340 Running Temp

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MOPARJ

MOPARJ

What can I upgrade now?
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When cruising my 69 Cuda, the temp will be 200 in the city and will rise to 205 while moving and upwards of 210-212 when cruising at 2800 RPM on the freeway with 3.23 gears. The cap was bad, as it was pushing water. That solved that issue, but the temp is the same. I would have to guess the pump is ok, as the belts are tight and water seems to be circulating. I replaced the thermostat a year ago and with the cap off, I can see slight movement of the coolant, signifying that the stat is working. Its a 185 unit. The radiator seems to be ok.

Are these temps too high? Would going to a 175 stat help?
 
Thats really not that hot but like most I feel better if it stays around 185-190. Judging by your zip code your in Cali so your going to run warmer because of the weather. Have you tried flushing the system out good ? Check your timing and carb and make sure they are set right also.
 
If a motor runs warm while idleing or slow speed (under 35mph) it is a fan/ shroud problem. If a motor runs warm at speeds above 35mpg and has a steady rise in temp then the radiator is too small. I would say that you need a bigger radiator being you cooling problem is more speed related. Granted if your motor was running on the lean side it would build heat easier but if it runs good and doesn't surge then that is not the issue.


Chuck
 
MOPARJ

Are you running your fan with a clutch? If so make sure that it is working properly. I had a friend who had one on a Cuda 340 that was bad in the sense that it wasn't turning the fan fast enough at low speeds to cool the radiator. At cruising speeds the temp would come down slightly. Ended up the jel inside the clutch was breaking down and not flowing outward as the speed of the engine increased to make the fan turn faster. Changed it out and the problem went away.

Something to check out!
 
340mopar said:
If a motor runs warm while idleing or slow speed (under 35mph) it is a fan/ shroud problem. If a motor runs warm at speeds above 35mpg and has a steady rise in temp then the radiator is too small. I would say that you need a bigger radiator being you cooling problem is more speed related. Granted if your motor was running on the lean side it would build heat easier but if it runs good and doesn't surge then that is not the issue.


Chuck
Click to expand...
Chuck,

Its the stock radiator for a 340. The motor is not heavily modified, just basically stock 70 340 w/ X heads. It doesn't ping, so I wouldn't feel that the timing was too advanced. Also, the carb is not lean. The fan is tight and take s a little bit of a twist to spin is by hand. It stops turning immediately after the motor is shut off. BTW, it is the clutch type.

It does not have a shroud on it, and trying to find one for cheap is next to impossible it seems!! :angry4: The oil doesn't seem to show signs of overheating, or the plugs. The pressure when hot is 35-40 psi at idle, 60 psi at 1300 RPM, and 65-70 psi above that when warm.

Thanks for any addtional input.

-Justin
 
I wasn't trying to be a smart ***, I saw that someone on this forum actually did bolt on their fan backward. :pirat:


You mention only slight movement of the coolant when the cap is off. When 185 degrees is reached, you should see a virtual torrent of coolant once that stat opens. Have you checked for this? BTW, we had another member who found a dead mouse in his radiator.
 
ramcharger said:
I wasn't trying to be a smart ***, I saw that someone on this forum actually did bolt on their fan backward. :pirat:


You mention only slight movement of the coolant when the cap is off. When 185 degrees is reached, you should see a virtual torrent of coolant once that stat opens. Have you checked for this? BTW, we had another member who found a dead mouse in his radiator.
Click to expand...

Ramcharger, I didn't think you were a smart ***....I respect all of you guys
(and gals...) for the help you give me. Unless its a direct target on my ***, I won't snap back. Lol.

As far as the coolant flow in the radiator, its not a torrent and from what i can remember on other radiators is that you can see the top of the core when its flowing. I cannot see that. It still has water and it actually stays right around the neck of the radiator. There is not a ton of movement. Is this the pump or thermostat?
 
MOPARJ said:
Ramcharger, I didn't think you were a smart ***....I respect all of you guys
(and gals...) for the help you give me. Unless its a direct target on my ***, I won't snap back. Lol.
Click to expand...
In that case I wouldn't blame you a bit! LOL!

If you have a coolant thermometer, open the cap, drop in the thermometer, fire up the car and wait till it hits 185. You should see a sudden rush of coolant. If not, I would pull the the stat completely out (after it cools down, LOL!) fire up the engine and see if the coolant is moving briskly. If not (but it most likley will be), you have a blockage or pump problem. If it is, replace the stat again.
 
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