C1 gas tank undercoated?

[James F.]

I bought a used original AOL logo gas tank for my '61. It's in great clean shape inside & out. There is undercoating in the center where the 3 cut-out holes are in the body, and outside edges by the drain and opposite side . It appears to be spray-thru from under the body. Did GM ever spot undercoat the tank in those areas, maybe because they were exposed? There is really clean metal underneath the thick undercoating. Nothing else on the top or sides of the tank.

[Terry D.]

Re: C1 gas tank undercoated?

Since the cars were never undercoated from the factory my guess is someone else did the undercoating.

[James F.]

Re: C1 gas tank undercoated?

Hi Terry - That's the only conclusion, it's old & thick. I bet the dealer said "You don't want the fiberglass to go bad"! Take care Terry, how's things in Akron?

[Frank D.]

Re: C1 gas tank undercoated?

People forget how hard Ziebart and others pushed their rust-proofing undercoat products "back in the day".
A TON of people bought into that goo and I saw a lot of cars slathered in it back in the '60s/

[James F.]

Re: C1 gas tank undercoated?

Hi Frank - I was at a dealership in the 70's. Undercoating and other "dealer prep" was how they made money on new cars. Then we had to work around that "stuff". I can't believe they talked this owner into using it on fiberglass. Did you restore your '61?

[Frank D.]

Re: C1 gas tank undercoated?

Hi Frank - I was at a dealership in the 70's. Undercoating and other "dealer prep" was how they made money on new cars. Then we had to work around that "stuff". I can't believe they talked this owner into using it on fiberglass. Did you restore your '61?

It was sort of a "rolling restoration", a rock solid, good bones, 270hp car with a few paint and "correctness" issues which I dealt with over my 10 years of ownership. I did eventually add a Tremec 5 speed and a Stayfast top as I drove the snot out of the car...

[Gary B.]

[Mike E.]

Re: C1 gas tank undercoated?

The way you describe it, my bet is that it is not undercoating. It is old dry, hard gear oil from the rear end, mixed with dust and dirt. A leaking pinion seal (extremely! common) does that as it slings oil in a 360-degree pattern. The exhaust, if you had the car, would have similar coating, hardened by the heat of the exhaust.

I bought a used original AOL logo gas tank for my '61. It's in great clean shape inside & out. There is undercoating in the center where the 3 cut-out holes are in the body, and outside edges by the drain and opposite side . It appears to be spray-thru from under the body. Did GM ever spot undercoat the tank in those areas, maybe because they were exposed? There is really clean metal underneath the thick undercoating. Nothing else on the top or sides of the tank.

[Frank D.]

Re: C1 gas tank undercoated?

The way you describe it, my bet is that it is not undercoating. It is old dry, hard gear oil from the rear end, mixed with dust and dirt. A leaking pinion seal (extremely! common) does that as it slings oil in a 360-degree pattern. The exhaust, if you had the car, would have similar coating, hardened by the heat of the exhaust.

This would be my guess....I just detailed the bottom of my 63 and the worst of the mess was the congealed and hardened grease thrown off the half shaft and driveshaft U-joints. At first I thought it was black out but a good soak in lacquer thinner, attacking it with a plastic scraper and a scratchy pad and hours of work and the stuff gradually lifted off the fiberglass.
The vertical fiberglass just forward of the half shaft inboard U-joints was the WORST!