On a few of the 4-runners I looked at, all are forming a fair amount of rust under the moonroof weather stripping (the piece around the glass) Pull up the edge and check it out, on a truck with basically no rust, this place was still rusted pretty bad.

So you're saying the frame around the glass is rusting? Where -- front, back, sides?

Yes, its the frame around the glass (that moves with the glass)

I don't know if it rusts on the sides (haven't figured out how to remove the weather stripping completely).

Just open your sunroof, then push up on the weather stripping a little and I bet you will see the rust.

Check the underbelly behind the spare tire. There, you'll see plenty of rust around the differential too.

I looked under my 98 honda also out of curiousity, and the suspension system is painted so there's no rust.

I clean and wax in and around the sunroof about 2-3 times per year.

Also check the holes behind the rear plate where it screws on.

Massive salt where I am............ disgusting !!!!

Guys i'm just saying check, you cannot see this unless you push up the weatherstripping. There is flaking rust on a 2006 (66k) that has just tiny bit of surface rust on the frame (very close to like new condition), the 2003 with 90k had much more severe rot on the sunroof.
I suspect most have just not thought to push up that weather stripping to check, i don't care how well you clean up there, this is not a drain clog issue.
I am going to see if i can remove the stripping all the way around, remove the rust thats on there, put some rust converter, and then fill the weather stripping with a grease where it contacts this lip.

Sorry to bump a dead thread. I just bought my 07 4Runner and as I was cleaning it today, I noticed some rust under the weather stripping.

Has anybody actually removed the weatherstripping to clean and reseal it?

Are you guys sure it's rust? Or is it rust dust?

They have a strong tendency to rust here.
I tried to remove the weatherstripping. Doesn't look possible without removing the headliner, which is a huge pain in the ass.

It's definitely rust...take a look (sorry for the pic size). Do you think this would be covered under the corrosion warranty?

My interpretation of the warranty on corrosion would be no, because I inquired about it with Toyota before in regards to the metal bumper on my 1990 truck. Toyota says it's only on the body sheet metal only and it has to rust through completely (rust perforation).

However, I would still take it to Toyota, worst they can say is no. I had the rear bumper on my '05 Tacoma replaced after three months when there was rust on it. The service writer said, I needed to take it up with the service manager and he would make the call. He wasn't there, I wrote him a letter with photos (to avoid making multiple trips to the dealer to find him) and said, this isn't what I expected from a Toyota product, let alone a three month old truck. They called back and agreed replace the bumper.

What year is your 4Runner? I'll have to take a look at mine.

Mine is an 07 SE with about 43k miles.

I was a little shocked to find it considering I don't live near the beach or where salt is used on the roads. It looks like the water may be coming in from the top of the weatherstripping.

UPDATE: I had a chance to stop by the dealer yesterday afternoon to see if this would be covered under the corrosion warranty, they told me no (big shocker).

I'm going to try calling Toyota corporate today to see if I can get this covered.

I find it hard to believe that they wouldn't cover corrosion on the moonroof under the corrosion warranty.

UPDATE: I got a response from Toyota. it looks like the customer relationship manager should be calling me next week so we'll see what happens.

Thank you for contacting Toyota Motor Sales.

We are sorry to learn of the concern with your 2007 4 Runner moon roof.

Please be aware that Toyota relies primarily on the dealerships to assess if a concern qualifies for warranty coverage.Though you state you have already spoken with the service department, we have contacted the Customer Relations Manager to ascertain the dealership's position and determine if any further avenues exist at the dealership level. The Customer Relations Manager will contact you by the end of the business day, October 14, 2009.