Radiator cap = overheating?

[AKcharger]

My car does good on trips and around town for temp but in extended stop and go traffic like 30+ minutes it gets very hot, like pull to the side type stuff. Could a low  7psi cap cause this problem? I've since swapped it with a 16psi cap..just wondering if problem could have been caused by the cap.

Thanks AK

[Rocky]

for every 1lb of pressure, you raise the boiling point 2+ farenheit.  I would not run a cap under 15lbs in any car that I drive just for that simple fact.  If your car boils over at 220F, that is your problem, however there are are other ways to help the situation.  If you don't have a fan shroud, then I would suggest that as the next step after replacing your radiator cap.

[Chryco Psycho]

I agree it could have been a problem for sure

[AKcharger]

Gotcha

I don't have a fan shroud but the reason is I have a non-standard radiator...let me check part # and see if I can find a match for it

[cudaken]

 Are you boling over our getting hot? When do you get hot, around town and cool off at 60 MPH. Or is it the other way around? Cool around town and hot on the high way?

Details. Bad cap will cause it to boil over quicker. Well what little I know.

                          Cuda Ken

[AKcharger]

Cools off at speed, just sitting drives temp into "hot" zone...forget actual temp

[cudaken]

 Sound's like the fan is not moving the air flow you need. Check your fan clutch, if it spin's freely then more than likely a new one is in order. That is if you have a fan clutch. Has this just started and if so had you changed anything befre it started happing?

                                  Cuda Ken

[AKcharger]

I'm using a 'factory flex fan" I cannibalized off the 400 magnum from my wife's '72 ( gave her the old steel fan...don't tell her!) So fan works good and even with the old steel one it did fine. In Alaska there is no such thing as traffic jams...not the case here in VA! It would always get hot in traffic but we would move along enough where it wasn't a problem.

I really noticed it at Carlisle on the 5 mile 45min drive from the Holiday Inn to the show. It did OK for about  ½ an hour then got hot and puked as I drove though the gate…very embarrassing…but that was the 7 psi cap.

[cudaken]

 AK, I do not know the newer Mopars (after 71) that well. Factory Flex Fan? Never heard of one. I would try the old steel fan again. If the Factory one is like the cheap ones I used they will ware out and blade's will lose some of the bend. That would mean they pull less air than when new. A bad cap or low PSI cap would cause a boil over, but it just controls the boil over temp.

I dont claim to know every thing but due know what has happen to me. I have had a lot of over heating problem's in 400,000 miles plus in old Mopar's and 33 years. I have never had a over heating problem fixed by a cap. New exhaust yes, cap No.

              Cuda Ken

[8WHEELER]

Factory flex fan no, maybe he means clutch fan?? they can go bad seen many.

Dan

[cudaken]

 8 wheeler, I think you may be right on the wrong term being used. Bet it is a clutch fan and not a flex fan.


                                    Cuda Ken

[Ghoste]

Mopar did offer a flex fan on some cars.  I have one on mine that I robbed from a Cordoba.

[AKcharger]

Nope it's a flex fan alright. Steel fan with aluminum blades. and has Pentastar on it. If it's a fake it's a good one. If anyone is real curious I can snap a picture?

[Ghoste]

Mine tends to get pretty warm at slow vehicle speeds too so maybe we both have crappy worn out flex fans?

[AKcharger]

  perhaps...but it's quieter then the steel one

[Ghoste]

I don't know.  My car is loud enough that I don't worry too much about fan noise.

[cudaken]

 Pen star or not I would try a steel fan. Like I said, I never seen one but that does not mean they where not made.

More than likely the aluminum has fatgied and lost there cruve some what. Nothing was ment to last for ever. I had a after market one on my Road Runner for around 50,000 miles. One day it threw part of a blade off. Just lucky it did not hurt anything.

                               Cuda Ken

[AKcharger]

Copy Ken...I've heard bad storys about flex fans that's why I never trusted them till I saw the factory one. I might just change over to a clutch fan

[Ghoste]

Flex fans definitely have a bad rep and I don't know if it's oem and aftermarket or just aftermarket ones but I suspect both to a degree (Iremember Ford having problems with oem ones).
I check mine periodically but I would still rather have the clutch in there.