New Member

[ActionGrant]

Hi! I've been lurking for a while, and decided to finally sign up so I could ask some questions. I have a 1951 DeSoto Custom, with the 251 Flathead 6 and the 3 speed fluid drive transmission. I bought this car in August of 2009, and haven't done too much work to it.

I rebuilt the brakes, cleaned the water distribution tube, replaced the water pump, and replaced the radiator. Its been out on the road a decent bit since then, but I've recently started having trouble getting it started. I had a mechanic take a quick look at it, and he said he suspected that it was the auto choke / high idler switch. I'm kind of a noob, so I'm trying to learn as I go, but any suggestions would be greatly appreciated!

I'll throw up a picture too. I realize that this forum is mostly Plymouth folks, but I believe the engine is really similar, so hopefully you'll have some tips for me. Thanks!

[David Strieb]

Welcome to the forum, nice DeSoto..What kind of starting problems are you having. If it's still 6 volt, make sure the + side of the coil goes to the distributer or the current is flowing backwards in the ignition system and producing a weak spark. Make sure ALL your grounds are good, and use heavier gauge wires suited for 6 volts on everything and check to make sure all your connections are clean and tight in the engine compartment and under the dash.

[Niel Hoback]

Thats a really good looking car there. Did you change the battery cables? They have to be very heavy gauge, not those wimpy little 12 volt wires you get at Wal-mart in order to work. Check you points if you haven't been there yet. Clean the plugs too. I wish I could just run over there and do the simple stuff!

[ActionGrant]

Lol you're welcome to come by! I have new spark plugs, I left the battery cables alone because they look solid, and they do look like a heavier gauge than 12 volt battery cables. The points were really wide, so I filed them down a bit. At this point, I suspect it is my ignition coil, I'll throw a new one on there tomorrow and see how it goes.

[Niel Hoback]

What did you set the point gap at? Anything like .017?

I'm going your way May 15, but it will be in a 747 on my way to Budapest.

[Andydodge]

Hey, that looks like a nice, tidy Mopar, DeSotos are fine on here too, I have a 41 Plymouth Coupe and 40 Dodge Sedan, both rodded here in Australia and these guys still talk to me........lol.......seriously tho there are some extremely nice and knowledgable people on this forum, Welcome from Oz.......Andy Douglas

[Greenbomb]

Welcome to the group. The ol' Desoto looks like it should be a real cruiser. That's some interesting looking paint on the front end. Anything special or just the way the light hits it? Let us know what you find to cure your problem. I'll just reiterate what everyone else has said to look for.

[ActionGrant]

The paint on the front end... riiight... it only looks funky because it is in the rain in that picture, the hood is actually primered. As for the other suggestions, the ignition coil is wired up correctly, but I think that it may still be the source of my problem, as it wasnt starting because the dipstick had rotated into it and was shorting it out, and I suspect that this may have damaged it. I'm picking up another ignition coil tomorrow morning, and I'll drop that in and see if it makes a difference.

[Flatie46]

Nice car welcome to the fourm. Hope you get the bugs worked out soon.

[P-12 Tommy]

Welcome Action! Nice DeSoto.

Tom

[ActionGrant]

Ok, so replacing the ignition coil solved my problems!

..with starting. When idling, the car overheats like crazy. I realize this is normally an issue, but it seems to overheat more quickly than it should, even just stoping at a stoplight I'll see the temps creep up past the third dot on the sensor... I dont know what the issue could be! I replaced the stock radiator with a three row aluminum rad (because it was cheaper than recoring the original, clogged one), I have a new water pump, and I even pulled the water distribution tube to clean it up and make sure that was ok. Any suggestions?

[Plymouthy Adams]

what thermostat you running..they serve more than just a haet up prupose..they also control the enchange of heat from the block to the readiator anf removal to the radiator...do you have air leaks about the radiator support that could be pulling air by the fan NOT thourgh the rediator and thirly..check that timing...a bit too high, runs greats, temp does go up..

[martybose]

With the radiator replaced I'm not sure if you are running pressurized or not. If you aren't pressurized, I would suggest carrying a candy thermometer with you, and the next time your gauge registers high pull the car over, leave it running and stick the thermometer in the top tank of the radiator and find out what the temperature really is. I found that my temp gauge read about 25 degrees higher than actual temp.

Marty

[ActionGrant]

it is still pressurized, it actually came with a 16 lb pressure cap rather than the 4 lb stock one. Also, regardless of whether or not my temperature gauge is a bit inaccurate, the car overheats to the point where the engine will turn off. It doesnt start knocking or pinging (like it would were the coolant boiling), it just overheats and turns off. When it does this, it smokes quite a bit from the crank case, so I'm rather concerned at this point...

[Niel Hoback]

Wow, that sounds more like a lack of oil or oil pressure than coolant. I would worry about oil passages being plugged. Did the car sit unused for a long period of time? Could you have loosened up some sludge and plugged a passage? What does you pressure gauge show?

[aero3113]

Did you try pulling any core plugs? The block can get gummed up pretty bad from all the years of service.

[ActionGrant]

Pressure gauge shows nothing when the car is off, then it goes up to around 35 when just idling when its warm, and 60 when I'm on the gas.

[Niel Hoback]

Thats an excellent sign. Have you checked the temp at various locations on the block and head when this happens? Get one of those cheap radiant thermometers at someplace like Harbor Freight and see where its hottest. Maybe you can spot a blockage somewhere. Good Luck to You on that, its very worriesome.