highcking

I think that’s what I used also. I put gas resistant sealer on the screws and tightened the assembly down VERY carefully. I plan to siphon down the tank and let my shop take a look.

Danchuk 1955-1957 Chevy Gas/Fuel Tank Sending Unit Gasket, Nitrile & Cork, Also 1953-1960 Corvette (Best) Item Number: 195D Your Price: $4.05 EA In Stock Qty:

Good question. Where did you buy the one you’re using?

That’s what’s on there now! I had leaks with the thin neoprene type so I switched to the cork style. This worked well for the past year, until the latest tank fill up. It may just need a SLIGHT turn on the screws. Thanks for letting me know it works for someone!

My question was posted on two forums. If that is against any rules, I apologize. I don’t know about the @ business. The answer is that gasoline is in fact leaking slowly at the tank sender. But the gas is evaporating on the cold metal, causing a watery condensate to drip that has no gasoline left in it. Odd phenomenon. I’ll have to go after the sender unit seal yet again, or just never fill the tank over half full.

Got the Buick on the ramps and determined that leak is definitely coming from the old problem spot, the new and carefully installed tank sending unit. So gasoline is getting out. But why does the leaking fluid look more like dirty water and have no odor? My guess pending further research is that the leaking gas in humid conditions is evaporating on the cold metal surface of the tank and causing it to sweat water on the outside. The dripping condensate is essentially water tinted either by the gasoline itself or by the sealant on the sender unit gasket. I was able to get a little flame from the condensate because the gas is not fully mixed with the water. When this happens inside the tank and is sucked into the pickup, your engine stumbles or stalls.

John - thanks for the reply. On the trunk — all that’s in there is the very dry car cover for the car. On the underseat heater, I would have gone for it 3 years ago when everything was apart and the interior stripped. It would be a nightmare now. My immediate unhappy task is to YET AGAIN take off the top if the dash to get at the speedo cable (long story) and a just-recently-broken heater fan switch. This car is like this: fix one thing, two more go wrong. Bill

Joe - when I restored this car a few years ago, it was missing the under seat heater assembly. I looked for one but came up empty and left it out as I had to keep going. No hoses under there. Next week I may let my shop put the car on the lift and search. Love that wagon! Bill

In the past I’ve had trouble with a gas leak at the tank gauge when the tank was full. This problem was taken care of over a year ago with a new gauge, seal, and installation procedure. Yesterday I topped off the tank, and later on noticed a fluid leak right below the gauge sender unit. If that fluid were gasoline, I’d have a problem but not a mystery. But I don’t think it is gas. Catching it in a drip pan, I find that the fluid is pale green, has very little odor, is a bit oily to the touch, evaporates slowly, and will combust slowly when touched by flame. All these factors lead me to believe the fluid is antifreeze. (The cooling system has a green mixture.) The gas gauge area is the low point of the tank flange which explains why it overflows the flange there. The mystery - how is antifreeze getting to the outside top of the gas tank? The radiator is full and I have not driven the car much in months. On the drive to the gas station and back I was making 55 mph which would have blown away anything already in the tank flange. There are no coolant hoses that far back. Ideas anyone?

In the past I’ve had trouble with a gas leak at the tank gauge when the tank was full. This problem was taken care of over a year ago with a new gauge, seal, and installation procedure. Yesterday I topped off the tank, and later on noticed a fluid leak right below the gauge sender unit. If that fluid were gasoline, I’d have a problem but not a mystery. But I don’t think it is gas. Catching it in a drip pan, I find that the fluid is pale green, has very little odor, is a bit oily to the touch, evaporates slowly, and will combust slowly when touched by flame. All these factors lead me to believe the fluid is antifreeze. (The cooling system has a green mixture.) The gas gauge area is the low point of the tank flange which explains why it overflows the flange there. The mystery - how is antifreeze getting to the outside top of the gas tank? The radiator is full and I have not driven the car much in months. On the drive to the gas station and back I was making 55 mph which would have blown away anything already in the tank flange. There are no coolant hoses that far back. Ideas anyone?

