68convert

A friend of mine has a 2003 ram with a 4.7l engine in it. I've replaced the thermostat and flushed the radiator twice. The first time I flushed the rad. a lot of junk came out of the petcock. The second time the antifreeze looked like it just came out of the bottle and the first thermostat looked good. But, it still overheats. It overheats when following a car or going up a hill. It can sit all day idling and never go above 200 degrees. The only things that I can think of that could be wrong is the clutch fan or a bad rad. Am I right? Also, how can you tell if a clutch fan is bad?

Thanks,

Tony

jinx10000

Could also be a blown head gasket, have air in the system, or a bad water pump.

Have you felt the hoses at top and bottom to determine if water is flowing when the truck is on?

I read somewhere on the internet that the clutch fan will roar when you first turn on the car and when the truck reaches operating temperature. I personally have not noticed that, but I don't stand in front of the truck waiting for it to happen.



I found this by searching on google.

It sounds like an air bubble is trapped inside the block. Try this, clip the end off a paper clip so you have a "U" shaped wire. Then slide it under the negative pressure relief valve of the radiator cap.

Now fill the cooling system to the top of the filler neck and place the radiator cap on tightly. Fill the coolant reserve bottle about ¾ full. Start the engine and turn the heater to full HOT.

Now just let it run and soon you will see air bubbles coming up through the coolant reserve bottle. When the engine gets to normal operating temperature shut it off. Keep an eye on the coolant in the bottle and add some to keep the level up.

That will get most of the air out of the system. You may need to repeat the procedure once or twice.

If it cools off when you are moving, then you probably have a bad cooling fan clutch.

68convert

thanks for the reply. the head gaskets are o.k. the only problem is that the pressure cap is on the overflow bottle. will it work the same way?

thanks

tony

jinx10000

I'm not sure. I've never done it.

Search google for dodge negative pressure relief valve and click the first link. It has a picture for comparison.

68convert

thanks jinx. I'll give it a try tomarrow. linc pic helped alot.

Tony

angus10

You need to flush the whole cooling system, not just the radiator! And flushing the radiator does not mean just opening the pet cock. Larger pieces will not come out of it. If you really want to flush it, remove the thermostat and put the cover back on temporarily. Remove upper hose from rad. and aim it out and over front of truck,turn the heat on high in the truck, then stick a garden hose in the rad. and turn it on. Start the motor and let the water pump do it's thing. It's messy this way but fun in a way also! lol

And BTW, make sure the fins between the rad. and condensor (if it has AC)are clean . And lastly, your prob is either that or the fan clutch.


You also say it overheats, does that mean the temp just rises some, Or is it getting way to hot?

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