Help! Running hot

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DPCPaintguy

DPCPaintguy

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74 Scamp 360, Aluminum radiator, new 17" flex fan spaced 1" from the radiator, new 185 thermostat and 16psi radiator cap. I can't seem to drive the car more than 5 miles without it getting into the 210 degree range, has not overheated but i do not take the chance running it any hotter. Radiator seems to be flowing when cap is off. I have replaced the simple parts, is it possible it could be the water pump or radiator? I do not have a shroud for the radiator/fan but would it really make a 20 degree difference if i installed a shroud? Thank you in advance all for your suggestions. I really would like to drive the car farther than 5 miles.
 
Does this only occur at road speeds, in town driving or idling? Do you have the hood to radiator seal installed? Where's your timing sitting at initial and full mechanical advance? Is the car running lean? How do plugs look? What gauge are you measuring by? Not being a butt, there's a whole lot of things that play into these types of issues, just trying to pull a little more info.
 
Get rid of that flex-fan
you need A big steel fan off a 73 teenerDart with A/C. Then throw away the clutch it comes with and get yourself a HD thermostatic fan clutch. That fan will need a matching shroud, but you can leave the shroud for last if you have a 220* or less cam.
And finally install an anti-cavitation plate on the water pump impeller.
Now you will be able to run a 195* stat, on the hottest days, in a parade even.
You can, of course ignore the advice like so many others, and keep on keeping on.
One thing I can tell you, is the above system with a 43 year old 26" teener A/C rad keeps my 367 at exactly 205*, no mater what. She goes 93 in the 1/8 at 3650 pounds. You can figure out how much power that might be.
I can also tell you that it makes absolutely no difference what my timing is or how lean I run the carb. Or what gear I am running for that matter.How fast or how slow or whatever. It runs exactly 205.
 
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Thank you for the suggestions! It has me very frustrated. I purchased the car not knowing the history or the current issues.
 
So just to be clear, you just bought this car and since you bought it it has run that hot and so far u have replaced the thermostat and radiator cap? If that is the case I would check a few things, 1; how's the heat? If the water pump was failing, Likely the heat would be poor. 2; when it is running hot, how do the radiator hoses feel? Are they burning up too? Also do u have one of those laser thermometers to determine that the engine is in fact running that hot and you don't just have the wrong sender for the temp gauge. 3; when it's running hot, feel the air the fan is pulling thru the radiator, it should be really hot! If not, perhaps the radiator has some clogged passages and is only flowing on the sides. And finally, does the engine ever cool down with certain driving types like higher speed with lots of air flow across the radiator? Keep us posted with as much info as possible and we will do our best to help!
 
You need more airflow.

Please do a search for "overheat". and read the dozens and dozens of posts every spring/summer about your probs, and how to cure them.
 
- What aluminum radiator do you have? Their cooling abilities vary all over the map.
- And what flex fan brand/model?
- And as asked in post #2, under what conditions does this occur? In slow traffic in town, or at highway speeds? This answer is important in pointing to the right solution.
- Do you have a good seal between the rad and the core support, and between the core support and the hood?

And yes, the lack of a shroud WILL make a big difference if the overheating is in slow driving/idling conditions.

You gotta help us to help you, with more info.
 
AJ/FormS said:
Get rid of that flex-fan
you need A big steel fan off a 73 teenerDart with A/C. Then throw away the clutch it comes with and get yourself a HD thermostatic fan clutch. That fan will need a matching shroud, but you can leave the shroud for last if you have a 220* or less cam.
And finally install an anti-cavitation plate on the water pump impeller.
Now you will be able to run a 195* stat, on the hottest days, in a parade even.
You can, of course ignore the advice like so many others, and keep on keeping on.
One thing I can tell you, is the above system with a 43 year old 26" teener A/C rad keeps my 367 at exactly 205*, no mater what. She goes 93 in the 1/8 at 3650 pounds. You can figure out how much power that might be.
I can also tell you that it makes absolutely no difference what my timing is or how lean I run the carb. Or what gear I am running for that matter.How fast or how slow or whatever. It runs exactly 205.
Click to expand...
Thank You for the information!
 
jonnydart440 said:
So just to be clear, you just bought this car and since you bought it it has run that hot and so far u have replaced the thermostat and radiator cap? If that is the case I would check a few things, 1; how's the heat? If the water pump was failing, Likely the heat would be poor. 2; when it is running hot, how do the radiator hoses feel? Are they burning up too? Also do u have one of those laser thermometers to determine that the engine is in fact running that hot and you don't just have the wrong sender for the temp gauge. 3; when it's running hot, feel the air the fan is pulling thru the radiator, it should be really hot! If not, perhaps the radiator has some clogged passages and is only flowing on the sides. And finally, does the engine ever cool down with certain driving types like higher speed with lots of air flow across the radiator? Keep us posted with as much info as possible and we will do our best to help!
Click to expand...
The heat works fine and runs hot, i have a laser thermometer and have measured the coolant withe cap off so i can see it flowing and had readings in the low 200's and climbing. Hoses get very hot also. I does not cool on highway actually keeps climbing. I have been told by several people i need to get rid of the flex fan and get a steel fan with a shroud on it and see what difference that makes. Thanks again for the help.
 
