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Discussion Starter · #1 ·
I have owned a 2003 Ram Quad Cab w. a 4.7 liter motor for about 1 full year now. It has about 48,000 miles on the odometer and is in great condition.

It has had its share of problems but the most recent one has me confounded. Here are the symptoms:

While driving at a constant speed, my trucks coolant temperature will fluctuate. If I come to a hill where I need to use more throttle, or just keep it throttled for a minute or two constantly, The temperature gauge will rise,

It usually will not completely over heat, but reach temps well over half way on the gauge. If i start to coast for a while the temperature will then go down to its normal position slightly below half-way

What i have tried:
So far I have tried flushing the cooling system, and I have replaced the thermostat with another 195 degree unit. Even with the 195 degee thermostat the gauge should pretty much stay put once the car reaches operatiing temperature.

It doesnt appear to have any air bubbles but I am not totally sure (is there any relief valve).

What else could be the problem? The water pump? it isnt loosing any coolant (im assuming it has a weep hole)

I am at a loss in regards to where to go from here, any suggestions? Ideas?
 

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bad temp sending unit???
 

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Have you bleed the system? If not follow the upper radiator hose to the hex bolt you see on the motor and try it. If thats not the problem you could possibly have a clogged radiator.
 

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Check the Radiator cap - if it does not seal well then the system will never properly pressurize which will lead to temp issues. The water-pump would be my next bet even though you are not seeing a leak while parked. last and certainly not least the head gasket... smell the radiator if it smells like exhaust you may have some engine work ahead.
 

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Discussion Starter · #5 ·
I just found the bleed valve, and attempted to bleed the system some. I dont know if there were any air bubbles but I am going to drive it tonight and see what happens. I got a feeling it isn't going to help but hey maybe i did have some air pockets in there.

The system seems to build pressure and the cap appears to be in like new condition. I say it builds pressure because I can hear a relief of pressure when I remove the cap.

I have flushed the system a few times and it doesnt seem like I have a clogged radiator but I guess that is a possibility. Any good way of checking? It drains fine and I get a constant flow through the system it seems like just by watching the cooland flow through the resovior with the cap off.
 

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The way to check if a radiator is clogged would be after driving your truck around till your engine gets to operating temperature and then with a temp gun or your hand look for hot and cold spots.
 

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Man, that's kinda got me stumped,..

I would probably check the fan clutch and make sure it has resistance when you try to skin it by hand, if it spins without any effort it needs to be replaced.

From there I would start looking at the water pump.

Good luck..
 

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Discussion Starter · #8 ·
Well just took it out after attempting to bleed the system, and Its still heating. I am starting to lean towards waterpump myself. I appears to be pumping but possibly its not flowing enough?

I am actually considering taking it to the dealership and I havent taken a vehicle back to a dealer for service ever in my life. Its just come to the point where I am so busy with work that I just dont have to time to mess with it.

The vehicle still has its powertrain warranty, (2003 with 48,000 miles) correct? If so will it cost me money to have it checked out? and if it turns out to be a waterpump or fan clutch I take it thats not considered powertrain? Or is it? I just want to know what to expect and not get taken advantage of by a dealer.
 

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What type of antifreeze did you use? Did you use a 50/50 mix? The antifreeze should be the red stuff, not the green. I put 240,000 miles on my '02 4.7 and never had a problem.
 

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This is a common problem with some 4.7s. I went thru hell and back with mine.
 

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Bad thermostat, Clogged radiator (Seems to be common on alot of the new Rams), Air in system, Bad radiator cap, Bad fan blade clutch.Water Pump. Eliminate one at a time and go from their. I'd bet it was the radiator tho.
 

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Discussion Starter · #14 ·
Are these rams supposed to have an open short piece of tubing coming out of the firewall? Its near where the two inlets for the heater core go into the firewall. It appears to be just dripping condensations I just want to make sure thats all that it is.
 

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That line is the AC drip line, it is suppose to drip when a/c in on or for a while after it has been shut off.
 

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Discussion Starter · #16 ·
ok thanks, I kinda assumed thats what it was. You think there is any reason it would be dripping when the A/C hasnt been running? I had the heat on and its about 35 40 degrees ambient temp. Thats what had me curious?
 

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Any updates on your overheating problem? I've got a 4.7 pushing 100K miles and have (KNOCK WOOD) ;) little to no problems with it so far :D .
 

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I wonder if your EGR is stuck closed. Or if you happen to be running the defroster when this happens. When you run the defrost your engine will heat up quicker & stay hot... when you turn the Defrost off the engine will cool down. This is why I think its a bad EGR or your defrost is on, either one will cause you to run hot and possibly overheat.

SPEED SAFE, AIR RAM
 

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AIR_RAM said:
I wonder if your EGR is stuck closed. Or if you happen to be running the defroster when this happens. When you run the defrost your engine will heat up quicker & stay hot... when you turn the Defrost off the engine will cool down. This is why I think its a bad EGR or your defrost is on, either one will cause you to run hot and possibly overheat.

SPEED SAFE, AIR RAM
I would think the engine would run cooler if your running the defrost or heater, since your getting rid of excess heat. The engine coolant is flowing through the heater core all the time anyway and when you turn on the heater your just moving a flapper valve to direct the air flow through it. In other words your adding radiator area for the engine.
 

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piper18 said:
I would think the engine would run cooler if your running the defrost or heater, since your getting rid of excess heat. The engine coolant is flowing through the heater core all the time anyway and when you turn on the heater your just moving a flapper valve to direct the air flow through it. In other words your adding radiator area for the engine.
I dont think you understood.

Running the "HEATER" and running the "DEFROST" are two different things.

The Heater is just that, and I use that at the track to bring down the engine temps.

DEFROST works differently. It intentionaly makes your engine run HOT by allowing hot gas run through your heads and into your intake. Running the defrost WILL cause your engine to run HOTTER... while running the heater will help cool the engine.

Next time you turn on the defrost.... make note of your AC fan kicking on.
Your AC fan does NOT come on when the heater is on... but it does come on when the defrost is on.

SPEED SAFE, AIR RAM
 
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