Jump to content

1950 DeSoto stalls in traffic jams


Wilf Sedanet

Recommended Posts

My 1950 DeSoto stalls when I'm in a traffic jam and will not start up until I wait 15 minutes for it to cool down. It starts with idling at a lower pace, then it will run erratically and slow down even further until it stalls competely.

On a hot day, while filling up at the gas station it also won't start up after standing still.

It seems the waiting time can be sped up when opening the hood. I tried starting it by flooding and by not using the pedal at all but that does not seem to make any difference. It just does nothing but crank but no firing up what soever (not even a single burble).

I was thinking that this could be a problem with the fuel line (boiling gasoline) because the line runs alongside the engine and manifolds. Is this a plausible cause?

The cooling system has been flushed and I have a three row radiator; the cooling system is okay and the water temp never exceeds the upper limit, even in a traffic jam on a hot day.

Here a picture of the fuel line:

59AC1D24-6C2B-4C2A-B5B3-D501AAB640E6-342-000000653F4B7584.jpg

Is this the usual place for the fuel line and do other people recognize the problem?

Link to comment
Share on other sites

I had a similar problem with our 48 Chrysler, I changed the condenser and solved the problem. Your fuel line looks to be about the stock location, it is hard to find an original line that hasn't been cut for a filter. I had to make a fuel line for one of our cars, it comes out of the carburetor pointing front and makes an immediate right turn to get away from the exhaust manifold. This car usually will fire up easily after a hot shutdownpost-39071-143142331458_thumb.jpg

post-39071-143142331456_thumb.jpg

Link to comment
Share on other sites

With respect to the fuel line location, it is a bit closer to the exhaust manifold than mine. Not sure how much difference that makes as the gas should be under pressure there and any the vapor from boiling fuel should rise into the carb and be vented anyway.

Dies while idling? On my car that occurs when the fuel pump overheats and I can get it restarted immediately by cooling the fuel pump down (a little drinking water poured on the pump does the trick). Installing an electric pump away from the engine heat would solve that too but that is non-stock. For what it is worth I did not have this problem until they started putting alcohol in the gas. My guess is that current blends of gas vaporize at a lower temperature than what was sold way back when my car was built. My car did not come with the fuel pump heat shield but I understand that retrofitting that from a later car was a factory authorized fix so maybe I'll do that some day.

Won't start after short running on a hot day? Most likely gas percolating in the carburetor and flooding the intake manifold. Make sure you have the phenolic block under the carb and maybe set the float a bit lower. My car has never exhibited this symptom so either I'm lucky or my engine compartment is not as hot around the carb as others.

Link to comment
Share on other sites

Thanks for the wise advices, I will look into the heat shield, ply33. Jazzer3, your custom fuel line looks good! What do you mean with the condenser? Do you mean the heat exchanger for the cockpit temperature? Because it does not seem to be a water cooling problem..?

I was also thinking it could be the carb itself indeed so I'll see what the float height is. I didn't find any carb kits for this carb so I think it still has all the original parts in it.

The fuel here in The Netherlands is not only expensive ($8,85 per gallon) but also diluted with all those ecofriendly dopes etc so that does not help too…

@ jazzer3: another thing I just noticed: You've got louvers in your wheel arch, maybe that helps for heat exchange too!

Edited by Wilf DeSoto (see edit history)
Link to comment
Share on other sites

Carry a bottle of water in the car with you when it stalls pour it on the fuel pump and gas line it should start right up. (VAPOR LOCK) Bill WEB38

Link to comment
Share on other sites

0_IMG_2530.JPG

If you look at this pic you can see the heat shield that goes between the fuel pump and the exhaust manifold.

This is necessary, especially today with the alcohol gas, to keep the gas from boiling and creating vapor lock

which seems to be your problem according to your description of what is happening.

Link to comment
Share on other sites

Thanks for the picture. Is this a plain piece of metal and how is it attached? My shop manual makes no notion of the heat shield.

