Any fixes for rust in trunk lip?

[Phishy4]

Got some rust forming in the crease of the trunk lip on my e36 m3. From what I can see its not coming from the inside, but I could be wrong. Is there anything I can have done now to fix before it gets any worse? I'm not a body guy or anything, just hoping that I could get away with having someone possibly sand that back side and maybe touch it up to keep it from getting deeper.

Edit: trying to upload the pic from my phone, not sure it's working.

[Accumulator]

phishy4- Fixing rust in those areas is incredibly tough, and any truly permanent fixes are, IMO pure luck (and yeah, I have been lucky a few times). In your case, I'm sorry to say that IMO it's already too far gone. And yeah, it *is* coming from the "inside".

No matter how good your paint/body guy is, I'd get a replacement trunk lid instead of trying to fix that one.

[RaskyR1]

Hey...that tree looks familiar....

[Ron Ketcham]

That area is referred to as a hem flange and the corossion IS coming from the inside of the flange.
Would have to open the flange, remove any rust, apply an acid etch primer sealer, then paint.
To stop this in the future an ASTM 117B approved cavatity wax must be fogged inside the flange and all cavatities of the trunk.
Mazda has had huge problems with this and other areas on their vehicles, but Mazda Japan will not allow either Mazda US or Mazda Canada to address the concern.
Ford has ValuGard private label their cavitity wax (rust inhibitor-rust preventative-rust proofing) for al their body repairs and is required that it be applied by a bodyshop doing repairs on any vehicle still under warranty.
The lead body paint engineer for Mazda and I addressed the concern you have back in 2002 and using the ValuGard cavitity wax came up with a program to address the concern.
However, Japan said no, as it would have the possiblity of creating huge warranty costs if people were aware that there was a problem.
Go to ValuGard.net to see various Technical Service Bulletins, Repair Procedures by several vehicle manufacturers.
Grumpy

[Accumulator]

...Mazda has had huge problems with this and other areas on their vehicles, but Mazda Japan will not allow either Mazda US or Mazda Canada to address the concern....

Nor will they honor their corrosion-perforation warranty. Oh, just get me going on this one

[Ron Ketcham]

And welcome to world of the state's DOT's in the salt belt states and Canada to magniesum cloride.
You really should visit the Valugard.net site and read all the newest info on this chemical being used on the roads, and not just in the winter.
In Canada, they put it on gravel roads to keep the dust down.
This stuff is nasty, -nice sunny day, it's 85f. and a little rain comes through.
No problem, right, it's summer time, the roads are clear, there is no snow or ice, no salt trucks spreading or in the case of mag cloride-spraying.
Wrong, it reactivates with water and is corossive all year long.
Grumpy

[Phishy4]

Thanks for the info guys, appreciate it.

Ron - Do you think its worth having a body shop give it a try or should I just start looking for a replacement trunk? Do you think that if I took that to a "good" body shop (there are so many around here, and expensive isn't always good, Rasky know's to what I refer) they would know what to do (i.e. is what your talking about doing a fairly common practice?)

[Ron Ketcham]

The age of your Mazda, I would find a good lid from a salvage yard and have it painted.
I would make sure, if you are going to keep the car, that they apply the rust inhibitor into the cavatities of the trunk lid, and this is done after paint work is finished.
For a bodyshop to pull loose the flange (hope that it is not totally rusted through the flange) clean, apply acid etch/sealer primer, after refitting the flange, prep, sand, apply a base clear, expensive.
A good used lid for $200 would be less than the labor to repair yours. Then the paint process cost will vary by shops, but I would believe they can prep, paint and install the replacement for no more than another $200.
Application of the rust inhibitor, one that meets all specs and is the one that I-CAR recommends as well as Ford (by the way, the Chrysler MoPar rust inhibitor and undercoating is the same as the
Ford MotorCraft, made by ValuGard), should be aprox another $50 to $75.
If you are not going to keep the car for more than another year, just go the cheapest way you can and trade or sell it to some poor soul before things get bad.
The concern you have, if you were to closely inspect the bottom flanges on the doors, around the wheel openings, etc, is most likely going to be there, just not as bad yet.
Sorry, no easy way out of this for you.
Grumpy
PS. 3M's product, which most shops will tell you they will use, is not approved by most car companies, nor does it meet the spec's of the industry, so make sure they apply a product that is really going to protect and stop rust.

[Phishy4]

Ok, thanks Ron. It's actually a 98 BMW M3 Sedan (e36 body, and the deck lid is a weak spot on all of them I guess) with very low miles for its' age (like 75k) and in very good shape otherwise, so I definitely want to do what I can to preserve/restore it (it's my summer/fun car). Luckily, there are some Arctic Silver trunk lids floating around so I should be able to find something in good shape that matches without paint. Thanks again.

[Ron Ketcham]

Oh, sorry, that's a great car, and one worth taking care of and fixing correctly, when I saw M3, didn't even consider a Bimmer.
I would check the bottom of the doors, etc as I mentioned though, due to where you live.
Hope you read the information on the ValuGard website about the mag cloride.
People think that new cars are rust proof, but then they don't read their warranty closely, only hold in their mind what a salesman or brochure says, not the actual warranty for corrosion. (which says "for manufacturering defects")
As the information on the site says, from the trucking industry, just for them it's a $30 billion dollar a year problem.
Class 8 trucks are big, strong, heavy metal units and they are rusting away under the eyes of their owners.
Grumpy

[RaskyR1]

I still say you should get a carbon fiber one and paint it silver.

92-98 97 96 95 93 BMW E36 4dr CLS Style Carbon Fiber Trunk Hatch

Didn't this car come from Florida too???


Ron, back in the day people always said to squirt some heavy weight oil down in the seam to help slow the rusting down. Is there any truth to that?

[Ron Ketcham]

It might slow it down for a while, but not for long, which is why some companies that sell the "oil treatment for corrosion protection" in Canada have to have the customer come back every year or so for "retreatment", plus it collects dust and as the oil evaporates, there is a "breeding ground" for rust left behind, with no protection. (plus the mess that is created on the concrete when the car comes from the oil treatment)
A "quality cavatity wax" will last for 10 years or more with no retreatment required, and it does not evaporate, but creates a seal over the metal or painted metal that blocks moisture and air from creating corrosion.
Grumpy