The fantastical rear wheel well rot thread

[kjmclark]

The rear wheel well rust is just an outside result of rust further in. The problem starts because the outer wall of the rear strut tower rusts through. That lets tire spray run inside the quarter panel. It puddles at the rear corner of the wheel well and you get the rust through you see.

 

You have to fix the problem in the strut tower before you try fixing the rear wheel well rot, or it will just come right back.

 

He's right, but people miss it because it's not actually part of the strut tower. It's actually a separate panel that's next to the strut tower.

 

Here's what you see with the tire off, looking up:

 

Notice that there's a little discoloration, but no apparent problem. The strut tower looks fine. Keep looking:

 

I had to put the camera right above the brake drum to get this picture. Still looks OK, kind of, but there's something going on at the left of the picture, up at the top of the strut tower.

 

Here's what's going on:

 

I had to put the camera between the strut springs to get this picture. See the gray primer? You're not supposed to see that. It's on the inside of the quarter panel. There's supposed to be a metal panel here that's painted with the same undercoat as the other pictures. You don't see it because it's rusted out. How big is that rusted out hole? After I finished breaking out all the loose rust, I get a hole that's just over 8" wide at the widest, and about 4" high at the highest point.

 

Here's the template I made of the hole:

(All pictures hosted at http://www.flickr.com)

 

Until you patch this hole, you're wasting your time going after rust on the back of the wheel well or down in the running boards. This hole is causing the others.

[kjmclark]

One more note. These pictures are of the driver-side wheel well. The passenger side has the same problem, along with lots of issues on and around the gas filler neck tube. The template is reversed compared to the last picture of the hole. The biggest part of the hole is toward the front of the car, and the hole tapers toward the back of the car. The holes on both sides are symmetrical, so once you've got your template for one side, the other side is just the same thing, but flipped (again, bigger part of the hole toward the front of the car.)

 

Actually, I made a pdf of the template on graph paper. I'll have to find a way to post a link to it.

[WoodsWagon]

Thank you for taking good pictures of the strut tower rust I was talking about. Out of all the 95-99 subaru's I have checked in the junkyard, none of them had solid sheetmetal left. Half of them it was totally gone, the other half crumbled when I reached up in and poked it.

[Ricearu]

i'm hoping to get a new cordless cutoff tool for christmas or tax time. I am gonna start cutting out patch panels for real. I forgot about this post!

 

Thanks for the pic!, my legacy is kinda iffy there, I am gonna pour some phosphoric acid in there and seal that hole before my rear quarters go to hell too!

 

Only saving grace is that in texas, we don't get salt because snow and ice (if we even get it) never stays long enough to need melting, so they just find the slippery spots and run a sand spreader over em.

[Ricearu]

i'm hoping to get a new cordless cutoff tool for christmas or tax time. I am gonna start cutting out patch panels for real. I forgot about this post!

 

Thanks for the pic!, my legacy is kinda iffy there, I am gonna pour some phosphoric acid in there and seal that hole before my rear quarters go to hell too!

 

Only saving grace is that in texas, we don't get salt because snow and ice (if we even get it) never stays long enough to need melting, so they just find the slippery spots and run a sand spreader over em.

[kjmclark]

Thank you for taking good pictures of the strut tower rust I was talking about.

 

No problem. When "lmdew" wrote that his strut towers looked fine, I thought, "Geez, what we need here are some pictures. Well, duh, I could probably take some, and then maybe other people could catch this problem before their back-ends start rusting out." My little Christmas present to my fellow Subaru owners!

[idosubaru]

I am gonna start cutting out patch panels for real.

you cut all of them you can find and i'll sell them up here for you. LOL

 

kidding aside - cut me a few, we need 'em!

[axzon]

My question is: where/how would you apply this patch? Would it necessitate removing the strut? Access from inside? Weld it (probably)? Would a sleeve with a top and seal be as good (placed inside the strut tower and epoxied to the inside of the tower?

 

My 2001 Subaru Outback has developed cancer -- it looks terminal -- since it has spread from bubbling to about ten inch swath from the right rear door panel, past the filler, and heading towards the rear. Really rusted - some holes. Was going to try the West System repair but I'm wondering whether it's worth it. Car has 360k on it, but it's our only vehicle, and we need it to last just one more year.

