Overheating in traffic - radiator shroud?

[michiganhotrod1]

Hello;
I have a 70 Challenger R/T with a restoration to mostly stock spec about 10 years ago, everything done. The engine was completely rebuilt with everything new, radiator recored,, etc, etc. Runs well overall. Has a new fan clutch and stock R/T fan blade.
It runs hot in traffic and low speed but cools down at speed. I know the stock guage is a guess at best, but it does loose a little coolant once it's parked.
I am looking at the original radiator shroud and it apprears warped, and does not match the radiator well.
Could this be a cooling problem?
Can the shroud be heated and straightened out, or is the old credit card going to be hit again; it appears Mancini Racing has a stock replacement.
Amy suggestions are welcome.
Mark

 

[Challenger RTA]

Could be a shroud problem. Check to see if the thermostat is stuck open.

 

[moparlee]

What do you call hot? Put another gauge on it to see what it is actually reading. Also you have a 15# cap, should be a 16.

 

[Deathproofcuda]

If you car is loosing coolant when parked, it's probably because you are overfilling it. It should be filled to just cover the tops of the fins, with the upper tank left empty to allow expansion. You don't need to fill it to the base of the cap like newer cars that use a separate expansion tank.

When you say "with a restoration to mostly stock spec", does that include having the timing set to the factory spec? 1970 factory timing specs were fairly retarded for emissions purposes, but those retarded specs also increase engine operating temps. If you are running at factory timing specs, your engine will be happier, peppier, and cooler with some added ignition advance.

 

[Ricks72Chlgr440]

Hello;
I have a 70 Challenger R/T with a restoration to mostly stock spec about 10 years ago, everything done. The engine was completely rebuilt with everything new, radiator recored,, etc, etc. Runs well overall. Has a new fan clutch and stock R/T fan blade.
It runs hot in traffic and low speed but cools down at speed. I know the stock guage is a guess at best, but it does loose a little coolant once it's parked.
I am looking at the original radiator shroud and it apprears warped, and does not match the radiator well.
Could this be a cooling problem?
Can the shroud be heated and straightened out, or is the old credit card going to be hit again; it appears Mancini Racing has a stock replacement.
Amy suggestions are welcome.
Mark

Mark,

Lack of low speed cooling is often related to many things. The shroud you have definitely needs to be replaced. Have not seen one deform like that, but it does need to hug the radiator to prevent airflow circumventing the intended flow through the radiator. Engine timing is one to look at, as mentioned. Another is water flow. You'll want to ensure you have a high flow thermostat, like one from Stewart Components. The "high flow" units from other manufacturers are often not. Having a high flow water pump is also a big help. I've had excellent results from a Flow Kooler unit. If you open your radiator cap and look at the inside; is it completely clean where you can easily see the water passages in the core tubes, or is there visible buildup?

 

[Xcudame]

You can't go wrong with parts from Mancini! Great out fit and one of the original Direct Connection ( before Mopar Performance) shops! New shroud, check your timing and make sure your cap and thermostat are working properly. Yes, it's going to heat up in traffic, no way around that! Think about an overflow tank and corresponding radiator cap!

 

[Olacmot]

Hello;
I have a 70 Challenger R/T with a restoration to mostly stock spec about 10 years ago, everything done. The engine was completely rebuilt with everything new, radiator recored,, etc, etc. Runs well overall. Has a new fan clutch and stock R/T fan blade.
It runs hot in traffic and low speed but cools down at speed. I know the stock guage is a guess at best, but it does loose a little coolant once it's parked.
I am looking at the original radiator shroud and it apprears warped, and does not match the radiator well.
Could this be a cooling problem?
Can the shroud be heated and straightened out, or is the old credit card going to be hit again; it appears Mancini Racing has a stock replacement.
Amy suggestions are welcome.
Mark

View attachment 128101

Air is going to take the path of least resistance. So, instead of being drawn through your radiator, some air is getting pulled through the gap in the shroud into the side of your fan. It may be enough to make a difference in cooling. Notice the shroud had notches from the factory to fit the radiator tightly, so the engineers knew even those small gaps mattered. You might try some tape to seal it up and see if it makes a difference… though it may leave adhesive on the radiator once it gets hot. Could you temporarily use a C clamp to get the shroud to mate up to the radiator better? Or look at where/how the shroud is bolted to the radiator. Unbolt one side and see if it relieves pressure and takes the bend out of the shroud.

 

[michiganhotrod1]

Hello;
An update. I replaced the radiator shroud (fits better but not perfect) and the cap (good catch folks) with a 16#. Took it to the Heinz Drive cruise last Sunday and it was better behaved in traffic, gague didn,t get over 3/4. Went to check temps with my infared tester, but a dead battery foiled that.
Improvement. On to the next steps but at lest no longer a white knuckle drive.
Thanks,
Mark