our51super Posted January 6, 2004 Share Posted January 6, 2004 Hi All,Happy New Year!I am trying to help a club member out and I wanted to get your feedback on this problem.According to the car owner, the gas tank leaks only when full. I am not very familiar with the '58 Buicks and I have not yet looked under the car. I would imagine that there must be some kind of an overflow valve perhaps which might be attached to a hose that has rotted.Any help/insight would be greatly appreciated.Thank you in advance. Link to comment Share on other sites More sharing options...
GSTURBO Posted January 7, 2004 Share Posted January 7, 2004 My 67 GS has leaked when full for years so I dont fill to the top except when I leave on a trip. Link to comment Share on other sites More sharing options...
brad54 Posted January 7, 2004 Share Posted January 7, 2004 My '54 Special had the same problem. On it, the gas gauge sending unit/fuel pick-up exits on the top of the tank, and the gasket that seals it was shot.Now, on my '57 Chevy, there is a gas tank vent tube that runs up to the fuel filler door, and there is a nipple on the tank for this, with a small rubber hose running up from it. In '56, Chevy didn't employ this. Both cars are GM, and it's possible Buick was doing something similar with their tanks, and Chevy made the change in '57. Check those two things, and one or the other should cover it.Worst case is that there are pin holes in the top of the tank from moisture getting up there between the floor and tank. I've seen that, too.Hope this helps,-Brad Link to comment Share on other sites More sharing options...
The Old Guy Posted January 7, 2004 Share Posted January 7, 2004 I am not sure about the 58, but the 57 had a rubber line that attached to the frame as a vent tube. When the rubber went bad, the fuel instead of haveing to travel up the hos, came out the opening. This hose made a loop that kept the fuel from sloshing out the top. Link to comment Share on other sites More sharing options...
dobieroo Posted January 7, 2004 Share Posted January 7, 2004 This doesn't address the issue on the 58 directly, but for reference I wanted to chime in and get share my experaince here. I just dropped the tank on my 56 Roadmaster and there is no vent tube or hole. Just the pick-up unit screwed into the top and the tank has a tight fit against two rails attached to the underside of the trunk pan. Link to comment Share on other sites More sharing options...
Smartin Posted January 7, 2004 Share Posted January 7, 2004 Sounds like Hank needs to drop his tank....Or have Bob do it An excellent project for tonight ....8* temp Link to comment Share on other sites More sharing options...
JohnD1956 Posted January 8, 2004 Share Posted January 8, 2004 My 56 tank did the same thing. 3/4 tank okay, full tank leaking slightly but enough that I couldn't park it in the garage. So I had the tank reconditioned at a local gas tank renu dealer. Beautiful job! Put it back in and filled it up, and it leaked again. Boy, was I ticked off. Dropped it a second time and they sloshed the gas around to search for the leak. They found that the two rivits that hold the sending unit together leaked. They debated soddering or expoy. They were concerned that heat from the sodder process would damage the reostat(sp?). So they epoxied and let it dry for a week, and all's well. I can fill it right to the rim of the cap and no problems. Link to comment Share on other sites More sharing options...
brad54 Posted January 8, 2004 Share Posted January 8, 2004 You know, that's an awesome tip! As a matter of fact, just to avoid potential problems in the future, I'm goint to make it a habit of putting epoxy on the rivets of sending units before I install them from now on. It's probably a rare thing, but I dropped the tank in my '54 several times for various problems, and before the trans fiasco I had with it put it in dry dock, it developed another leak at the top of the tank, even after putting in a new gasket. (the gasket was rubber, so I attributed it to that, or to the screws that hold it in the tank leaking)-Brad Link to comment Share on other sites More sharing options...
our51super Posted January 8, 2004 Author Share Posted January 8, 2004 I want to thank you all for your inputs. Since the gas gage doesn't work on my friend's car either I'll have to drop the tank and replace the sending unit as well. I will take all of your inputs with me and let you know what the problem is. The 8 degrees should not be a factor as this gentleman has a heated garage. (That's on next year's Christmas list for me. )Cheers! Link to comment Share on other sites More sharing options...
JohnD1956 Posted January 9, 2004 Share Posted January 9, 2004 I also endorse the gas tank renu process. That stuff stayed on with no ill effect when it leaked. Plus, I had even had dents in my tank ( an embarassing story of lack of common sense) which they were able to press out so you cannot tell the tank was ever damaged. I had a choice of shiney silver, but my car is still undercoated from it's early days, so I went with the black undercoated look. Probably the best money I spent on the old girl. Link to comment Share on other sites More sharing options...
Charles2 Posted January 9, 2004 Share Posted January 9, 2004 You will probably want to check to be sure you don't have pinhole leaks in the upper surface of the tank. I have the tank out of my 40 right now and have found about 20 pinholes from road salt on the top and upper sides of the tank. I am still cleaning the tank so I don't think I've found all of them. I plan to solder as many holes as I can find and then slosh the inside of the tank with POR-15 sealer. I am experimenting with cleaning the rust from the inside of the tank electrolyticaly. It seems to be working real well; it is slow but exceedingly thorough. It electrochemically removes all of the rust. Good luck! Link to comment Share on other sites More sharing options...
baking Posted January 9, 2004 Share Posted January 9, 2004 On my 70 Skylark I could smell a gas leak when the tank was full. Turned out the seal on the gas cap was bad. I bought a new cap and haven't had any problems since. Cheap and easy..... Link to comment Share on other sites More sharing options...
Patrick W. Brooks Posted January 11, 2004 Share Posted January 11, 2004 Good Morning: Recently had a leak on a gas tank only when it was full or near full. Finally found the leak and it was a small crack in the solder where the filler neck is soldered to the tank. The crack was very tiny and leaked slowly and was very hard to see. Finally found it when the car was on a lift and had been driven so the wet lines were visible. Hope this helps. Patrick W. Brooks, BCA #3939 Link to comment Share on other sites More sharing options...
Smartin Posted January 12, 2004 Share Posted January 12, 2004 Crin,Dropped the tank yet? Link to comment Share on other sites More sharing options...
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