Yes, it is a simple piece of sheet metal. I believe there are several variations on where holes are punched depending on the original application. Held on by the front manifold stud nut and by a special stud on the fuel pump that replaces one of the screws that hold the fuel pump together. I believe that Vintage Power Wagons sells heat shields but don't know of a supplier of the special stud for the fuel pump.

Link to comment
Share on other sites

Here are a couple of pics from my 46-48 Chrysler parts manual. It may not be identical to what a 50 DeSoto used but it gives you a general idea of what your looking for. I would try some junjyards to see what you can dig up or hae one made or make one yourself. It's just flat metal that can be bent into shape

Ply33 is correct in how it attaches.

Joe

post-55506-143142332668_thumb.jpg

post-55506-143142332643_thumb.jpg

Link to comment
Share on other sites

  • 4 weeks later...

This might be way off base, but I had a 51 Imperial that had a ceramic fuel filter inside the gas tank that caused me all kinds of issues similar to yours. Had to remove the tank and bust up the fuel filter to correct the problem. Do not know if your car is so equipped.

Link to comment
Share on other sites

  • 1 month later...
  • 3 weeks later...

I have not gotten into it yet since I've been too busy with my work. My guess it has a lot to do with the poor fuel quality these days (it's at least 5% ethanol). On the other hand, if I remember correctly I did have no problems when I bought this car and drove it home from Sweden. I had a traffic jam in Germany and it did not stall back then. I know the exhaust valves are not sealing 100%. On the other hand: the problem only occurs and worsens when idling in traffic or when turning the car off at the petrol station. And it does seem to help (speed up the restart) when cooling down the fuel line.

I was thinking to isolate the fuel lines with a special sleeve made for cooling purposes on high performance cars, but the aluminum foil-like appearance of such sleeves does break down the authentic look of the car. And since I'm trying to sell it too, that's not a perfect solution too.

Link to comment
Share on other sites

  • 3 weeks later...

I have tried to start my DeSoto since the weather is good again, but I might found what may be one of the culprits. The car wouldn't start at all this time. I've removed the spark plugs and they look old. No damage but just dark brown (no rust). I want to change to new spark plugs but cannot find the exact temperature of the plugs.

The workshop manual says it needs AR8 -> 14 mm thread, .035" gapped. But no temperature. The problem is that I cannot find a conversion table for the AR8 to newer numbers.

The current spark plugs are Champion RJ12C, that would be the same as a NGK BR6S, but I believe they're incorrect, because this is what Rockauto says:

Autolite 306 (resistor), Autolite 295 (non-resistor), Motorcraft SP480.

Do I need resistor or non-resistor and what are other people's experiences?

Link to comment
Share on other sites

If you do not have a radio use non resistor plugs but either will work.

Yes, resistor is to cut down on noise coming out of the radio. At least in the old cars. Maybe on the new ones it helps keep the computers from running amok but that would just be a guess. Depends on how sensitive they are to radio frequency interference.

My last go around the local store did not have non-resistor plugs in the brand and heat range I wanted so, for the first time ever, I put resistor plugs in my '33. Seems like it runs just the same as it always has. So I think the "but either will work" is true.

Link to comment
Share on other sites

I ordered spark plugs but the size was wrong. New ones will be in the shop on Monday. I got another suggestion from someone with an old Mopar: I should fill half the tank with RON98 in stead of only RON95. The latter contains 10% ethanol and is known to be more sensitive to cause vapor lock.

Next week I hope to drive again...

Link to comment
Share on other sites

I ordered spark plugs but the size was wrong. New ones will be in the shop on Monday. I got another suggestion from someone with an old Mopar: I should fill half the tank with RON98 in stead of only RON95. The latter contains 10% ethanol and is known to be more sensitive to cause vapor lock.

Next week I hope to drive again...

Over here in the states we have gas choices 87,89 and 92..(some areas it's 85,89,93) I know a lot of guys and I read a lot of guys having problems like yours. Now the 92 depending on the station (the really cheap stations will dilute with ethanol so more they dilute less taxes they pay, and kills your mileage so more you buy.) has less ethanol and cleaners that are good for the carb. So switching stations and switching grades might surprise you.

