Runs until radiator is hot, then shuts off

Asa

Asa

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Not sure how long exactly, but long enough for the thermostat to open and the radiator to get hot enough you don't want to touch it.

Done this a few times, crank the car (usually with a shot of ether to help that crappy gas to catch), she starts up, might have to repeat and feather the choke a few times to get her to hold, but eventually she starts turning over nicely. Let her run for a while and putter around in the garage, after maybe 20 minutes or so she shuts off.

It shouldn't be a fuel issue as the starting fluid does nothing to get her to turn over again, so what could it be?
I'm wondering if my heat sink is not sufficient, but I have run this setup before well enough to drive 20 miles or so, I'm mildly stumped.

I have some superfluous wiring in the system as a rudimentary anti-theft switch, but I could easily remove that. (and, once again, ran it like this quite successfully for a while)
 
Asa":126t45h6 said:
......It shouldn't be a fuel issue as the starting fluid does nothing to get her to turn over again, so what could it be?
I'm wondering if my heat sink is not sufficient, but I have run this setup before well enough to drive 20 miles or so, I'm mildly stumped.
........
Click to expand...

I think you are on the right track looking at that.

Asusual you will have to get it to quit to figure out why it quits.
just pull a plug wire to see if you still have spark.
 
Asa":18jk4hd1 said:
Not sure how long exactly, but long enough for the thermostat to open and the radiator to get hot enough you don't want to touch it.

Done this a few times, crank the car (usually with a shot of ether to help that crappy gas to catch), she starts up, might have to repeat and feather the choke a few times to get her to hold, but eventually she starts turning over nicely. Let her run for a while and putter around in the garage, after maybe 20 minutes or so she shuts off.

It shouldn't be a fuel issue as the starting fluid does nothing to get her to turn over again, so what could it be?
I'm wondering if my heat sink is not sufficient, but I have run this setup before well enough to drive 20 miles or so, I'm mildly stumped.

I have some superfluous wiring in the system as a rudimentary anti-theft switch, but I could easily remove that. (and, once again, ran it like this quite successfully for a while)
Click to expand...

Could the fuel bowl on the carb be getting hot enough to boil the gas and flood the engine, stalling it? This was happening on my Ranchero with a 200 and an Autolite 2-V carb. While driving, you're using the gas much more quickly, and cooler gas is constantly being replenished, ,so it doesn't boil, but at idle you're not using much gas and the gas in the bowl gets very hot.

Bob
 
80broncoman":4s38p1vj said:
I think you are on the right track looking at that.

Asusual you will have to get it to quit to figure out why it quits.
just pull a plug wire to see if you still have spark.
Click to expand...
Yeah, that's always the fun part.
I wonder what I could use for a heat sink, I have a whole buttload of aluminum diamond plate that is a good 1/4 to 3/8" thick. I currently have a piece of 2x8x1/8" aluminum plate in there that I've been using. I'm still not convinced it no longer works, although when I did have her running regularly on that setup it was fall/winter in the DC area, so maybe it was just colder.

62Ranchero200":4s38p1vj said:
Could the fuel bowl on the carb be getting hot enough to boil the gas and flood the engine, stalling it? This was happening on my Ranchero with a 200 and an Autolite 2-V carb. While driving, you're using the gas much more quickly, and cooler gas is constantly being replenished, ,so it doesn't boil, but at idle you're not using much gas and the gas in the bowl gets very hot.

Bob
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Possible, but I doubt it. As mentioned earlier, I would expect to see it try to turn over with the starting fluid.
 
ludwig":3fri2w9x said:
Are you running way too hot due to a lean condition?
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I pretty much have only had her idling, no real driving, so I'm not sure if that changes anything, but the plugs are nice and tan.

Would it make a difference?
 
The idle is one thing; running hot is another. I don't have much to add past that. Mine ran really hot until I got the F/A mix and the timing sorted out.. Seems like you haven't had it out and going enough to really wring it out yet.
 
ludwig":3c7andcv said:
Are you running way too hot due to a lean condition?
Click to expand...
x2

I don't know enough about old gas, but I can assume age doesn't make it stronger. Weak gas can be leaning her out. It doesn't help that sitting, even with a fan, is going to make her run a little hot, and no fresh air from travelling forward means that intake air is getting hot and sparse too. Just seems like a recipe for coziness.
 
