Engine overheating, coolant not returning to radiator

Maintenance/Repairs
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1

Hi all,
I have a 2009 Dodge Ram 1500 with the 4.7L engine in it. It has 190,000 miles on it. It has several problems related to the cooling system…

  1. Coolant just randomly disappears. It used to be that the engine would try to overheat but wouldn’t reach H. Took it to the mechanic since it was misfiring and overheating, they replaced a couple plugs and coils and added coolant since it was low. 15 minutes after I took it home from the shop, I started it up and it started running bad again, so I took it back, and they said that since the engine was running bad and the coolant was already low again that I have a head gasket leak. Consequently, I put blue devil in it as per their recommendation and it seems to have slowed down the leak, and the engine usually runs fine now but still tries to overheat at times.

  2. The coolant overflow/reservoir was very low on coolant. Keep in mind I did this when the engine was cold. So I topped it off, and I checked the level when the engine was running and it was still full but the radiator was substantially low. I know that the cooling system is building plenty of pressure because when I open the cap when the engine is warm (not hot), it makes that big whoosh sound. It seems to be that no matter what the coolant level in the overflow does not change. Maybe a clogged hose?
    I have topped off the coolant in the radiator and let it bleed for 25-30 minutes and the level in the radiator is fine for a little while and then the coolant mysteriously disappears. The cap and engine bay is always dry so I don’t think it is letting coolant escape.

  3. It has a single zone climate control. When I turn on the heat, the heat only works on the drivers side for about 2 seconds and then immediately goes cold; however, the heat on the passenger side is just fine.

I’m not too worried about it since I have found something else to make my daily driver.

2

Remove the radiator cap while the engine is cold.

Start the engine, and as it idles watch if bubbles form in the coolant.

If they do, that’s a blown head gasket.

Tester

2 Likes
3

A blown head gasket would also explain the radiator not taking coolant. Sometimes exhaust is forced into the coolant passages, depending on where the head gasket is leaking. Exhaust getting forced in, you’ll never keep the radiator full.

4

Yeah, +1 for a blown head gasket. Have the coolant tested for combustion gases, and/or use Tester’s method above.

5

Are you certain there are no external cooling system leaks? Like at the water pump seal? If there are such leaks, that will create an air pocket in the cooling system and cause overheating and the weird passenger compartment heater issues. Ask you shop to carefully inspect from under the car for any signs of coolant leaks. In some case you can have a coolant leak that evaporates before much of it ever hits the ground. Suggest to also put a clean piece of cardboard under the car when you park it for an overnight rest, after some extensive driving, then you’ll be able to see signs an external leak the next day.

Anothr possibility, the radiator pressure cap (or wherever that’s located) could be the problem. Might want to take a gamble on replacing it, esp if it is original to the vehicle.

Your symptoms do sound like a head gasket leak, but some further testing seems in order.