There are some guys they get in this crab pot mentality that gas is just gas and low grade (85/87) is just fine and they don't won't to step up the extra $$ but they have no problem stepping up and paying the $$$ to rebuild carbs, fuel pumps etc...when they could have just not had the problem in the first place.

Link to comment
Share on other sites

here's something that might get the car going, take the idle screw out of the carb, either with compressed air or a can of carb clean spray it in the hole, when you're all done with that put the idle screw back in..just screw it in all the way then just back it out three times with the screw driver.

Link to comment
Share on other sites

Over here in the states we have gas choices 87,89 and 92..(some areas it's 85,89,93) . . .

In Canada and the US the numbers on the pump are an average of the RON and the MON. I think most of the rest of the world posts the RON value.

Since RON is typically about 10 points higher than MON that means that a US pump number of 87 is probably close to 92 RON.

Link to comment
Share on other sites

That's right, The US numbers don't match ours. We don't have a lot of choice too; one can buy 95 at every petrol station but 98 is very scarce since no modern car really needs it anymore and it is much more expensive (95 is about $9,20 per gallon where 98 is $9,95 per gallon) so no one buys it anymore. Except for rich people with Ferraris maybe. :P

Link to comment
Share on other sites

That's right, The US numbers don't match ours. We don't have a lot of choice too; one can buy 95 at every petrol station but 98 is very scarce since no modern car really needs it anymore and it is much more expensive (95 is about $9,20 per gallon where 98 is $9,95 per gallon) so no one buys it anymore. Except for rich people with Ferraris maybe. :P

Sounds like they got you coming and got you going:rolleyes:

Link to comment
Share on other sites

Cool, thanks for the wise words. I'll try the starting tip next time for sure! If I cannot get it to fire up with the new spark plugs I'll check and clean the carb (I cleaned it a year ago last time) and the idle mixture screw. Maybe I should look in to refurbishing the starter or buy a new battery too as it does not turn as fast as I think it should (no reference though).

Link to comment
Share on other sites

This is just unbelievable. I refurbished the carb, put in new spark plugs, I know there is spark, I know there is a fuel and air mixture but there is no ignition what so ever. None. Why? How? She doesn't want to be sold I guess.

After 4 months of standing still there is not even the slightest attempt of firing a cilinder. Just crazy...

Link to comment
Share on other sites

I woke up: I'll order points, rotor et cetera from Andy but how do I find out my distributor number? I believe my soto is a late '50's model (other parts on the car like the internal park brake drum suggests that). The distributor has a vacuum pot on the front top if that helps indication. I couldn't figure out the difference with the workshop manual.

Link to comment
Share on other sites

I have had a similar experience on a return trip from a show. I could go a few miles before my car would loose power and then not run at all. It was a hot day and I assumed a vapor lock. Someone else suggested my coil was going bad. They asked if the coil felt hot and of courses I never checked it that day. No one had a 6 volt coil tester so I did just replace the coil and I have never had that problem again.

I also had times where my car would run great and then just quit and not restart until it was towed. Then it would restart and run fine again. That turned out to be a loose wire nut on the back of the ignition key switch.

Just throwing out other ideas.

Link to comment
Share on other sites

Thanks, much obliged! I do have a spare coil too, 6v, only I don't know if it will fit the bracket since it is cylindrical (no bosses) and may be will not fit. I didn't think to replace that yet, how stupid it may sound. I got an order confirmation of Andy Bernbaum so when the parts are in I'll replace them and if that does not work I'll replace the coil too. The replacement of ignition parts is quite regular maintenance so that's never a bad idea. I did notice the distributor cap on the inside had blackish spots on the ignition plug terminals, even some parts where the plastic has severed a little. I cleaned it up a little but this did not help in any way.