80broncoman":18ajmkg9 said:
Be sure to use plenty of heat sink compound be tween
The module and heat sink.
Click to expand...
I used everything in the package that came with it.



I still haven't heard a good reason why the engine itself running hot could become an issue other than the fuel boiling, and since the starting fluid didn't get it to try and start after that I don't think that's the issue. I might need to address it at a later date, but right now I'm just trying to ensure that I can get her to stay running.
 
engine rpm is very low during start, and airflow is very low as a result. That gives the air plenty of time to really heat up and expand, reducing the density of the O2. Theoretically you could get to a point that there isn't enough oxygen to light the fire.

when you cycle, can you smell fuel out the exhaust? If so is it strong or light? Best way to tell is when it's in good shape pop the coil wire and cycle the engine, and smell the amount of fuel cycling without an issue. Then compare.

how does she die when she gets hot? Just cut out, stumble out over how many seconds, or just slow down and stop over how many seconds? Does the smell of gas bump up after she dies?

as broncoman said, check spark as well. Heat related failure of your ignition system is a possibility.
 
Invectivus":2fz80dt4 said:
engine rpm is very low during start, and airflow is very low as a result. That gives the air plenty of time to really heat up and expand, reducing the density of the O2. Theoretically you could get to a point that there isn't enough oxygen to light the fire.

when you cycle, can you smell fuel out the exhaust? If so is it strong or light? Best way to tell is when it's in good shape pop the coil wire and cycle the engine, and smell the amount of fuel cycling without an issue. Then compare.

how does she die when she gets hot? Just cut out, stumble out over how many seconds, or just slow down and stop over how many seconds? Does the smell of gas bump up after she dies?

as broncoman said, check spark as well. Heat related failure of your ignition system is a possibility.
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Theoretically that could work, however I believe that for the engine to get hot enough to expand the air enough to cause it to not ignite, you'd heat the entire system enough to cause the cooling system to fail and have something pop.
Even before that you'd run into other issues though, you'd get warning signs such as metal parts getting red hot.

I'm doing all of this in a garage with low ventilation, no clue if it's pumping gas out after because I can't smell anything but burned hydrocarbons. Because of only having headers on there right now, I can tell that I'm getting a vapor being pumped out though, reminds me of a worn diesel trying to start without the benefit of a glow plug system

Dies abruptly, which also makes me think that it's not an issue of the carb boiling, maybe one cough and then it's done.
 
Yeah, perishing that fast sounds like an ignition issue. Maybe move the coil to the fender?
 
:unsure: X3 As with a few others in above posts. IMOP it's an electrical issue nothing to do with the carb or fuel, something like a transistor / diode or coil is failing or turning off when it gets warmer. Put a test light or volt ohm meter on those parts when cool and after it shut off, you might be able to find it that way. Good luck
 
Sound electrical to me.

Get a can of freeze spray from an electronics store and spray down components until you find the one that lets the engine restart and replace it.

Good Luck
 
69.5Mav":pa080w9n said:
Sound electrical to me.

Get a can of freeze spray from an electronics store and spray down components until you find the one that lets the engine restart and replace it.

Good Luck
Click to expand...
I like the cut of your jib sir, I will try forthwith
 
Latest Hot Rod magazine has an article about a car that won't start when hot. The problems were both electrical and cooling. Specifically, because the engine was running way too hot due to inadequate cooling, the voltage flow was compromised. You might check it out.

On the website, they had another story in September of a fellow's car that wouldn't keep running at road temperature. That one was a matter of the fuel pump location, it being too low and thus it compromised the siphoning of fuel.
 
Snagged a heat sink today from a computer repair store, spent the afternoon fabbing a bracket for it. In the course of building, I generated two questions.

1) One of the posts on my Mallory coil broke, so until I see if I can repair that coil I will use the old coil off my truck. So, question is, does a TFI coil have to be electrically insulated from the body/ground?

2) What do I look for for thermal grease? While at NAPA they pointed out a package of silicone dielectric grease that said it worked for GM HEI ignition modules, but I wasn't convinced enough to buy it.
 
:D Check out the offerings at the computer store.The heat sink grease that they sell is the best for what you want to do.
Good luck.Have fun.Be safe.
Leo
 
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