383 4BBL Overheating while Idle and Driving

[Firstimeclassic]

So I have been battling this issue for a few weeks now. I have done:

-multiple coolant flushes
-washed out the radiator
-replaced the thermostat with a 160 Edelbrock high flow from the 180 that was in there
-installed a high-flow water pump.

Sitting and idling, she continuously rises in temperature up until 230-240F until I shut her off. I have tried driving around to see if airflow helps but it just gets hotter and hotter.

I am currently hunting for a 7 blade straight replacement fan to replace the crappy plastic one I have currently. I am hoping it will go well with my custom shroud and radiator. The rad looks fairly new so I am at a loss here. Is my block maybe plugged somewhere?

 

[69 Sleeper Bee]

1st thing, what car is it in ? And you say you have a plastic fan ? Have you looked at the fluid with the cap off to make sure it is flowing once warmed up ?
I hear other members talk about how ignition timing can effect temp.

 

[pnora]

Get a shroud and the right fan. Maybe the radiator is restricted.

 

[mountain33]

Ive seen other comments regarding the depth that the fan is located into the shroud?? I have a stock 71 RR with a 383 all original rad, fan and never gets that hot. Even when its into the 90s. I know this is crazy and i dont know enough about your fan. Blades facing correctly? I do A/C work and i have seen people install blades incorrectly on evaporators and condensers. Just guessing. Wish i could offer more help

 

[Mark Barnes]

Original motor? Original radiator, what size? How many rows of tubes in the radiator? (Mine had only 2!) What type temp gauge and sending unit, and do you trust it? Have you tested the actual motor surface temps with an infrared thermometer (point and shoot)?
These are all things that I have read on other threads while trying to figure out why MY motor was overheating. All good questions.

 

[Canadian1968]

you also say you have been chasing the problem for a few weeks. Was it running fine before that ????

 

[towtruckAl]

a 180 temp thermo holds the fluid in rad longer for fan and air flow to cool , fan spaceing to rad is also imp too close and you only draw that small area , and proper shroud and fan is also important proper antifreeze also raises the boiling point . I always give a older cast iron motor a good quality rad flush . good luck

 

[Michael_]

you also say you have been chasing the problem for a few weeks. Was it running fine before that ????

Good question, if not:

I hear other members talk about how ignition timing can effect temp.

Was going to write this!
Would check if the engine is tuned properly first especially since:

I have done:
-multiple coolant flushes
-washed out the radiator
-replaced the thermostat with a 160 Edelbrock high flow from the 180 that was in there
-installed a high-flow water pump.

I have tried driving around to see if airflow helps but it just gets hotter and hotter.

I am currently hunting for a 7 blade straight replacement fan to replace the crappy plastic one I have currently. I am hoping it will go well with my custom shroud and radiator. The rad looks fairly new so I am at a loss here.

If timing/tuning doesn't help i would replace that aftermarkt stuff with the factory correct setup.
In my case thats a 26" Radiator with Fan and Shroud. You can find that info on the fender tag/build sheet for your car.
You can lookup the part numbers by using the chrysler parts catalog for your car/year.

restorationradiators.com can hook you up with the correct radiator for your car.
I bought one for my car and i'm very happy with the product and service.

Is my block maybe plugged somewhere?

It's not impossible but except the car has been running great until recently i suspect its your aftermarket radiator. Could be wrong, though.

 

[#41]

Are you sure the gauge is right? Is it boiling? Might want tot get a cheap thermal gun and verify that your gauge is not off.

 

[Demonic]

Do a compression test. Hot at idle is the fan or shroud having problems. Hot at speed or all the time is a dirty radiator.

Your radiator is dirtier than you think, usually.

 

[Wietse]

I would first double check the temp gauge is actually telling the truth.
Changing thermostats to a lower temp version is not going to solve the problem and you should go back to a 180* once you got it sorted.
At whatever temperature the thermostat opens does not help in any way if your cooling circuit cannot dissipate the heat, and will cause it to overheat anyway.

Seems like yours is overheating all the time and also excessively, you mentioned you got a custom radiator, any more details on this? brand/type/size?
Since it overheats as well while driving i would say that the radiator itself is likely under rated for your application.
If only at idle, your fan and shroud start to become important as this is the airflow factor (CFM) that the radiator will get for cooling at a standstill.

 

[Don Frelier]

Well almost worthless....

 

[BLK 68 R/T]

Lower radiator hose collapsing once it gets hot. Does it have a spring inside? I would check that’.

 

[bc3j]

My stock 383 N code motor never gets hot. It’s an AC car with a factory six bladed water pump impeller, 26” stock radiator, 195* T stat, 5 blade fan with clutch and shroud, 50/50 anti freeze. My timing is set by ear turning the distributor till the idle peaked then it ran rough then backed off. Then I put a timing light and checked it at 21* initial and left it there. Runs and starts fine. Fan blade width is half under and half outside the shroud with the tips 1/2” away from the shroud. A laser thermostat reading on a hot day is 198* at the T stat housing. My temperature gauge only reaches the lower part of the normal range arc. Hope this helps.