I bought a 1988 XJ with some mold issues. It’s pretty clear of rust though (it had spent most of its life in Florida before being brought up to the northeast a couple years ago.) But now that it’s in the north I figure I’ll have to do a rust preventative treatment. Because of the mold issue, I’m leaning toward ripping out the carpets. But from there I’m not sure how to proceed.

I found an article that talked about one solution: using Herculiner on the cab interior, covering over the Herculiner with Dynamat, and then covering that over again with Herculiner. I’ve never done this before but I’m willing to try, but a few concerns. Herculiner states that you should do 2 layers. If I went this route, should I do 2 layers of Herculiner as a base, followed by Dynamat, and then another Herculiner layer/something else to cover over the Dynamat?

Also, I’m planning on buying a new, replacement carpet for my Jeep (from Stock Interiors.) They claim to cut to size and that it fits the Cherokee perfectly. But would all those layers of material underneath throw off the fit of the new carpet? As in, would it stick up too far and not be able to tuck in correctly?

Stock Interiors also sells a “mass backing” which it claims is a “Great heat and sound barrier added to back of carpet.” I’ve heard older Cherokees get hot underneath, but would I be better off with maybe 2 layers of Herculiner/Por-15/ similar, then just a carpet with mass backing? I’d think it would fit better into where it needs to tuck in. But I did like the idea of a quieter ride with Dynamat. Also I called Stock Interiors to try to get more info about the mass backing and the salesman was useless, he just spoke in vague generalities and from what I understood basically told me I didn’t need it. I asked how good the mass backing was and all he said was that he couldn’t give me a specific R value.

Any help would be appreciated especially if you have experience with this issue.

Article I referenced:
https://www.motortrend.com/how-to/154-0608-august-2006-jeep-cooling-kits/amp/

 

You do you but here is what I found when doing mine.

No rust or mold. I pulled the carpet out and cleaned it out of the vehicle. Got it looking good except for the cargo area piece. I'm replacing that with the non-mass backing carpet. I have it laying out in my family room to get rid of the wrinkles before I install it. It's just like the factory piece except, yes, I will need to trim it as it comes oversize. I have the original as a template or I may just fit it in place and cut as needed. Haven't decided yet.

After I got the carpet out, I cleaned the floors with soap and water. I scuffed up the paint in preparation for Herculiner. After the scuffing, I wiped everything down with denatured alcohol. I applied two coats of Herculiner per the directions. Turned out nice. I did notice that painting the Herculiner over the factory "dynamat" did not adhere well. I would guess you will have similar issues if you try to apply the Herculiner over Dynamat.

After the Herculiner dried, I did apply some Kilmat. I didn't do the whole floor like some people do. I covered about 25% of the floor and did areas that I thought would transmit unwanted sound(larger flat areas mostly). I had my door panels off at the same time so I put some Kilmat in those also. Again, not trying to cover the inside 100%, but enough to take the tininess out of them.

It made a difference.

In the cargo area I will add a little more Kilmat, probably closer to 75% coverage. Partly because there are large flat areas back there and partly because I still have quite a bit and it doesn't do any good sitting around in a box taking up space in my garage.

 

Ok just to clarify, when you scuffed up the floor to prep for Herculiner, did you leave the factory “Dynamat” in place and scuff around it? Or did you remove, scuff underneath, replace Dynamat, and then Herculiner over that?

I guess I just pictured myself doing this by stripping the floor of everything, doing 2 coats of Herculiner, cutting to size and putting in new Dynamat pieces, and then covering over the dynamat with a layer of something, as that magazine article said that covering over the dynamat with a layer of something would help prevent pooling. But maybe dynamat wouldn’t be the right product to cover it over with. I’ll have to look around for what might be a good product to cover the dynamat with.

Also, how difficult is it to remove the carpet without destroying it? The videos I’ve watched mostly show people cutting and destroying them. I’d think it would be difficult to remove in good enough condition to reinstall.

 

I did leave the factory stuff in place. I scuffed it up a bit also.

Do you plan on putting carpet back in? If so, I can't see a solid reason to cover up the dynamat with something other than the carpet. That's what I did.

Removing the carpet was not overly difficult. It took some awkward handling to wrestle it up over the center hump with all shifter/brake lever, etc.but I got it out in one piece. I laid it out on my driveway and scrubbed it several times and then let it dry in the sun.

I don't have an "after" pic(forgot to take it) but below is the "before" pic. All of that crap came out.

 

Ok I’ll try to be careful with the carpet when I remove it, it’s not in awful shape so I might just be able to scrub it and vacuum it and put it back. I’ll have to see how it looks and decide whether to put it back in or order a new one. Luckily I’m in no rush to get the Jeep on the road.

I think you’re right about not covering over the dynamat with Herculiner, I’ll just do 2 coats on the floor, followed by new dynamat and then a carpet without mass backing. I’m not even going to start this project until next weekend or 2 weekends, I just want to gather all the supplies I need now so I can jump in later. I’ll update and add photos when I get started.

Thanks for the help!