On my 58 Roadmaster, the rotary blower switch has always worked fine. I’ve turned it maybe 5 time in 7 years. Today in cold weather I decided after warming up the car to check out the heater, which I worked on when the car was apart. Of course … the blower didn’t come on and the switch had a strange feel to it like something had worked loose. By wiggling back and forth a lot I got the blower to come on, so it’s working. But the switch is not and I plan to replace/repair with an eBay unit. My question. I see the Dagmar knob has what looks like a set screw, but tries with various Allen wrenches did not seem to free the knob from the shaft. Is that in fact a set screw …. Or something else? I have to pull the top of the dash anyway to replace the speedo cable, so I’ll go after this switch at the same time. Bill in Luray

Question on my 58 Roadmaster. If I shift it into reverse when it’s still idling a little fast, I get a loud clank from the front end area even if I’m holding the brakes tight. It sounds like a typical frayed/loose U joint. But what does that mean on a Flight Pitch Dynaflow car? I see there’s a U joint inside the torque ball at the back of the transmission. Is that the likely source of the noise? Or something else? Bill in Luray

Jon - thanks. I’m running with standard breaker points. I do need to look at fast idle. Buick specifies 1500 on the top step of the cam. That’s very fast, but I guess it shouldn’t stay there long, especially in hot weather.

Too hot today, 90 degrees, to play with the choke setting. I did try running the car with idle screws at one turn out, very lean. Would not idle. It will idle at one and a half turns but I already knew that. Because the bogging problem seems relatively insensitive to these various adjustments, I may need to pursue the carb base vacuum leak. Manifold vacuum is over 17 and steady and I hear no hissing, but tomorrow I’ll listen with an engine stethoscope. I assume a very small leak at the base gasket can disturb the air fuel mixture at low rpms. Spraying the base to find a leak is actually not simple due to things in the way and air coming from the fan.

The Buick manifold design sends hot exhaust gases through the body of the carb. Cadillac likewise. A Carter AFB is made of aluminum which is quickly eaten up by exhaust gases. Both Buick and Cadillac shop manuals call for a blockoff plate to prevent this. The plate itself gets hot and transmits that heat to the carb body, but not as fast as direct contact with exhaust gas.

Ben - yes on the carb heat manifold. It has been blocked off. Ken - good point about manifold vacuum. The Buick has an oil pump vacuum booster that is piped directly to the intake manifold, I forget exactly how at the moment. In my experience with three 58 Buicks, these don’t work worth a darn. With my current car I got caught in a sudden rain shower, and sure enough, the wipers would virtually stop when I accelerated. Back in the day, Trico sold an electric vacuum booster pump that actually held vacuum steady at 15 or more inches. Later today I’ll try the choke reset and lean out the idle screws as you suggest. It’s a hot day today in Virginia which will affect the choke setting slightly. I’ll also check the fast idle and check once again for a tiny base gasket vacuum leak. Bill

A few tries today in good weather. Accel pump is spurting on both nozzles as it should, I checked using a snooper scope. Choke manipulations: factory setting is index, I tried two rich and two lean, no discernible impact. Choke back to index, I tried idle mixture screws at 1-1/2, 2, and 2-/2. No effect. Let me be more specific on the phenomenon. Cold engine, start car, idles smooth, touch throttle gently, engine lags for a few seconds or dies. Jam throttle down, there is a momentary hesitation but engine does pick up pretty fast. I have one other option, try the other AFB rebuild I have on hand. Nuisance to swap, though. I never liked Rochesters on this car.(

Ken - very helpful! I’ll continue to pursue along those lines. The internet is packed with threads on the AFB flat spot, on many different cars.

Pushing the choke to rich settings didn’t help, nor did setting the idle screws a turn richer. Let me be a little more specific about what’s happening. Start cold engine, goes to fast idle. Weather is warm so this may be around 1,000 rpm. Vacuum is at about 18, good for 58 Buick. Run just until fast idle is off, then shift to drive and gently squeeze the throttle. Engine will either die or sag way down. If the latter, it recovers after a few seconds. This behavior continues until engine is warm and choke is open. Could this be a rich stumble rather than lean stumble? Tomorrow I plan to look at the accel pump action.

I had that thought too. I’ll try the choke adjust first, maybe one notch. If it doesn’t improve, I’ll reset the choke and try idle screws.

I’ve finally gotten the Carter AFB on my 58 Buick Roadmaster to function well … with one exception. When the engine is cold, even minimal throttle forward or reverse kills the engine. Five minutes’ warmup and the flat spot disappears. Car runs and accelerates fine after that. My feeling is that it’s a slight fuel mixture problem at idle. Accelerator pump issue would continue on a warm engine. Thoughts on this? Bill Lursy, Va

I have a baffle plate the looks just like the gasket. I have another that is just a plain square open in the middle.

I have that flange gasket. What does that baffle look like? And what is the correct order of installation?

Yes, it has that feature. I believe it’s a correct AFB for the car.

Carb is Carter 2840s.