[Wolfgang Huang]

I have seen the rust for a few years but never paid much attention until this morning. I think it's getting worse than I thought and almost rusted through (attached photos). I wonder if there is any way to seal the area to stop or at least slow down further rust. The alternative is of course to have it properly fixed at a body shop. Surprisingly, the other side is perfectly fine with no hint of rust.

 

[MuranoSL2003]

Wow, that is pretty bad!

My '03 also had rust in the same place, but barely visible when I traded it last year due to the front frame suspension member rusting almost completely away due to AC condensate dripping in it...

Your rust area has been mentioned a few times over the years. Usually there's a lot more rust that you can't see... I don't think there's a way of stabilizing what you're experiencing without cutting it out, seeing what's behind it, and welding in new metal...

 

[BurtReynoldsWig]

I'm sure that's the right way to deal with it. I have a smiling. Amount of rust on my wifes Honda. I waited until it had dried out well, gave it a good clean with a wire brush, added a Waxoyl-type product to the underside and brushed on Loctite Rust Preventer - other products are available - on the painted side. The rust has stabilised and has not spread beyond it's original area. Depending on your abilities and needs, this was a quick, simple and so far effective way of dealing with it. Some will come on now and say that the rust will be continuing unopposed, etc. And that is a possibility, but visually it is as it was 2.5 years ago. All the best.

 

[I need coffee]

The ideal thing to do is to remove the rust completely down to bare metal and cut out the really bad sections if necessary (which would require some welding to repair). Given the age of the car, this probably wouldn't be economically feasible unless you could do it all yourself. One other option is to remove the rust as best you can and use a rust converter which oxidizes whatever you missed and dries to a paintable surface. Rust-Oleum makes a variant called Rust Reformer and there are many others. If done well, such a repair should easily buy you a couple of more years at least. First try to find out exactly how bad it's gotten, especially the areas you can't see without removing panels etc. Good luck and let us know what you decide to do.

 

[Wolfgang Huang]

Thank all for the replies. I will look into the possibility of DIY using the rust inhibitor. I haven't done body work and have no welding equipment. I may take it to a body shop for a rough estimate to see how much it would cost. If it's $500-600, I may consider it but I doubt it. The car is still in good shape with 148k miles, but with the unpredictable CVT, I don't feel like to spend a lot of money on it.

 

[gmadigyal]

@ Wolfgang Huang - The rust you are experiencing is not new or unique to your MO. It has been reported by many others in this forum as eluded by
MuranoSL2003. The rust is most likely due to moisture retention behind the panel beading seal. The only way to get rid of it completely is by removing the panel and replacing any badly rusted and pitted metal with clean metal (welding) and repainting with rust proof primer first before applying the final color coat... You may be looking at a significant labour cost which may not be justified for a aged car with unpredictable CVT. Good thing is it is not a critical part which can result in any major accident if it fails...Also it is not visible when you close the door. so it is only a hidden cosmetic issue at this time..I wiould accept this and adapt to live with this rust 🙂

 

[MuranoSL2003]

If you decide to live with it, maybe some white duct tape or similar will help a little with the cosmetics.

 

[Wolfgang Huang]

If can I get the rust inhibitor/remover/reformer to work, I will try to live with it. It's not cosmetically offending since it's hidden behind the door. I have not done anything yet. Will report back when I have.

 

[Wolfgang Huang]

I posted this thread almost 3 years ago, and I finally did something to the rust. It hasn't gotten much worse since I have not driven on salted roads much, and when I did, I tried to wash the salt away ASAP. What I just did was to use Rust-Oleum Rust Dissolver to dissolve and "wash" the rust away, then spray the 2-in-1 Rust Reform & Seal. Finally, I used two-part PC-7 to coat and fill the area, and hopefully, this will further shield the area from the elements. I only took the final picture.

 

[MuranoSL2003]

Unfortunately, I think the origin of the rust is on the other side of your patch due to the way it's constructed... At least that was how it looked to me when I started seeing the surface rust on my '03 after 16 years. Luckily it seems a very slow area to rust, it didn't appear aggressive at all...

The front subframe rust on my '03 was super aggressive, and ended our relationship... I think the front subframe rusting only occurred to a few '03 Muranos, I haven't heard very many reports of it for other model years.

I would recommend carefully inspecting the front and rear subframes for rust. Rear subframe rust is more common for 1st gen Muranos from what I have seen...

 

[Wolfgang Huang]

You are right, the rust exists on both sides. When the rust started, it was only visible the top side, but now, it went through along the edge. I did the treatment and patch on the top side and the underside in the wheel well. There may be more rust in-between that I cannot get to without removing the interior panels.
I am aware of the subframe rust problem on 1st gen, especially on 2003 and 2007 models for some reason. My 2002 Maxima had rust problem on a structural beam supporting radiator and engine, and I had to junk the car. I do pay attention to those areas when I wash the car or when I am underneath it. So far, it doesn't look bad. When the weather gets better, I will apply the rust reform/sealer on any spots that look rusted to hopefully prolong the life.

 

[MuranoSL2003]

This is what my front subframe rusting looked like:

Severe front crossmember rust

I have seen many reports of severely rusted rear sub-frame members, but haven't found any reports about severe front sub-frame cross-member rust like I just discovered on my 2003(called front suspension member, FSM FSU-7). I noticed some rust on the front passenger side of the front cross-member...

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