Dubob said:
Does this only occur at road speeds, in town driving or idling? Do you have the hood to radiator seal installed? Where's your timing sitting at initial and full mechanical advance? Is the car running lean? How do plugs look? What gauge are you measuring by? Not being a butt, there's a whole lot of things that play into these types of issues, just trying to pull a little more info.
Click to expand...
This occurs at both highway and idiling, i do not have a hood to radiator seal. I do not know the timing but car runs great and plugs are clean. Measuring by mechanical gauge inside car and laser thermometer. Thanks for the feedback
 
If it also heats at speed that is a different issue. But my earlier post will cure that too.At speed , the fan is no longer the prime air mover. Air is being rammed through the rad by the vehicles forward motion. The shroud is also no longer required. Now you are looking at two or possibly three other things. Now you are again looking to see that the rad can actually shed the heat, and that the water is properly circulating.
That points to the #1) thing, the anti-cav plate and 2)the hoses,specifically the anti-collapse spring in the lower hose.
The third contributor here is the core-support seal to the hood. Without it air can be rammed over the top of the rad to enter the underhood area and make it difficult for the hot air coming through the rad, to leave. But I was never able to really prove that at 65 mph either.
A fourth contributor is if the carb is sucking hot underhood air. This is one of those ugly run-away theories. It goes like this; hot air coming through the rad enters the carb, and the heat gets transferred to the A?f as well as the intake, and the head etc. The hotter theair gets coming out of the rad, the hotter the air goes into the carb, and the cycle grows and grows. Along the way the heated air loses density and the carb goes lean,and the engine runs hotter cuz of that too. And again the hotter the air, the leaner the mix. Now along comes MR Sparky and and tries to light off this lean mixture , but he got to the party late cuz this leaner mixture wants to be lit off earlier. So now with the late start. the fuel may not have finished burning by the time the exhaust valve opens so it continues to burn in the manifolds or headers. Well that just drives the underhood temperature up. So pretty soon you have this little run-away nuclear reactor going on under the hood. Anyway, that is the theory.
A fifth contributor here might be late timing, but I have never been able to prove that one way or another. I have a dash-mounted, dial-back timing device, that can alter the timing from the drivers seat. It has a range of 15 degrees. It makes absolutely no difference to my running temp at speed with the timing jacked any which way, within the limits of the tool.

I can tell you that getting fresh cold air into my carb cured a lot of ails. But I am running aluminum heads. a minimum water temp of 205*, and TTIs. These guys put a lot of hot air under the hood. An awful lot!
But again, the primary thing at speed is to be sure the rad is seeing plenty of cold air ramming through it, and plenty of water circulating through it. BTW the flex fan turns into a wall when the blades flex to flat,heehee
 
AJ/FormS said:
If it also heats at speed that is a different issue. But my earlier post will cure that too.At speed , the fan is no longer the prime air mover. Air is being rammed through the rad by the vehicles forward motion. The shroud is also no longer required. Now you are looking at two or possibly three other things. Now you are again looking to see that the rad can actually shed the heat, and that the water is properly circulating.
That points to the #1) thing, the anti-cav plate and 2)the hoses,specifically the anti-collapse spring in the lower hose.
The third contributor here is the core-support seal to the hood. Without it air can be rammed over the top of the rad to enter the underhood area and make it difficult for the hot air coming through the rad, to leave. But I was never able to really prove that at 65 mph either.
A fourth contributor is if the carb is sucking hot underhood air. This is one of those ugly run-away theories. It goes like this; hot air coming through the rad enters the carb, and the heat gets transferred to the A?f as well as the intake, and the head etc. The hotter theair gets coming out of the rad, the hotter the air goes into the carb, and the cycle grows and grows. Along the way the heated air loses density and the carb goes lean,and the engine runs hotter cuz of that too. And again the hotter the air, the leaner the mix. Now along comes MR Sparky and and tries to light off this lean mixture , but he got to the party late cuz this leaner mixture wants to be lit off earlier. So now with the late start. the fuel may not have finished burning by the time the exhaust valve opens so it continues to burn in the manifolds or headers. Well that just drives the underhood temperature up. So pretty soon you have this little run-away nuclear reactor going on under the hood. Anyway, that is the theory.
A fifth contributor here might be late timing, but I have never been able to prove that one way or another. I have a dash-mounted, dial-back timing device, that can alter the timing from the drivers seat. It has a range of 15 degrees. It makes absolutely no difference to my running temp at speed with the timing jacked any which way, within the limits of the tool.

I can tell you that getting fresh cold air into my carb cured a lot of ails. But I am running aluminum heads. a minimum water temp of 205*, and TTIs. These guys put a lot of hot air under the hood. An awful lot!
But again, the primary thing at speed is to be sure the rad is seeing plenty of cold air ramming through it, and plenty of water circulating through it. BTW the flex fan turns into a wall when the blades flex to flat,heehee
Click to expand...
Thank You very much for the information, since the last post i have removed the radiator to have boiled out and checked to ensure its flowing properly. I also have removed the existing water pump and flex fan and have a new replacements ordered, i did discover the lower hose did not have an anti collapse spring so i will be replacing that also. The heat theory is very valid as it gets very hot under the hood, i have hooker headers but will also be removing them in the future due to under car clearance issues. Once again Thank You for all the insight. I will post again when i get it all back together, hopefully this weekend.
 
Before you ditch those headers, Have you given any thought to the 1.03 Tbars and maybe a bit stiffer shock action? The 1.03s are not too stiff for street duty. I drove my 68 Barracuda over 125,000miles with those bars in there, and most of those miles were as a DD.
 
i had a vehicle that ran 200 - 205 consistently.Although acceptable i made the usual changes to try and lower the temps.I eventually replaced the temperature gauge with a more pricy unit and from that point on the engine ran 185 - 190.
..and yes i checked temps with an infrared heat gun...those things are not accurate.
 
While you have the radiator out, try to flush the block. My /6 ran too hot until I removed a bunch of rust scale and sludge from the bottom of the block. If the block was flushed during a recent rebuild, ignore this suggestion.
 
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