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Vacuum Follies

Started by Dave Burke, March 06, 2014, 09:46:00 AM

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Dave Burke

Hi Fellas,

If you haven't figured me out by now, lemme set Y'all straight: if it ain't broke, then don't fix it - but if you are determined, make sure you break it really good before you attempt the repair!

Now that's out of the way, I think I goofed things up and my '57 Sedan Deville won't run, and I think it's because I was trying to do something smart.  The car has, as far as I can tell, the original gas cap.  But sometimes I would walk behind her and could smell gas.  High-test being expensive as it is, I figured that a smart feller would do something about that so I took out my compass-cutter and some gasket material and cut a nice new thick gasket for the cap.  Sure, it was harder to put on, but there was no gas smell.  And then the fun began.

The car from time to time started acting like it was vapor-locking.  I added a clear fuel-filter and it looked like there was air being drawn into the fuel system because it bubbled fiercely, and it seemed like the carb wasn't getting much fuel.  Finally the car would die and would not start again.

Fast forward to the other day, after I spent money to have her towed home from downtown.  As a prep to the planned trip to Florida, I decided to blow the fuel line clear with compressed air.  I put the air gun to the hose, pressed the trigger and...  RESISTANCE.  Air came out of the line when I pulled the gun away.  I repeated the procedure and heard a "thud" - the new fresh dent in the fuel tank that I had noticed was now gone. 

Nature abhors a vacuum, which probably explains these headaches I have been getting.  The fuel pump, doing its darndest, created a partial vacuum in the sealed fuel tank and ultimately was unable to work against it.  Or so it seems.  Now I have a cruddy carb.

Oh well, the learning is part of the fun, right?

Best,

Dave Burke
CLC# 27968
1957 Sedan Deville
1963 Series 62 - Project LUX
1983 Maserati Quattroporte

"Who loves ya, Baby?" - Kojak

Scot Minesinger

so the gas tank is now back to being vented and all is good?
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Dave Burke

Yeah, I pulled the gasket off the fuel cap - I guess I need to find another.  As far as I can tell, the fuel tank vent vents into the neck of the filler tube.  I'll see if I can find a vented cap though.
1957 Sedan Deville
1963 Series 62 - Project LUX
1983 Maserati Quattroporte

"Who loves ya, Baby?" - Kojak

Jeff Rosansky CLC #28373

Sounds like you got it.  The tank will oil-can without a vent. 
The thing I wonder tho is that in 57 they weren't as concerned about emissions so I would have expected a direct vent somewhere.  I'd look in the shop manual to be sure.  It may be blocked by something.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Dave Burke

Hi Jeff,

Nope - there apparently isn't one.  So I'll find a vented cap or I'll make one of my own.

What are these "emissions" of which you speak?  The only ones in the 1950s that I am aware of are Coca-Cola burps and nuclear fallout!

Best,

Dave
1957 Sedan Deville
1963 Series 62 - Project LUX
1983 Maserati Quattroporte

"Who loves ya, Baby?" - Kojak

gary griffin



Many years ago I had a Ford truck on a job site and it's gas was being siphoned by neighbor kids, so a genius employee of mine put on a locking gas cap.  It worked O K for short jaunts but when I sent it to pick up a trailer a hundred miles away my guy was complaining about the truck stalling.  The tank was collapsed and thereafter it only held 9 gallons.  I threw away the gasket and the problem was solved!!
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1957 Cadillac 60-special (Needs a little TLC)
2013 Cadillac XTS daily driver