I recently sealed my gas tank. It had been sitting for over 10 years and was badly rusted. Fuel pump roasted as well, but that's a different story. I used an Eastwood product that included multiple steps. There were 2 washes with different chemicles and a latex sealer. It was not difficult. Some tricks:
- The tank must be out of the car to do this. Only 4 bolts hold it in. Disconnect the overflow vents first. Remove the cover in the trunk where the fuel filler comes in to see where these connect. Take some time with a flashlight and a mirror to familiarize yourself with what's in the tank. There are small hoses and a baffle you need to be careful not to mess up. Use the fuel level sender hole as a viewing port.
- Buy a new plug for the bottom of the tank. Use the old one in the sealing process as it will get coated with the goo and be useless afterwards. I broke the screen part off.
- Get a heavy lenght of chain. Insert it in the hole at the top of the tank where the fuel level sender goes (keep this out of the tank during the process as the goo will mess it up. CAREFULLY roll the chain around in the tank to loosen the rust. Retrieve the chain and dump the loose rust out.
- Buy youself some very good acid gloves, a resporator and good eye protection. This is nasty stuff you're dealing with. Follow the directions carefully. You'll need some gallon containers like the metal ones paint thinner comes in to dispose of the used chemicals. Plastic would work too, but I think metal would be better. I have about 6 gallons of waste chemicals in my garage I have yet to figure out what to do with. You'll also need a large funnel.
- You'll be using lots of water and best to do this somewhere you don't mind dirty water getting spilled. Not something to be done in your garage or nice driveway.
- I did this project by myself, but a second set of hands to help with sloshing the stuff around in the tank would be helpful.
- You need to make sure the opening where the fuel is siphoned out does not get clogged. I used an air hose to spray it clear often. Again, take some time and really inspect how these tanks work. The pickup is down by the plug and is really clever. When you've identified the sensitive areas, you can be careful how you do the process. These tanks aren't just big barrels with a hose coming out. Those Germans have to make everything complicated. But at $800-900 for a new one, it's worth trying to restore.
- I also installed an inline fuel filter between the tank and fuel pump. The fuel pump is another very expensive part. I went to Pep Boys and got the largest canister with a paper filter I could find. Matched the hose size and just spliced it in. Seems to work well.
Hope this helps.
Bringing one of these cars back to life after a long sleep is like pulling the string on the sweater. Be prepared for problems. Don't go for any long drives for a while and always bring tool box and AAA card! Once you get the bugs out, the car should be pretty much trouble free. Mine isn't quite to that stage yet. I also have the benefit of a retired MB mechanic up the street. If you can find an old timer mechanic, buy him drinks, feed him cookies, do whatever to make him your friend. These cars are loaded with state of the art technology, from the 50s and 60s. Modern mechanics will scratch their heads when they can't find the computer port. Also, most of the parts were made to be serviced, not just replaced. This takes time and experience. Heck of a lot cheaper than a $900 fuel tank or $800 fuel pump!
Good luck.
Shawn Rock
Philly, PA USA
1968 280 SL 4 speed
