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Dynaflo2

'51 Roadmaster: Died, won't start. Waddaya think?

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OK, the car is safely tucked back into its spot in the garage, even though it had to suffer the embarassment of rolling off the back of a tow truck to get there. Here is what happened: I drove the car on three trips today. Each time, it started and ran like a champ. It got warm here; about 88 degrees. On the final trip of the day (about 7:00 pm), I went to a restaurant about 4 1/2 miles away. Again, absolutely no sign of a problem. After about 40 minutes I got back in the car and she started perfectly. I backed out of my spot, went about 30 feet and the engine sputtered and died. I noticed when I had first started the car that the aftermarket thermomoter was reading 220 or so. Normal running temp is usually around 180, even with the new thermostat, but the engine temp reading usually goes up when the car sits after running. My first thought was vapor lock. I couldn't get the car to fire. The battery is not good at holding a charge, so I got a jump and it still didn't start. I poured some gas in the carb and it still didn't start. It tried to catch once or twice only for a brief second, but with no luck. Moving the linkage, I wasn't getting any gas in the carb. That would seem to fit with vapor lock. What doesn't fit is the fact that the engine wouldn't catch, even with a splash right in the carb. So now I'm thinking ignition. Has anyone ever had a coil go out with no warning? If not the coil, what else? Right now the battery is toast again, but will be on a charger after I post this. I will try cranking the engine to see if I can get a spark off the coil wire (wearing gloves of course! I have been zapped by a coil wire before!) What else should I be looking at?

Another thought: I've never had this happen before, but could the carb itself have been so hot that it would vaporize the gasoline before I could jump behind the wheel and hit the starter?

Many thanks in advance for your help.

I must be off...

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Hi John,

Sorry I haven't gotten to you before. Glad the rearview mirror is working out.

Concerning your problem: My '51 Roadmaster was in a parade on Saturday and the parade was very slow. As a result, by the end of the parade, she was overheating and when I shut her down to cool off, she did not want to start for about a 1/2 hour. I think you are correct about the vapor lock. On the way home, the battery was charging quite a bit. My guess is that she will start right up after your battery is charged.

If that is the case, the bigger question is why she overheated so easily. Keep us informed. No more parades for me.

Rod

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Guest

we have a free 1950 buick group linked below.

I´m sure it´s a fuel pump or needle valve issue. vapor lock is an over rated problem.

before, the fuel pump, cut in a clear plastic fuel filter which will hang down by the starter.

now you can see what your fuel is doing, my guess is it´s all rust and dirt.

electrical problems are not effected be heat, and start showing signs before they go.

onece you see clean fuel moving, then you can goto the next issue.

where as I have the smaller engine, i still got my raditior recored because of the heat. a garden hose flush will not do it. you need at leased a $100 professional flush.

I have had my re-cored raditior flushed, again, after a period of years.

drove the car 1,000 miles to flint.

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I would tend to concur with the vapor lock diagnosis. What you experienced was heat soak, so even though the car runs at 180, that's with air moving over it and through the radiator. When you shut it down, that airflow stops, even though the moving parts of the engine are still at operating temperature. Hence, heat soak and the high temperatures. Once you get moving again, the temperature will quickly drop back to normal.

Anyway, it's quite likely that heat soak made the carb so warm as to make fuel difficult to atomize (or already vaporized). On these cars, the proximity of the carburetor to the exhaust manifolds exacerbates the situation of heat soak. Add in a fuel line that runs right above the exhaust manifold and a marginal mechanical fuel pump, and there's the problem. I might also go with Tommy's suggestion to make sure your lines are clean and your carburetor is in top condition. Vapor lock isn't common, but it does happen. As he said, start checking things out until you find the problem. But I'm going to stick with the heat soak theory.

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WE HAVE A WINNER! After a little time on the battery charger and a couple of splashes in the carb, she fired right up and wondered what all the fuss was about. Looks like vapor lock was the problem. It's happened a couple times before, but was only a minor annoyance then. I've never had the car just quit on me like that before. And I've never had an occasion where the carb was so hot that the fuel couldn't do its job. So Rodney and Matt each win a fish.

