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Gas Tank Rust


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First of all I have been out for a while and just getting back to my z car. Quick summary I had some electrical issues that were causing the car to run at 18V. This has been fixed primarily with a newer internally regulated alternator and a little rewiring. Thanks to all.

Next issue appeared to be gas delivery. The car, after some checks, appears to be running lean. Previously I have replaced the fuel pump and fuel filter (not really related at least when replaced to the lean comment). I noticed when I removed the old filter that there was a lot of small brown particles on one side of the filter, clean on other. Both the pump and filter have less than 1000 miles on them. After breaking down for about the 20th time the car has sat for 3 months or so. I was moving from one house to another and car appeared to be starving for gas and eventually broke down (some white and black smoke from exhaust, mostly white). About 2 hours later the car did restart and with same symptoms limped another 2 miles. Then all of a sudden the smoke stopped and car ran fine. I was only about 1 mile from house at this point but never the less. Bottom line is I am almost convinced that I have some rust in the tank causing the issue. I have suspected this for sometime but just not willing to take the leap and drop the tank. I removed the somewhat new filter and again some small brown particles.

Comments? Suggestions? Sorry for the long winded post. Details on dropping and cleaning tank if I am at that point?

Thanks in advance.

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That access hole may just be on the later models because I don't recall seeing one on my 72'. Based off of what you have described, you do have rust in your tank. Removing the tank is not a difficult job, just be sure you have all the fragile hoses undone so nothing it torn out. A diagram of the tank will also help out greatly if you are not familiar with taking it out. Your best bet to cleaning the tank is having it boiling and sealed at a local radiator shop.


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White smoke if often coolant in the combustion chamber. This will drop the level of coolant in the radiator. A failed head or head gasket are the usual causes.

The only other white smoke source is water vapour condensing from the combustion process and additional water vapour condensing that was picked up in the exhaust pipes from overnight condensation on the cold metal exhaust walls. These visible white vapours on start will gradually convert to invisible steam when the engine and exhaust system heats up.

Here is a typical head gasket failure allowing coolant to enter the combustion chamber:


Here is another from a cracked head:


Here is a photo on a very cold day and you can see the white smoke from water condensing. This water is a byproduct of burning gas and is normally invisible:





Edited by Blue
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Got it on the smoke. All the photos are great. Since the car shows no sign of smoke when running good, at least on the outside, I am going to assume the best for now. I will begin the process of dropping my tank. Should I plan on disposing the 10 plus gallons of gas in the tank or is there a good way to filter for use maybe on yard equipment. I thought I would syphon some of the gas and drain out the rest. I would like to save the syphoned portion if I could filter while syphoning. I do not see a circle opening near the spare tire area (1976 2+2).

As far as repair goes my local shop wanted about $500 to repair. Seems a little high. Any other suggestions or is this the consensus instead of coating the inside of the tank myself?


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$500 is pretty high just to boil out the tank and seal it. At least around here. Maybe shop around some more, and see if you can find a better deal. If not, doing it yourself is an option. Several people here (including myself) have redone there own tank for a fraction of the cost. POR-15 sells a tank restoration kit that will work. Just make sure you follow the instructions as closely as you can or it will not work (ask me how I know). Before anything, get the tank down and see how bad the rust is. It may be too far gone and a new tank will be needed.


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Based on past experience should I expect to be replacing the fuel pump and fuel filter again? Where does the rust normally cause the problem? Just a reminder the car will run fine for a day or two and then break down. Wait a hour or so and run again sometimes good and sometimes bad.

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