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Leo, Auto Service Technician
Category: Dodge
Satisfied Customers: 770
Experience:  2005 Dodge ASE master technician of the year
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dakota: with a 4.7 that over heats..anti-freeze..radiator..overflow

Customer Question

i have a 02 dakota with a 4.7 that over heats after driving several hours. after driving at highway speed to sitting at stop lights, the truck will start running hot until i start driving. i found that the anti-freeze in the radiator will be will be empted into the overflow container. also i can here what sounds like the anti-freeze boiling in the engine. when the engine cools and the radiator cap is removed a large air pocket is found. the anti-freeze from the overflow tank is empted back into the radiator and it will happen again every few days. i change the thermistat, water pump, upper & lower hoses, heater hoses, fan clutch and flushed the radiator. could the problem be a blown head gasket or a cracked head.                                          ;                                         &nb sp;     thanks for your help
Submitted: 9 years ago.
Category: Dodge
Expert:  Leo replied 9 years ago.


It's only overheating on you when your sitting at lights or idle? Or does it also overheat running down the road?


Customer: replied 9 years ago.
Reply to Leo's Post: it only over heats when the truck is at a stand still. i purdged the air out of the cooling system today for the first time. lets see if that works.
Expert:  Leo replied 9 years ago.


The fact that it only overheats when your not moving really indicates a cooling fan issue.

Your truck is equipped with two cooling fans, 1 mounted to and driven by the waterpump. The second fan is electric, and mounted on the back of the radiator (if you peek in with a light you can see it). The electric fan is VERY loud. Loud enough to mostly drown out the engine noise at idle, and can easily be heard with the hood closed from several feet away.

I strongly suspect your having an issue with the electric fan. Diagnosis can be tricky without a scan tool to actuate the fan and test out the circuits.

Another common problem with Dakotas is the radiator cap.. The seal goes bad and allows coolant to be pushed out when the engine warms, but not drawn back in when it cools down.. This leads to an overfull jug (the overflow jug) and a low coolant level in the radiator. I would have the cap tested.

The 4.7 motor does not tolerate overheating very well, it doesn't have to get hot to many times before you wind up with warped cylinder heads, be very carefull not to let it overheat if possible.

I suggest having the electric cooling fan operation checked out as soon as you can, to prevent more serious engine damage. You should be OK at this point, as it doesn't overheat on you going down the road. While it's in have them pressure test that radiator cap.

I hope this helps, if you have any questions or need clarification don't hesitate to ask!


Leo and 5 other Dodge Specialists are ready to help you
Customer: replied 9 years ago.
hi leo,
the purdging of the radiator didnt work. the anti-freeze is still pushed into the overflow tank. when the bleeder hex head nut is loosend at the water neck and the engine is started from cold, air bubbles will not stop escaping from the bleeder hex nut after it is refilled.
i replaced the fan clutch on the water pump mounted fan last week. the electric fan will turn on when the temp is a little over the half way mark. i also changred the radiator cap several times 18,20 and 21 psi caps.

the truck has 170,000 miles on it. at 70,000 miles the upper (in line filler cap) radiator hose blow cousing the engine to over heat. could the over heating two years ago be the problem.

Expert:  Leo replied 9 years ago.

H Randy,

The fact that it only overheats at idle and not going down the road is the part that's throwing me off.. That typically is an issue with a coolilng fan, or poor coolant flow through the radiator.

The bubbles are also bothering me.

I think the next best step is to swing by the parts stores and get one of the kits for checking for combustion gasses in the cooling system. They generally fit over the cap and have a little liquid in them that changes color when exposed to exhaust. If it changes color on you then it's a headgasket or head issue.

When it's up to temp (but not overheating) and the fan comes on does it feel like it's pulling hot air through the radiator or is it just luke warm?


Customer: replied 9 years ago.
Hi Leo,
I had several auto technision look at the engine. it was found that the back cylinders on the drivers side were found to anti-freeze contamination. also this week a milky off white foam is forming on bottom side of the oil filler cap. it must be a bad head gasket or crack head. the owner of a auto repair shop had several option;
1)replace the head gasket if the head is still in good shape.
2) if the head is bad also replace the head, but he also said to keep in mind that the lower end has 170,000 miles on it.
3)replace the engine with a junkyard engine with less miles.
4)trade in the truck for another on and have a truck payment.

im meeting with him next week to determine what im going to do.

thanks for your help leo,
randy from mass.
Expert:  Leo replied 9 years ago.

Hi Randy,

Thanks for accepting my answer and the bonus, I appreciate it. Sounds like they have found the source of the issue. He gave you options, sounds like a good shop to deal with.


Customer: replied 9 years ago.
hi leo,
Gurneys is the shop, its been in operation for 40 years in the same location. some family member have used the past for repairs. i had a 383 chevy stroker moter built by a speed shop (R.A.D. Auto Machine, Inc.) several years ago. RAD suggested that Gurneys would be the shop to go to for the repair of the 4.7.

ill keep you informed,
Customer: replied 6 years ago.

Hi Leo,

How is everything going with you, a lot of snow here. Im just replying to your e-mail about the update on my 4.7 dodge engine problem from January of 2008. Every 100 miles I would need to let the engine cool, siphon the anti-freeze from the overflow container and add it back into the radiator. This went on until June of 2010. The truck now had 236,000 miles on it. At that point I had a remanufactures engine installed along with a new cat system. The truck has 254,000 on and it runs great. Thank you for your help.