Cooling Issues with My 72 Challenger

[73restomod]

Could be a clogged radiator, had a similar problem with a 340 once. The radiator was used, but worked great on a previous 318. However it didn't flow enough on hot days when idling much, or with stop and go traffic; to keep the extra juice from the 340 in check. I took it to a radiator shop, had it cleaned, flushed, and flow checked for 49 bucks and some change. Afterwords the motor never went above 180, not even when I smoked a Honda Civic repeatedly on a 35 mile ride home.

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[jdavis2169]

Just wanted to see if problem is fixed. Another possibility is does the car have a fuel return line on it. From what i heard from quite a few people is without 1 there cars ran warm in traffic. Also any chance the fan pully might be the wrong size? It might not be spinning the fan fast enough. Please correct me if i am wrong guys.

[ghjedi]

Another thing you can do is start the car up with the radiator cap off. Check the flow across the radiator with the engine running and warmed up. There should be a good bit of turbidity/flow at idle. If the flow appears reduced or restricted, it may be a clogged radiator and/or a worn water pump. I've seen a lot of people that buy an older car and the coolant is 25 years old and never been changed & they wonder why the car overheats!  Good luck with yours! 


                                                                              Matt B.

This flow test is definitely on my weekend list to do.  I've replaced the thermostate twice now and the fluid has been changed 3 times since I bought the car 2 years ago.  I've also tried 'water wetter' with some moderate success.  The radiator appears fairly new (i.e. less than 5 years old), but I can't say for certain how old it is.  When I've visually checked the inside, I can see that it is very clean inside without any obvious signs of rust or corrosion.  But, I know that what one sees with the cap off is only part of the story.

What makes this hard to diagnose is that the car doesn't leak a drop of coolant anywhere and I can take it out several times before the temp gives me trouble.  The pattern I've noticed is overheating while driving around town with frequent stopping/starting-- even in moderately warm days (70s to low 80s F).

I'll update this post again after I've tested a few more things this weekend.  Thanks again for all the helpful suggestions.  I'm eagerly awaiting the day when I don't have to worry about making it home or not from the local grocery store.

[ghjedi]

Another thing you can do is start the car up with the radiator cap off. Check the flow across the radiator with the engine running and warmed up. There should be a good bit of turbidity/flow at idle. If the flow appears reduced or restricted, it may be a clogged radiator and/or a worn water pump. I've seen a lot of people that buy an older car and the coolant is 25 years old and never been changed & they wonder why the car overheats!  Good luck with yours! 


                                                                              Matt B.

Ok, here is an update on my issue.   I checked the flow of coolant after warming up the car with the radiator cap off.  After warm up, there was flow, but not very fast or turbulent.  The car didn't overheat in my driveway and the temp across mulitple parts of the block/value covers stayed in a good range near 170F.  I noticed that my passenger side of the radiator was 10F-15F hotter than the driver side, but I'm thinking this has more to do with the hose inlet on the passenger side than anything else.

Given that I have a new water pump, I'm leaning towards a restricted radiator as the source of my problem.  It's also possible the previous owner did not upgrade the rad after installing the big block engine.  Mine measures 27.5 inches wide by 21.5 inches long and 2.25 inches wide.  I stil lneed to check the number of rows inside after the temp cools down.

What do you guys think?

[moparmaniac59]

Sounds like you've got the big radiator (26"). It also sounds like your radiator may indeed be restricted. I'd pull it out & take it to a good radiator shop and have it flushed. They can do a much better job than the do-it-yourself flush. Another option is to leave the radiator installed & have the whole system flushed. It should take care of the flow restriction. You can always buy an aftermarket aluminum radiator for a few hundred bucks & probably not much more that the cost of a system flush. They are making quite nice radiators now for a very good price & some have much more flow than the factory radiators. Unless of course you want to pay the big bucks and get a "BeCool" radiator. Good, but VERY expensive! 

                                                                          Matt B.

[ghjedi]

Sounds like you've got the big radiator (26"). It also sounds like your radiator may indeed be restricted. I'd pull it out & take it to a good radiator shop and have it flushed. They can do a much better job than the do-it-yourself flush. Another option is to leave the radiator installed & have the whole system flushed. It should take care of the flow restriction. You can always buy an aftermarket aluminum radiator for a few hundred bucks & probably not much more that the cost of a system flush. They are making quite nice radiators now for a very good price & some have much more flow than the factory radiators. Unless of course you want to pay the big bucks and get a "BeCool" radiator. Good, but VERY expensive! 

                                                                          Matt B.

Thanks Matt.  Unfortunately, there aren't any local radiator shops, so I will try the system flush. 

If I do need to purchase new, do you know if there are any black aluminum radiators?

[brads70]

If I do need to purchase new, do you know if there are any black aluminum radiators?

Any aluminum rad can be black, try BBQ spray paint. Works great!

[ghjedi]

Any aluminum rad can be black, try BBQ spray paint. Works great!

Thanks Brad.  I wouldn't have thought of BBQ spray!