 

Ideas -- suggestions.

 

Btw, I love the Subaru, but I hate rust repairs. I must admit Subaru is 1st Class in this department. Best/quickest rustout I've ever experienced.

[mikec03]

 

 

Car has 360k on it, but it's our only vehicle, and we need it to last just one more year

.

I was wondering when I read your comment if you were just trolling.  The effort to repair the rust area, even if successful, would not be worth the time if you are only concerned about one year of driving.  In any case, thanks for bringing the old post back to life.  I will lock under my 95 and 97 and see if there are holes next to the rear struts.  If there is, I will just plaster it with undercoating asphalt.

[axzon]

 

.

I was wondering when I read your comment if you were just trolling.  The effort to repair the rust area, even if successful, would not be worth the time if you are only concerned about one year of driving.  In any case, thanks for bringing the old post back to life.  I will lock under my 95 and 97 and see if there are holes next to the rear struts.  If there is, I will just plaster it with undercoating asphalt.

 

Nope, not a troll. Just preparing to repair yet another vehicle.

 

"...if there are holes next to the rear struts. If there is, I will just plaster it with undercoating asphalt."

 

I did that with one of my Suburbans years ago only  to told (after I had finished the job, of course) that the stuff is hydroscopic (i.e. likes water). Not pretty, but did the job alright. I'm also thinking of using low-expansion foam if the hole is as big as the article suggests -- thought on this?

 

Now, do you jam the stuff UP the strut tower or where? I haven't a clear idea what to do. I will use the West System to epoxy/fiberglass the rusted out areas over the wheel wells just for cosmetics. In the last while I've spent some big bucks (winter tires and stuff), so I'd like to get at least another year even if it costs about $400 to do the job.

 

Man, is this one rust-bucket: rusted through -- both wheel wells, driver's side roof between front/back, and on the hood (?!?) in three places. They must have warehoused this Subaru either in Halifax or Vancouver with the nice salt air to 'condition' the car for later years.

 

Thanks for responding -- this is an old thread, and my first post.

Edited April 18, 2015 by axzon

[npaine12]

+1 for west system and fiberglass. Fiberglass doesn't rust. I just molded a panel of fiberglass against what was left of the original metal to get the shape right, cut out a big hole until I found shiny stuff, glassed in my panel and bondo'd over the top to make it look smooth. Quick and will never rust again.

[axzon]

+1 for west system and fiberglass. Fiberglass doesn't rust. I just molded a panel of fiberglass against what was left of the original metal to get the shape right, cut out a big hole until I found shiny stuff, glassed in my panel and bondo'd over the top to make it look smooth. Quick and will never rust again.

Ahhh . . . just what I wanted to hear!

 

Questions:

 

1. Did you prep the bare metal with anything?

2. What kind of spray paint adheres to fiberglass/epoxy stuff? Can I simply auto-body canned spray paint over it? Do I have to prep the glassed stuff?

 

Thanks

[WoodsWagon]

2000+ Legacy's and Outbacks have a completely different rear suspension design, so the massive body rot issues those cars have are a separate issue from what this thread discusses. But before you put too much time into fiberglassing the wheel well rust, check out the rear subframe that the suspension and differential attach to. Those are well known for crumbling, and that's a serious safety issue. You can ignore the wheel arch rot, but if the crossmember breaks you'll likely lose control of the car.

[axzon]

2000+ Legacy's and Outbacks have a completely different rear suspension design, so the massive body rot issues those cars have are a separate issue from what this thread discusses. But before you put too much time into fiberglassing the wheel well rust, check out the rear subframe that the suspension and differential attach to. Those are well known for crumbling, and that's a serious safety issue. You can ignore the wheel arch rot, but if the crossmember breaks you'll likely lose control of the car.

 

 

Oh gee, that's great news. So, I checked it. It's still intact and clean. But just to be on the safe side, I'll paint it with RustBullet and prevent rust from getting a hold there. Fantastic stuff - it expels moisture, dehydrates rust, then bonds it to the metal. The comparison with other rust products is very enlightening. I'm just at the point of ordering materials, and I'm glad I read your reply. Be a bummer to do it all and find out later that the rear-end is crumbling. Thanks!