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Discussion Starter #1
I have a 67 mustang with a 289, c4 trans, and edelbrock 4 barrel carb. After driving car for as little as 15-20 minutes on a hot day it heats up to the h and I either turn it off or it will idle bad then die. It has an oversized radiator full to the top and I just changed the oil. I’m wondering if it has to do with vapor lock or a vacuum or something? Also it tends to not start or crank really slow after shorts drives. This is my only car and I need it reliable for daily driving, anything helps.
 

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Definitely a cooling issue. Two things that come to mind immediately.

1. Could be a water pump issue. While cold, take of the radiator cap. Start. Long in the cap for coolant flow.

2. (My best guess) Could be the clutch on the fan is worn out (if so equipped). Check the fan when engine is cold. Should spin fairly freely. Get engine up to full operating temperature. Shut off. Fan should now not be easy to rotate. Had this very issue on an '89 with a 5.0.

Phil
 

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Do you have an IR temperature gun to check the real temperature? The old gauges are not necessarily accurate. Everything below 220 F is fine. What Thermostat are you running?

Does it overheat while idle? Or only while driving? Overheating at idle is usually an airflow issue. At driving coolant issue. What mixture are you running? 50:50?

Don’t top it off all the way. You need some air in the system.

Not starting while hot could be vapor lock. Do you have a carb spacer? Is the fuel line touching the engine? It could also be the starter is soaking heat and has a higher resistance. Check the ground contact and the battery.
What is your timing?


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Discussion Starter #4
Do you have an IR temperature gun to check the real temperature? The old gauges are not necessarily accurate. Everything below 220 F is fine. What Thermostat are you running?

Does it overheat while idle? Or only while driving? Overheating at idle is usually an airflow issue. At driving coolant issue. What mixture are you running? 50:50?

Don’t top it off all the way. You need some air in the system.

Not starting while hot could be vapor lock. Do you have a carb spacer? Is the fuel line touching the engine? It could also be the starter is soaking heat and has a higher resistance. Check the ground contact and the battery.
What is your timing?


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I do not have a temperature gun but I believe the gauge is right because the car acts like it’s hot when it says it’s hot. I’m not sure what thermostat but I installed it about a year ago so it’s fairly new. It overheats faster while at idle which I know is because I don’t have a electric fan but it still overheats in less than 30 minutes if I am driving. I run 50:50 coolant and it’s not topped off but just near the top, I’ll let some out though if it might need more air. I do not have a carb spacer but the intake came with the carburetor and I thought I wouldn’t need a spacer? The fuel lines not touching the engine but I might reroute it to make it further away from the block. I think I have a ground problem with the battery because the cable gets very hot after I crank on the car a little bit and I’m yet to get it timed which I know is important but it’s just timed by sound right now.
 

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Proper ignition timing, proper mixture and jetting at the carb, the health and cleanliness of the cooling passages, airflow, and using steel lines instead of heat-holding rubber help a lot.
 

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Timing can cause overheating/running hot issue.
 

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It sounds like you have a basic cooling issue somewhere which can be caused by a few things and once it gets hot it then causes the pump gas boiling issue. The boiling fuel makes it hard if not impossible to re-start the engine once it heats up.

I don't have the cooling problem but I do have the fuel trying to boil in the line and carb problem on my F150. I pulled the hard line to the carb and replaced it with stainless braided fuel hose, thermal wrapped the fuel hose and installed that inside a plastic loom. It is just enough to keep the engine going but my idle rpms go up by around 200 once it heats up. My guess is the fuel is hot enough to lean it out some. I should also probably try one of those carb heat shields but my to do list is long and this is a roundtuit deal.
 

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Discussion Starter #9
Please post a picture of your radiator/fan configuration. Something may jump out at us. For example, are you running one of those "racing" fans? Those things are notorious for causing overheating issues. They don't pull enough air at idle.
Please post a picture of your radiator/fan configuration. Something may jump out at us. For example, are you running one of those "racing" fans? Those things are notorious for causing overheating issues. They don't pull enough air at idle.
Please post a picture of your radiator/fan configuration. Something may jump out at us. For example, are you running one of those "racing" fans? Those things are notorious for causing overheating issues. They don't pull enough air at idle.
i wasn’t sure how to reply with a picture so I just posted it
 
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