Trying to determine over heating issue with 383

[Fish Tale]

I have a stock 383 4bbl, automatic with A/C that has an overheating issue and was hoping to get some feedback as what might be the cause. 

On a fairly warm day (80 to 90 degrees), after driving say 15 to 20 minutes, the temp gauge starts to climb.  When I get home, it basically boils over once I turn the car off.  Now on a cool day (early morning say 50 + degrees), after driving 15 minutes, the temp gauge moves up slightly and doesn't boil over when turned off.  I have yet to run it longer to see if it does eventually boil over.

Now could this be a plugged radiator, water/coolant flow (water pump), or thermostat issue?  Or a combination?  I have thought about switching over to the Evan's waterless coolant system but want to figure this overheating issue out first.

Any help would be appreciated.  Thanks.

[AARuFAST]

Stat with clutch fan if  you have one.
with engine off.  spin the fan.  If it spins more than one and one half turns freely it needs replaced.
If you have a exhaust heat riser start car and check right rear exhaust.
If those check out ok do thermostat.

[jhaag]

So you are the same guy with the bad heater core in the other thread? If your heater core is rotten, your radiator may be as well. Sounds like you need to have your complete cooling system checked. Is the radiator original? Has it ever been checked? If it has some age on it pull it out and take it to a radiator shop. Have it cleaned and tested. Replace the thermostat and radiator cap. Try this or give more info on the condition and age of the cooling system components and what/when/why you started having problems.

[mopar jack]

sounds like you are over filling the radiator and when you shut it off the water expands and goes out the over flow. If your radiator core is plugging you should be able to see some of the core tubes with the cap off and see if there is a lot of crud on top of the tubes. It might just need a simple clean and rod out though I think most shops will just change the core.

[Racer57]

Check your timing also.

[Fish Tale]

Thanks guys for the feedback.  I will need to do the checks that were suggested.

Yes, my heater core maybe going bad so radiator may also be on its way.  I've only had the car less than a year so the cooling system components are unknown to me.  If I need to replace the heater core, might as well get the radiator tested and cleaned.

Any good recommendations on replacement heater cores, thermostats, and radiator caps?

[Chryco Psycho]

Does it heat more or faster  running steady on the highway or more in stop & go traffic ?
 Stant for rad caps 16 lb & thermostats 180*   , available from Rock Auto

[Racer57]

Btw, you do not have to have a heater core. I turn off the inlet side of mine during the summer.

[Fish Tale]

Does it heat more or faster  running steady on the highway or more in stop & go traffic ?
 Stant for rad caps 16 lb & thermostats 180*   , available from Rock Auto

It over heated when driving through streets with stop signs/lights in hot weather.  So far only driven the highway when it's been cool.

[solarguy]

Is there a shroud on the radiator? 

[Fish Tale]

Is there a shroud on the radiator?

Yes, there is a shroud.

[Chryco Psycho]

overheating at low speed can be problems with water or air flow ,bad thermostat or plugged rad either water or air flow  ,  thermo fan clutch not locking up , fan bolted on backwards  , even just flushing the rad out at a car wash flowing backwards may help the rad flow , but dropping it off a at rad shop is obviously better although you may end up replacing the core if it is still original .