on the horizontal "frame" members where 2 pieces of metal form a joint. Out of about a dozen 93-95's, most of them had this problem.
  7. Fuel Sender Assembly Top. [Editor] While the tank itself is plastic, the fuel sender assembly top is steel and is so designed and located that it will definitely rust. See the FAQ notes on preventing this when you remove this unit to replace a fuel pump or hose. A replacement assembly is over $350.
  8. Oil Pan. [Editor] Salt Belt cars may see rusting oil pans: the outer surface rusts and perforates. You can repair by sanding, then applying JBWeld epoxy and a top coat of silicone or new paint. You can also replace the oil pan with a new unit.

Water Leak Areas. See Water Leaks in the Body: Glass file for more information about areas prone to leakage.

Aluminum Tailgate Corrosion.

[Inquiry:] No rust on the 88 745 but the rear tailgate has a small area of bubbled paint around door latch. looks like aluminum tailgate is pitted under the paint. I know aluminum doesn't rust but not sure how to refinish AL? Anyone have suggestions on how to refinish aluminum tailgate and repaint the area?

[Response: MikeH] Go to your local auto paint supply house; I used a local chain store called Mateus. Found them in the yellow pages. There is a special, self etching primer made for aluminum. They should know what I'm talking about, if they don't, go to another store. Sand the corrosion to bare metal, clean, prime with the self etching primer and paint. It's been awhile since I have done any painting ie years, but I still had my spray gun. I used lacquor since this was a driveway paint booth and I wanted something that would dry fast before the bugs and other trash settled on the paint. I ended up sanding with fine paper to get the runs and orange peal out but I finally got it right after several tries. They even got very close to matching the silver paint from the paint code!

Rustproofing Products. [Tips from Dave Gayman]

As a non-welder, I've put together a stable of substances for beating rust. I'll throw this out to the group for additions, edits, diatribes, etc. I don't have any financial interest in any of the brands, worse luck.

2-part solutions:

  • epoxy (any brand, any type except 5-minute, which isn't really strong or waterproof; I prefer marine type at any good boat accessory supplier; silica dust [thickener] can be added to make putty-like goo)

1-part solutions:

  • POR-15 paint (; great stuff, takes hours of preparation and dousing with POR's Metal-Ready [zinc sulfate, I think], makes up for lost sheetmetal when you soak fiberglass mat or cloth with it; cures to tough, pliable surface)
  • Corrosion-X regular (; consistency of salad oil, doubles as very effective penetrating oil; doesn't evaporate)
  • Corrosion-X heavy duty: consistency of thin mayonnaise)
  • Corrosion-X MaxWax: dries to soft, pliable wax; eventually wears off when used externally, but is good substitute for POR-15 when you can't reach areas for thorough preparation
  • NOTE: I order my Corrosion-X stuff on the East coast through: Bill Brown,, 1-888-746-5679
  • Waxoyl Underbody Protector (in the US:; black, strong-smelling mix of solvent, wax, and bitumen [tar] with consistency of pancake syrup; the Brits -- MG, Rover, Triumph owners -- love this stuff; eventually wears off)
  • PL polyurethane roof & flashing sealant (; available at Home Depot; fantastic stuff for gunk-plugging leaky seams, but takes a week or more to fully cure; I doubt this stuff will wear off)
  • Polyurethane expanding foam (Home Depot; don't get latex-based type; in one application, this appeared to be slightly susceptible to water, a problem; nice for backing Bondo stuff where gaps and holes would result in several pounds of Bondo inches thick; tender surface, must be finished)
  • RTV -- life without silicone seals and adhesives would not be worth living -- GE Silicone II appears not to give off acetic acid during cure, but I don't know that for sure.

To avoid:

  • Ultraviolet-curing Bondo (probably operator error on my part, but seems too thin, and it definitely cannot be applied except in the dark -- any sunlight during application results in scummy, knobby surface)

For POR rust proofing products, check out

Ziebart-Like Spray Application Rust proofs:

[Other Tips:] The Rust-Check Product (only in Canada) is excellent. I recall seeing a promotion recently to have a car done in Toronto for $99. I don't know the exact contents, but it is an oil-type substance that they squirt into the un-seen panels of the car. Holes are drilled in strategic locations, and later filled with rubber/plastic plugs to make this possible. Be prepare for the car exterior to be a bit drippy/greasy for a few days after you get it back from the treatment. Just park it on the lawn instead of in the driveway for few days. [Does not trap moisture like solidifying treatments like Ziebart.]

[Editor:] Much controversy among Canadians on the BBS seems to favor Krown over Rust Check for reasons of quality.

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