Having an overheating problem on my 340 when I get up to cruising speed. Running 355 gears so I am running at about 2600-2800 RPM or so. Stays cool at idle. Have the correct radiator and a shroud with a 7 blade flex fan and 180 thermostat. Heater is not connected. Installed a push type elec fan too but it helped only slightly. Could the water be going through the radiator to fast to cool down at rpm? Anyone had this problem??
Overheating at cruising seed
- Thread starter 71Demon
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sixpakmopar
sixpakmopar
get rid of the flex fan and put the correct clutch fan back on the car
demon seed
The Original Demon Seed
First thing I'd check is the thermostat or even replace it with a high flow it may be sticking, they're just a better design than the disc type IMO. Did you say that you added the electric after having cooling problems at highway speed because with the flex fan and electric you may be restricting the flow of air through the rad. at highway speed. Also with a good shroud, fan and radiator even idling around town you shouldn't need 2 fans unless of course you're pushing a pile of HP. Usually if you've got a plugged rad or engine cooling passages the overheating problem will surface more when idling than at speed, I did say usually. Yes if the coolant is flowing to quickly through the rad there will not be enough retention time for the coolant to give up it's heat to the core but this sometimes happens when someone removes the thermstat thinking that'll help a cooling problem. :-D
'64 Cuda
Well-Known Member
Do you have a spring in your lower radiator hose?
demon seed
The Original Demon Seed
Yes, it needs the spring to prevent collapse.
1wild&crazyguy
Banned
it's not flowing/cooling cause the rad is plugged or the rad cap is not holding pressure.
You could almost run with no fan on the freeway at all due the amount of air that will make it's way through un coaxed.
A time when this is not possible is when the rad core is plugged/too low capacity/or the cap let the pressure escape and it begins to boil.
You could almost run with no fan on the freeway at all due the amount of air that will make it's way through un coaxed.
A time when this is not possible is when the rad core is plugged/too low capacity/or the cap let the pressure escape and it begins to boil.
cudamark
Well-Known Member
As long as it's a quality flex fan, that won't be the coolong problem(except that it will eventually grenade and send shrapnel through the hood!). As mentioned, you can run all day long on the freeway without a fan at all because there is enough ram air coming through the grille. Assuming the radiator is not plugged, I suspect it's either a collapsing lower hose or a water flow problem caused by a mismatch of pulley diameter and/or number of impellers on the pump. I've seen many of these when an engine is converted from A/C to non-A/C or an engine that's been pieced together from misc parts from a variety of sources. Won't be the cap either.....it doesn't control the temperature....it just helps keep the coolant from boiling. (putting the system under pressure, raises the boiling point). Another possibility is too much antifreeze. Pure antifreeze isn't a very good coolant so make sure you have a good 50% mix with distilled water.
Mark
Mark
damnimcooltom
Too Cool For School
When you say "overheating problem," what do you mean? Is it puking coolant out, or do you actually have a temp gauge that tells you what the actual temp is?
Is the radiator sealed at the top and bottom to force air through it on the road, or can it escape over and under it? Where is your timing set at full advance?
There are a ton of things that can lead to heat issues. It seems that we're all leaning towards a plugged radiator as our first guess.
Is the radiator sealed at the top and bottom to force air through it on the road, or can it escape over and under it? Where is your timing set at full advance?
There are a ton of things that can lead to heat issues. It seems that we're all leaning towards a plugged radiator as our first guess.
Brought it up to operating temp and then brought the rpm to about 2800 and no colapse in the lower hose. So....I am assuming the rad is partially plugged or the water pump is wrong. I am assuming the more impellers it has creates more cooling and water flow? Yes? How many impellars should I have. I guess the other possibility is what you said about the pulleys. I am running the march pulleys.
Don't kill me on this, but I've seen it. Some flex fans at speed will "flatten out" and actually block airflow. (That's just before they grenade and put a hole in your hood).
Is it a stock water pump or is it an Edelbrock supplied by March? I've had troubles with some of the Eddy pumps supplied with March pulley kits moving too much water and causing some grief.
Is it a stock water pump or is it an Edelbrock supplied by March? I've had troubles with some of the Eddy pumps supplied with March pulley kits moving too much water and causing some grief.
turbodart68
Well-Known Member
X2 on this one. I have experienced this myself. Once I put a Mopar Performance clutch fan kit on it, it ran cooler at speed. The fan will flatten out and create a blockage, especially with a proper shroud.
inkjunkie
Well-Known Member
Had this happen also. Whose brillant idea where those flex fans anyway?
JR
Pissed off senior member.
No matter what the problem is I would still put a spring/coiled up coat hanger in the bottom hose.
guzzimike
Well-Known Member
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IMHO, 200 is not "Hot"..
If it gets to 220+, that's when should you start to worry
I run my 383 at 200 - 210F all day long on the street and Freeways here in SoCal...
I have 3.91 gears and a New-Old-Style Brass/copper radiator from a '73 Wagoneer (400ci engine). 160F thermostat.
I use distilled water and "Water Wetter" in my cooling system.
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I am being told a 195 thermostat will cure the problem. They are saying it will be able to regulate the temp better because the 180 is just staying open all the time once heated up. The 195 would cycle and therefore allow cooler water to stay in the radiator until needed. They also say the 195 is the factory correct one. True...anyone??
I am now having this problem I realized it a couple of days ago, I don't understand what the problem is everything is fine and going well then out of no where I realize that I'm having an overheating problem and I am not sure if it has to do with the Thermostat or not.
Johnny Dart
Well-Known Member
Stick with the 180.The 195 will not affect the temp.All it will change is the time to get to the same temp.New cars run 195 thermostats.They run hot. Hotter running car,cleaner burning car.
200 is not hot.
Where is your timing ?
New engine ?
Radiator good ?
Running lean ?
All these will make a car run hotter than it should.
But 200 is not hot.
Little tip. Although illegal in california,I run no front plate on my 70 Dart.
It gets some really good air without it.
pntastar69
Well-Known Member
Timing, timing, timing. Been there, done that.
WildCat
Well-Known Member
What march Pulleys?
View attachment Pulleys.jpg
Larger March Serpentine drive about 7" underdrive
smaller March about 5 3/4" standard
View attachment Pulleybe4.jpg
large underdrive
View attachment pulleyaft.jpg
standard drive
I have had a heating issue with mine. I have AC 6 blade water pump, plan on changing it to a 8 blade this winter.
good luck finding your issue
green1
Well-Known Member
Radiator.
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