Undercoating removal / reapplication

IDMT

Member
I recently acquired a 90 SW. The truck is leaking in several places but was hard to trace given years of detritus so the shop asked that I degrease and pressure wash the bottom in prep to trace leaks and rebuild the axles. The process of removing 28 years of gunk also took a good portion of the rubberized undercoating. I now have a motley underside of this rubberized coating. In full disclosure I probably could have gone easier with the degreasing/washing. I'm concerned I created a bigger issue by trying to clean up the truck. What's the best way to reapply some rust protection? Do I need to strip the whole thing now that I've removed certain portions? The neurotic in me says I've opened pandoras box and worried about the repercussions.
 

IDMT

Member
Low light conditions but this is best I could do before sunset here in mountain time. The last pic looks worse than it is because of flash but there’s galvy liners in there behind this cake of rubber coating.
 

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evilfij

Well-known member
Oh. You have nothing to worry about.

The undercoating in the first four pics are on the underside of the tub is aluminium. The fifth and ninth are the inner fenders which are galvanized. The others are the frame.

Hard to tell what was on there, but the frame looks like external black waxoyl. It could be something else though. Get a can roversnorth sells it, and touch it up. It will be fine and the frame is all that is going to rot. The rest, if you want it to look nice and black, you can do the same or use whatever you want from black epoxy paint to black waxoyl to whatever the local auto parts store has. I tend to avoid parts store rubberized undercoating, but for aluminium like the underside of the tub it won’t matter.

While you are down there, get a few cans of Eastwood internal chassis coating (or similar, waxoyl makes a product too) and spray the inside of the frame. The frames tend to rot inside out and this is the best way to keep them nice.
 

lcdck

Well-known member
I've had good luck removing this stuff with turtle wax bug and tar remover. It's still a chore but it breaks down the coating a bit.
 

IDMT

Member
Thanks all for putting my mind at ease. Do you think I need to fully remove one coat in order to recoat? Said another way does it require entirely stripping the old to put on the new? Concerned about sealing in moisture or other impurity that causes more harm while I try to do good! For what its worth I'm up in ID so relatively dry climate with no salt on roads etc.
 

MountainD

Technical Excellence Contributor
Oh. You have nothing to worry about.

The undercoating in the first four pics are on the underside of the tub is aluminium. The fifth and ninth are the inner fenders which are galvanized. The others are the frame.

Hard to tell what was on there, but the frame looks like external black waxoyl. It could be something else though. Get a can roversnorth sells it, and touch it up. It will be fine and the frame is all that is going to rot. The rest, if you want it to look nice and black, you can do the same or use whatever you want from black epoxy paint to black waxoyl to whatever the local auto parts store has. I tend to avoid parts store rubberized undercoating, but for aluminium like the underside of the tub it won’t matter.

While you are down there, get a few cans of Eastwood internal chassis coating (or similar, waxoyl makes a product too) and spray the inside of the frame. The frames tend to rot inside out and this is the best way to keep them nice.
There are supports the run across the frame rail, riveted to the tub. Those are all steel, in their infinite wisdom…. I’d protect them 100%. If you ever remove the tub, take them off and have them galvanized.
 

erover82

Well-known member
How much of a perfectionist are you? You can clean and re-spray underlining relatively easily to get a somewhat uniform appearance back. It'll protect the body metal from flying debris and dampen sound a bit. To do it right would be a lot of work and involve stripping all the underlining and reapplying, possibly disassembling the body to do so. You could also go the wax route but in your climate it's not critical.
 
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Siia109

Well-known member
I have a hard time thinking a mechanic couldn't trace out a leak. They may have to wipe down an area and wait for it to come back but 95% of the leaks on these are a little like betting what direction the sun will rise - its pretty intuitive. Chances are there is not any undercoating on the engine or gearbox that would hid the source of oil. Do they have experience with LR's?

I had a shop that didn't want to touch any British vehicle - even if it was a mechanical and not an electrical fix. This maybe applicable here after all leaking British cars are kinda like the sun coming up in the east so this gets it out of his shop.

Its a strange request unless the overspray is just horrendous - but even then he should be able to hone in on general areas of where its coming from in my shadetree mechanical opinion....
 
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