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Cars with aftermarket undercoating.

Richard Davis

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I'm looking at pictures of a car from MA. The car is a '68 and has been sitting in (inside) storage since the 80's. Looking underneath the car looks to have several coats of undercoating. I remember companies like Zbart doing that sort of thing. In some areas the coating looks thin yet the metal looks really good. Other places the coating is really caked on. This is not POR15 or anything modern. This is old school.

Should I worry about the caked on areas? Was this old school undercoating effective? How hard is it to remove? The seller says the car was not driven regularly in the snow, and the underneath pictures seem to confirm this. I can attach pictures tomorrow if that will help.
 
In some areas the coating looks thin yet the metal looks really good. Other places the coating is really caked on.

I'm not a fan of undercoating and this is exactly the type of undercoating that scares me the most.
I mean why would you apply it like that if not to hide something?
 
sometimes moisture gets trapped under it and makes matters worse....... I never seen this with factory undercoat

most northeast cars were already rusty in the 80s, beware
 
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Most non-factory undercoating drilled holes and used plugs. Factory undercoating comes off with heat and an assortment of scrapers, knives, and brushes.
 
My Dad rust proofed customers cars. It was a amber clear waxy coating, it was applied inside as much as possible, doors, fenders inside rocker panels etc. One thing they did was drill 1/2" holes to gain additional access, which as kid concerned me, but they would plastic plug any drilled holes when finished. I was impressed with the results. Today I would assume the coating would outlast the car, as long as it didn't receive direct road/wheel spray. The competitors at the time black tar like "undercoating" just seemed like a good waterproof membrane to collect/trap water to actually promote rust IMO.
 
Most non-factory undercoating drilled holes and used plugs. Factory undercoating comes off with heat and an assortment of scrapers, knives, and brushes.
I have read old undercoating sometimes contained asbestos, which is today a third rail in these discussions.
 
A little off topic but ... just did this last week !! If the car is gonna be driven, you don't really want base/clear on there !!

91i.jpg


91l.jpg
 
My Newport had factory undercoating and it does dry out and cake off after so many years. Not all of it but a good chunk of it. See if it is a new application and if they are trying to hide something. In my case, I think the undercoating helped minimize rust as it was a northeastern car.
 
Here are some pictures of the underneath. This is a convertible so I'm concerned about the torque box and inner rocker panel in the 2nd picture. I'm contemplating an offer for the car and would like to get an opinion (best/worse case) on the cost of metal repair.

RearTank.jpeg


Area of concern:

ProblemArea.jpeg


You can see the caked on areas in both pictures but the trunk extensions and wheel wells look good.
 
a convertible from New England is a bit risky without putting a set of eyes on it in person
 
Stick your finger in the various holes and feel around for severe pitting and potentially thin spots inside the frame rails.
 
I absolutely plan on putting eyes on the car before I part with any money. I would assume that most problems start in the wheel wells. Here is the rear drivers side.

WheelWell.jpeg


The mileage on the odometer is really low. I thought it might be 100k+ miles but I think the shocks might be factory.
 
My Dad rust proofed customers cars. It was a amber clear waxy coating, it was applied inside as much as possible, doors, fenders inside rocker panels etc. One thing they did was drill 1/2" holes to gain additional access, which as kid concerned me, but they would plastic plug any drilled holes when finished. I was impressed with the results. Today I would assume the coating would outlast the car, as long as it didn't receive direct road/wheel spray. The competitors at the time black tar like "undercoating" just seemed like a good waterproof membrane to collect/trap water to actually promote rust IMO.
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I bought a sport car with this stuff shot into when new. what a mess. If oil gets to it it turns to goo. Also when it get hot it turns to goo. It had these yellow plugs in it where it was pumped in.
 
View attachment 1653013 I bought a sport car with this stuff shot into when new. what a mess. If oil gets to it it turns to goo. Also when it get hot it turns to goo. It had these yellow plugs in it where it was pumped in.
Just to be clear, My Father's rust proof system he provided was definitely not "Ziebert", how similar it was I do not know. Ziebert was a topic of discussion, and not sure if its avoidance, was cost based or another reason. We are in South Florida, not aware of heat being any issue ever. As far as oil causing any goo like outcomes, but being most undercoat systems or rust prevention systems were petroleum based, that outcome would not surprise nor bother me.
 
Bring an awl and start hammering away at the various sections, if there are holes you'll find them.

Looks like a solid car, in Northeast terms.
My wagon is the same, caked on factory undercoating, looks like tar in some spots, dried out in others.
I scrape off the dry areas and anything that is flaking, keeps water/debris from getting and staying behind it.

Underneath, I find the factory blue paint as good as new.
Some sections, where the water got behind it, or it dried up/fell off, there is rust, but certainly a small amount of the undercarriage.

Frame rails can fill with debris, poke around in them.
The rockers can hide a huge amount of debris, not sure why the body plugs were put in the ends of the rockers, those bottom 'drains' at the pinch weld are not big enough for 2 pine needles to get through.
I pull those rocker plugs and hose them out, leave them out.
 
Whenever I had a new vehicle undercoated I always bought a couple of spray bombs so I could get into all the hard to get to places.
 
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