Link to comment
Share on other sites

I have had a similar experience on a return trip from a show. I could go a few miles before my car would loose power and then not run at all. It was a hot day and I assumed a vapor lock. Someone else suggested my coil was going bad. They asked if the coil felt hot and of courses I never checked it that day. No one had a 6 volt coil tester so I did just replace the coil and I have never had that problem again.

I also had times where my car would run great and then just quit and not restart until it was towed. Then it would restart and run fine again. That turned out to be a loose wire nut on the back of the ignition key switch.

Just throwing out other ideas.

Back in the 70s I got a '56 VW Beetle as a daily driver. For the first year I had it it would occasionally act like it was running out of fuel. Each time I'd check all wires and hoses are tight. Then I'd pull the air cleaner and look down the carburetor while I actuated the throttle and I could see gas from the accelerator pump. Got gas. Then I'd pull a spark plug and check for spark. Got spark. Hmmm. Got gas, got spark, it ought to run. Get back in and it would start back up. Drove me batty.

Even took it to the dealer who charged a bunch of money but ended up having no clue what the problem was and did not fix it.

Finally, the last time, while I was cleaning up my hands after one of these episodes, I noticed wax on my hands. Wax? Where in the heck in the engine compartment would wax have come from? Looked around closely and found a hairline crack on the coil tower. Replaced the coil and the problem was fixed.

Apparently I took long enough checking the fuel and verifying all the hoses and wires were tight that by the time I checked the spark the coil had cooled down enough to work. So I'd have spark when I checked it. So much for being slow, methodical and always doing things in the same order. :)

Link to comment
Share on other sites

I measured the coil today: A healthy 1.6 Ohm between plus and minus and an okay 6.36 kOhm between plus and high voltage out. There was no sign of leakage.

I have removed the IAT-4004 distributor from the engine, cleaned it and am ready to install the new parts from Andy Bernbaum. I removed everything from the baseplate up, so the weights and springs are still attached as is the shaft.

The workshop manual says I have to lubricate some parts with medium oil, some with light oil and some with grease. Can I use:

- 20W50 classic car oil for the medium one? Single grade oils are hard to come by here, I had a hard time finding 10W for the tranny.

- sowing machine / air tool oil for the light oil?

- EP2 grease for the grease? As with the single grade, distributor grease is really hard to come by (everything here is modern and pointless *no pun intended*).

Furthermore: I could not find with which lubrication I should lubricate the weights and springs and with which I should lubricate the contacts between the base plate and the breaker plate.

Link to comment
Share on other sites

  • 2 weeks later...

If you mean to grease the points cam or points rubbing block use special ignition points grease. You should be able to get a tube at an auto parts store. Use a dab the size of a match head.

If the points have a felt oiler, oil it with 2 or 3 drops of oil. Do not over lubricate anything inside the distributor, it can gum up the points and cap.

Link to comment
Share on other sites

The points do have that felt thingy. So that should be oiled, with machine oil..?

Currently I am trying to remove the inner right wheel well to gap the valves. The exhaust valves are probably not closing enough, at least that is the most likely scenario now.

Link to comment
Share on other sites

If the engine was badly flooded the spark plugs may have gotten coated. When this happens they will not spark until you clean them by sandblasting. Nothing else will clean off the coating.

Here in Canada this usually happens when a car will not start and gets flooded in cold weather. But I have also seen it happen because of a faulty carburetor.

Try a fresh spark plug and see if it sparks, if the plugs are dirty sandblast or replace.

Link to comment
Share on other sites

There is no visible coating. They look completely clean and we're never soaking when I removed them. They have only been in the engine since I upgraded the ignition. So they have never even been really used (no ignition). Could they be invisibly coated? They look like they just came out of the box.

Link to comment
Share on other sites

By the way, when cranking the engine with the spark plugs laying loosely on the head they spark bright white.

Then there is no problem with the ignition. The only possible problem would be, if you did not have the timing set correctly or if you accidentally put the wires on the wrong plugs.

Link to comment
Share on other sites

  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...