Unless the car has safety problems the fix is simple. Now this fix isn't going to make the underside of the car pretty but it will stop rust in its tracks. Wash the car to remove all salt - I'm talking a trip to the local coin operated car wash - almost no cost. Put the car up on stands and soak the underside with you choice of rust preventative oil. For this you need an air compressor and some sort of spray gun. This stuff will creep into seams, cavities and joints you will never reach with a sander or paint. Figure on having to repeat this process once a year. Observe all safety precautions. Done.

 

I have rust in most the same spots on my car. I was quoted about ~$3000 from a body shop to do the job. They did another EvoM member's car and they were telling me about the top of the gas tank being an issue as well.

My car is currently up on stands because I need to install a new oil pan and ship my trans to TRE. I hope to have the subframe out in the next couple of weeks (I dont get to work on the car that often right now) and Ill update this thread and some others with pictures once I am done with the rust removal.

The worst part for me is that most of my car is coated but it thins out towards the back and then by the subframe there is none so thats where most the rust is on the car . I wish you the best of luck with your car!

 

Last weekend I wasn't able to do much because of how cold it was and all the snow. However this weekend it is nice and warm! I will be taking a needle scaler to all the rusty parts and apply POR15 to everything that is affected. Any areas that the scaler can't do will be wirewheel'd.

I took a video of the rust I am working with.


If this saves the rear of the car, then fantastic. I will continue to monitor over the years to come.
If it only slows down the rust and continues to slowly go bad, then I will likely purchase the entire floorboard (this said part here https://www.mitsubishipartscentral.c...r-pan-mn150936) and be done with it. However after a lot of research POR15 should do the trick with proper application.

 

I really think barneyb is on the right track ... "soak the underside with you choice of rust preventative oil. For this you need an air compressor and some sort of spray gun. This stuff will creep into seams, cavities and joints you will never reach with a sander or paint. Figure on having to repeat this process once a year"

There's just no way to grind all the bad stuff away ... period. How can you get to the inside of the rails, etc? Even if you got 95% of it (which I think is optimistic), it'll just start forming again and get back right where you are at now.

However using rust preventative oil will creep into all the nooks and crannies that you can't reach. Again, it'll have to be repeated, but I'm guessing that will be more effective than POR15, etc. Again, that stuff works great if you can get ALL the rust off.

I've been using a can of Boeshield on all the untreated areas of my Evo's underside for the past few years (one can every fall), and it appears to be keeping rust at bay. In hindsight, I wish I did this from day one.

 

What brand/name rust preventative oil is it that I should get?

The main problem is I really dont have access to a place where I can spray all that stuff for a long while. Rather then wait and let it rot I really want to start doing what I can. Letting the rust sit there and rot away more cant be better then not putting some POR15 on the cleaned up areas. I wont be able to tackle everything but I will try as hard as I can. Maybe the places that I cant tackle, I can figure out about this preventative oil you are talking about? I just need to know more about the stuff

 

The way I see it is twofold. Grind down to bare metal any place you can and then coat it with some form of paint. POR15 should work great in that application and offer a little more durability over a basic paint. However, as the same time as the name suggests its intended to be Painted Over Rust, so areas that are currently rusty with good metal underneath in theory the POR should be able to convert the rust and stop it from spreading.

While this is all great, as was mentioned by a few folks its not realistic to grid away all the rust or even coat all the areas that could be rust prone as there are plenty of nooks where no way a paint will be thin enough to creep into and spread. Given that I think the next logical way to go about it is to then spray some form of oil in those areas and hope that curtails the spreading of anymore rust. But as mentioned while something like POR should be a permanent fix the oil is something that needs to be kept up with.

The only rust preventative oil I have experience with is Fluid Film and while it works it fairly expensive. Im curious what other products folks on here have used with success.

One other thing to keep in mind and I can't stress this enough- there are a ton of products on the market that are horrible. A lot of those underbody ruberized coatings do nothing other than trap in the moisture and then eventually flake off.

 

Not able to do it yourself? Then go here........
https://www.krown.com/en/locations/

 

Any Evo owner who drives their car in the winter should undercoat it, no question. Krown is a good option.
I've already seen an Evo X with 80,000 miles that was too far gone to fix. The whole undercarriage was totally rotten, and there was considerable rust on the rear doors and trunklid. It was a parts car within 10 years on normal use. It could have been perfectly fine if the owner had taken care of it.

 

I feel your pain. I have to remove my rear windshield to fix a rust right on the edge. And I have leak behind my dashboard which seems to be common problem with my year evo and lancers.

 

I did some sanding today with a wire brush and I have to agree with this based on BarneyB's recommendation. Unfortunately I do not have an actual lift so I will have to go to a friend's and do it there. Using an air compressor and drill with a wire brush is also helpful. With the car on the ground and only on ground jacks, I was only able to get in some spots in the subframe. My car has very little but it is there and I am **** so I want to treat all of it.

I used Corroseal and found it is pretty effective. It is also fairly cheap. A 1 gallon jug costs $53 on Amazon. $34 for the quart size. The beauty of this product is once you have a rusted base you just dab it on with a paint brush and go to town on all of the areas you hit with the compressed air, sand or drill.

 

Hello my fellow evo family. I have some bad news. I have been working nonstop all of last weekend trying to get away at all the rust. But it seems the rust is too far in, and has penetrated a lot of both sidemembers.


At this point it seems the car as doomed. The more I keep going at it, it eventually just makes a hole. I am unsure of what to do, as I do not want to give up on the car. Many tell me the sidemembers can be replaced, but labor I would imagine to be expensive as spot welds need to be removed and rewelded with the new piece. Also have had suggestions of buying a rear clip too. It is such a shame too because the rest of the car is perfect.

While I was able to apply some POR15 with a brush in the effected areas, my game plan is to apply another coat of POR15 via spray gun to ensure maximum coverage. If affected areas are covered in POR15 properly, this should buy me time for about a year or so. Hopefully allowing me to either buy a evo that was crashed in the front, or source the sidemembers I need from elsewhere when I can afford to have the work done properly.

Rust is the one thing that is pissing me off so badly at this point. It's not fair. I do not want to give up on this car.

 

Im sorry to hear that. I wish you the best of luck

 

it does not hurt to speak to a shop that specializes in rust treatment on cars. I think I would try to find the most qualified place and at least see what they quote you and get an opinion from them before you give up on the car. Like the shop that someone mentioned earlier in the thread.

 

 

like this place... they are nearby too

http://www.ziebart.com/auto-care-ser...ust-protection