[Oldav8tor]

I took my Trailhawk to the Krown dealer in Lexington, MI, to have it rustproofed. While on the lift I inspected the underside. As others reported earlier, I found a mix of plugged holes and open ones. I also noticed areas where a rubberized undercoating had been applied and other spots where it looked like it should have been. At least everything was painted and the Krown process, while not an undercoating, does spray a penetrating oil into all channels, nooks and crannies. Since Krown is reapplied on an annual basis I will at least have a chance to keep track of what is happening on the underside of the Jeep.

The Krown guy was impressed by the design and robustness of the suspension and running gear. I was generally pleased with what I saw.

I've attached some pix showing what I saw. There is some frozen slush clinging to parts of it that was washed off (and allowed to dry) before the Krown was applied.

Tim

 

[Fubie]

I've never heard of Krown but looking at it I might consider it. How does it compare to other undercoating/protectant processes?

 

[lamont]

Known is one of the recommended coatings in the Rust Belt and other areas with road salt use. However I suggest you plug and seal the holes that you think should be plugged. Imagine fording water, and water, sand and little fish (possibly making love) inside the chassis.

 

[morning moon]

Aren't the bottom holes for drainage of the water? If they are plugged, water stays in chassis.

 

[lamont]

Aren't the bottom holes for drainage of the water? If they are plugged, water stays in chassis.

Primarily you want to keep water out. There may well be some strategically placed drainage holes. However, people have posted pictures of the chassis with random holes unplugged, and those holes were in my opinion too large to be drainage holes. They looked like holes that are used to spray cosmoline or similar into the hollow parts. And those holes should be plugged after being used. There are pictures in a thread on one of these here forums.

 

[Oldav8tor]

There aren't that many holes in the underside but of the ones that are there, some are large, some small. I would think the larger ones at a minimum should be plugged, after spraying an anti-corrosion agent inside.

Krown is a process developed in Canada and is different from your typical undercoating. It's more of a penetrating oil / water displacement compound and was originally developed for the aerospace industry. As Lamont says, it gets high marks up here where road salt is a concern. I don't believe it is available in most areas of the US but here is a link to N. American dealers https://www.krown.com/locations/all/ - Americans near the Canadian border sometimes cross into Canada to have it done. Fubie, there is a dealer in St. Louis if that is close to you.

In my experience, rust either forms where the paint has been scratched or chipped or eats out from inside a closed panel. Tailgates are particularly vulnerable. The Krown process should prevent rust from gaining a foothold on the inside where you can't see it.

 

[lamont]

Right, Krown is not available across much of the country outside the Rust Belt. At least there are no places that will apply it that i know of. There's a similar product you can buy anywhere and apply yourself. Amsoil Heavy Duty Metal Protector spray that leaves a wax-like film like thin cosmoline. I have used on the inside of body panels and doors, and under fender liners with good result. Fluid Film is similar to Krown and can be bought in spray cans.

 

[Fubie]

Fubie, there is a dealer in St. Louis if that is close to you.

Thank you for the info. I will be visiting the St. Louis dealer and investigate further. Thanks again!

 

[Oldav8tor]

Fubie,
Researching things like rustproofing is how I filled the time waiting for my Trailhawk to be delivered..... The thing is, the more info you have the more intelligent your decisions (RE: your Renegade) will be. I can tell you this much, it's worth the wait!

Tim

 

[lamont]

Fubie,
Researching things like rustproofing is how I filled the time waiting for my Trailhawk to be delivered..... The thing is, the more info you have the more intelligent your decisions (RE: your Renegade) will be. I can tell you this much, it's worth the wait!

Tim

Nobody has accused you about suffering from "analysis paralysis" [sic]? :x

I vehemently agree with you.

 

[Oldav8tor]

I took my Renegade in for it's annual re-treatment with Krown. While up on the rack the shop owner and I gave the underside a good looking over so I thought I would report back.

After a snowy, salty Michigan winter and driving all summer on brined back roads, I'll be darned if I could spot any new rust on the underside. It all looked very good to me and the shop owner agreed. I can't give all the credit to Krown but I did like what I saw. The visible exterior of the body still looks like new and I have only praise (no complaints) after 20,000 miles of driving.

Another product they have that might interest you is a spray that penetrates nooks and crannies and dissolves salt. You let it soak in for a few minutes then power wash it off. The shop owner recently did a demo for the Detroit DPW who is thinking of using on their salt trucks. For $20 I'll probably take my Renegade back in the spring and have the underside cleaned as a precaution. Can't hurt!

 

[mykeym]

OP the first picture that you pointed out where there is no plug in isn't part of the "frame" it is a support welded onto the "frame", also there are many drain holes in it so water buildup is negligible. However on the rear that is actually in the "frame" rail and should be protected. From the pictures you took I don't see any "missing" plugs, just holes that don't need them.


As far as the under coating I agree that it should be on all of it, however the stuff is heavy and mainly used for noise suppression anymore. My BMW M3 e46 doesn't have any on its underside so I think it is just a growing trend to only apply if deemed necessary by the manufacture.


PS Yes I know this is a unibody construction and doesn't have a true frame per say, however to help make my point easier for visualization I called the rails "frames"