Hard start after a parade in a 1952 Cadillac

[jdemerson]

I am sharing this experience here simply because it may be helpful information to someone with a 1950s model.

My car is stock 1952 with the 4-barrel Carter carburetor and mechanical fuel pump. It is in good operating condition and yesterday morning it started on the first try. I use only ethanol-free 91 octane gasoline and a little lead substitute added.

I drove it for 1 1/2 hours and was then parked for over an hour prepping the car and waiting for an early Independence Day parade to begin. The weather cleared and it was fairly hot (around 80 I think) by the time the lineup began. The parade was a fine one, very well attended and lasting 1 1/2 hours. [Aside: The spectators loved seeing the old Cadillac and I heard countless appreciative comments and saw many thumbs up.] So the car was moving at idle for a very long time, with an occasional blip of the throttle to boost the generator a bit (perhaps pointless...). After the parade ended I drove a mile and stopped in order to put a banner in the trunk and get out a light lunch. When I went to restart it, it turned over fine but would not start. I made several tries, and then gave up, not wanting to run down a battery that may already have been low because of the prolonged idling.

I had my lunch, waited 20 minutes with the hood up in the black car. Finally I went to restart it and it started easily and quickly. I drove off and an hour and 15 minutes later I arrived home with no problems.

My analysis: The engine was unusually hot because of 1 1/2 hour of running under load at idle. Then the car was turned off and the excess heat vaporized some fuel and blocked the gas supply to the carburetor. As soon as the gasoline returned to its normal liquid state, all was well. By the way, the temperature gauge was up at halfway mark during the parade but returned to about 1/3 when out on the highway. Of course I could have used a cold wet towel to make things cool down faster. And I know the clothes pin trick...

Further comments, different analysis, and free advice all welcomed!

John Emerson
1952 Cadillac Sedan 6219X

[Jon S]

I concur with your analysis. It could also be that the Ethanol-free gasoline is not so Ethanol-free. Just a thought. It sounds like vapor lock to me.

[35-709]

I concur also and just because the gas is ethanol-free it doesn't mean you can't get vapor lock --- just less likely.

[Jay Friedman]

I totally agree with Jon S and 35-709. 

IMHO, the "workout" you gave your '52 in the parade was a classic vapor lock inducing situation; that is, idling along for a prolonged period in warm weather.

One day last summer my '49 (in which I only use ethanol-free gasoline) and I were stuck in traffic for 30 minutes or so and the temp gauge slowly crept up to the 1/2 mark.  It didn't stall, but when I was finally free of the traffic and accelerated onto an interstate it skipped a few beats, meaning there was some air in the fuel. 

I have a 5-bladed fan meant for '49 limos and hearses that I keep meaning to install, which should move more air in such situations.  Just haven't gotten off my duff, because unlike the original 4-bladed fan which will slip between the fan hub and the radiator, the 5-bladed version will not so I'd have to pull the radiator to install it.

 

[TJ Hopland]

My way around that problem till I went EFI was an electric fan hooked to a wind up timer.   It apparently doesn't take much air flow under the hood to significantly reduce temps.   On mine if I would just pop the hood far enough that there were gaps on the sides that was enough.  After the fan I would just wind it up to between 5 and 10 minutes when I would park it hot.   Worked 98% of the time and during that time I was running ethanol blended fuel. 

[jdemerson]

For the record, I have not had any other instance of vapor lock since I switched to ethanol-free 91-octane fuel (the only ethanol-free gas available here) a few years back. I suspect that 1 1/2 hours in a parade on a warm sunny day is a killer!

Jay Friedman is very experienced in this area and his advice has been valuable. I share his preference to avoid changing to an electric fuel pump or adding a fan. On the other hand, if vapor lock appeared more regularly or under different circumstances, I'd do what is needed to have the car reliable and usable. For now I'll assume the situation was quite unique, and wait to see if vapor lock becomes an issue in more "normal" circumstances. Thanks for the comments and advice!

John Emerson
1952 Cadillac 6219X

[Jon S]

For the record, I have not had any other instance of vapor lock since I switched to ethanol-free 91-octane fuel (the only ethanol-free gas available here) a few years back. I suspect that 1 1/2 hours in a parade on a warm sunny day is a killer!

Jay Friedman is very experienced in this area and his advice has been valuable. I share his preference to avoid changing to an electric fuel pump or adding a fan. On the other hand, if vapor lock appeared more regularly or under different circumstances, I'd do what is needed to have the car reliable and usable. For now I'll assume the situation was quite unique, and wait to see if vapor lock becomes an issue in more "normal" circumstances. Thanks for the comments and advice!

John Emerson
1952 Cadillac 6219X

Totally agree!

[D.Yaros]

Turning off the engine led to a "heat soak" situation causing the vapor lock.  You correctly diagnosed the cause.