Tommy, thanks for your points. I should have mentioned that the carb was just rebuilt two years ago and I had a complete engine flush about 9 years ago. That sounds like a long time, but it only translates into about 6,000 miles.

As for preventing the same thing from happening again, I'm thinking I should:

1) Insulate the fuel lines.

2 Finally install that electric fuel pump I've been mulling over for years.

Thanks for all the help guys!

I must be off...

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Electric fuel pumps are for the weak!

Have not had one on my car is 19 years......

´27 still runs a vaccum tank with no issues, or vapor lock, and that car hold a quart of gas under the hood.

gasoline, electric, and a wood body..... a rolling barn fire.

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Have you checked to make sure that your heat riser valve in the manifold is functioning properly? If it is stuck in the closed position, you will experience exactly the problem you have.

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Joe,

Thanks for that excellent point! The heat riser valve hasn't worked in the dozen or so years that I've owned the car. I've hit it with penetrating oil, PB Blaster, and a ball peen hammer (firm taps only!). I had completely forgotten the thing was frozen. If I remember correctly though, it is frozen in the "already warm" position, so it should be sheilding the carb. In any event, I will soon be replacing the gasket between the exhaust manifold and the heat riser. While I have it apart, I'll have another go at the heat riser valve.

By the way, Joe, you and I met at the Flint National. I'm sure you don't remember me. You were being mobbed like the rock star you are.

As for being a weakling with an electric fuel pump or a he-man waiting an hour for a tow truck, it may be time to start calling me Nancy. I have resisted the electric fuel pump idea for years, even though the car is very tough to start after sitting. It's hard on the battery, generator, and starter to get past the fuel starvation that takes place after only a few days. If I had given over to my inner weakness already, it would have saved me the time in the parking lot and the tow truck ride. I haven't pulled the trigger on the fuel pump yet, but the safety is off.

Thanks again for your input guys!

I must be off...

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if it will not start after sitting, you have a weak fuel pump or a gasket leak.

my 1950 starts on the fourth crank after sitting two months.

pushing fuel into a hot place is never a good idea!

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Dyna:

Most old cars have problems with the evaporating tendencies of our modern fuel and are hard to start when hot. But this problem is really exacerbated when you have a weak battery and poor wiring connections to your distributor or from the battery. The voltage drops severely when cranking an old, hot engine with a weak battery. There is barely enough spark to ignite the poor fuel mixture that you get when the carb is hot after parking your car.

I have really improved the hot starting capabilities of my old cars by getting decent batteries in them with new substantial cables and connectors. Make sure the starter is in good shape too, poor grounds and brushes reduce the starter drive torque and ends up drawing extra current that your ignition systems needs.

With strong ignition and cranking speed, you can usually get a hot engine started, though mine run very poorly and want to stall for several miles -- until fuel coming into the carburetor from the tank finally cools off the carb enough to stop the boiling in the carburetor. Avoiding gasohol (10%ethanol) also helps, the gasohol has a lower boiling point than gasoline.

Bill.

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I think "Buicksplus" has just given some excellent advice. I agree with everything he said. Nearly every straight 8 I've ever had has had bad connections, dirty connections, or bad grounds at the starter, and a weak battery makes everything worse.

Also, do you have the thick 6-volt battery cables on your battery? They should be about a half-inch thick. 12-volt cables are much thinner, and will not do the job when the engine is warm. I learned that the hard way.

Pete Phillips, BCA #7338

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The larger gauge 6-volt rated battery cables will carry more current than the smaller gauge 12-volt rated battery cables. The actual current is carried around the perimeter of the cable strands rather than in the middle, which makes the cable's assembled diameter important.

It would be a good idea to clean and check ALL electrical connections in the charging/starting system. A weak battery terminal connection can cut down the ultimate alternator output by 10%+ in a 12 volt system, so you can see where that would leave things in a similar situation on a 6 volt system and less generator output. From experience, unless you've cleaned the battery terminals recently, you should consider doing that too--that's where the electrical current path starts and stops.

Enjoy!

NTX5467

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