CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Help --- No Heat!

I have a Dodge Ram 1500 Quad Cab 4x4 with a 4.7 V8 engine. I believe it is an SLT. For the last three years I have had no heat. I have had my thermostat changed twice, my radiator changed once, the heater core changed, the actuators changed – all four of them, and the water pump was also changed. Still no heat. I’ve had the system flushed out several times. I’ve had three separate people look at it and do the work to try and solve the problem. Before all of this I blew a head gasket, when that was fixed I lost the heat – I don’t know if the two issues can be related. Any help would be greatly appreciated.

There might be air trapped in the cooling system. Try this.

Get the engine up to operating temperature. With the engine idling, loosen the upper radiator hose clamp. Take a small flat bladded screwdriver or something simular and slip it between the radiator hose and the hose neck on the radiator. Allow the engine to idle until all the air is purged out of the cooling system. Remove the screwdriver and retighten the hose clamp. Once the engine has cooled back down check the coolant level.

Tester

"Dodge Ram 1500 Quad Cab 4x4 with a 4.7 V8 engine."
Very Good Description, So Far.

Model-Year, please ?

CSA

With the engine fully warmed up I would carefully touch each heater hose and make sure both are hot.
If they are then this could be a blend door issue.

Based on the plethora of parts that were thrown at this truck (a radiator twice?) over 3 years time it seems to me that someone is guessing and guessing badly.
You say the acuators were replaced. Something has to control those acuators…

Radiator Once, Thermostat Twice.

Some cars have a shut of valve that prevents hot coolant into the heater core when not needed. If your car does this it is a likely culpret.

It could be related to the old head gasket job.
Having all that dis-assembly done to do a head gasket meas re-assembly with new gaskets, such as intake manifold ans all the hoses and tubes. I wonder if they put a wrong gasket on and have blocked the water port for the heater tubes ?
– Follow the heater hoses to the manifold. While doing that feel if both hoses are hot when the engine is up to temp and look for a valve in one or both of those hoses.

If both hose are NOT hot, take one off at the manifold just to see if water is flowing. If not , they blocked the passage
.
If there’s a valve in the hoses, is it vacuum operated ? Did they hook up the vacuum lines incorrectly after the head gasket job ? To test a vacuum valve, take off the vacuum tube on it, then manually open the valve and put your finger over the end of the vacuum port. If the valve stays in the open position the vacuum diaphram is good and tha vacuum source is suspect.

I agree with Dog and ken above, one of the two are most likely your issue… startwith feeling your heater hoses as sugested above.:

True enough, CSA. A misread on my part. Still, this place has thrown a ton of parts at something with no success so it does make me wonder if they’re overlooking the obvious. And three years this has been going on? Wow.

Depending on the year and so on, there’s the possibiity of an electronic control glitch. Depending on the temperature, my Lincoln has certain features that prevent compressor operation, blower motor operation, heat function, and so on. Maybe this truck is similar.

The main thing is to determine if both of those heater hoses are hot or not and go from there.

IF it has the automatic temp control like a Jeep or Durango, where you set the thermostat to the desired temperature and forget it, THAT control can be messed up. If it has the type that can vary the temp right and left, it is even more likely to be the issue.

I hate to recommend a dealer, but they do have access to a different levels of knowledge that an indy shop may not. Has a dealer been involved in this fiasco?

“Before all of this I blew a head gasket, when that was fixed I lost the heat…”

I think this is the 800lb gorilla in the room.

Ken Green touched on it. I’d follow his advice, and make sure this is the problem before looking at much else, and throwing more parts at it.

Seems like everyone who’s been trying to fix this problem is avoiding it because the only true, sure way to find out is to pull the head that was fixed and see if the right gasket was used, and that it was properly installed, not blocking the water passages.

You do not have to pull the head to check flow. Start simple.

Thank you all for your replies. I will try and find someone to help me try all the things that were suggested. I don’t know my way under the hood very well. Common Sense Answer – I have a 2002. MG McAnick – The first place I brought it was the dealer and they recommended the thermostat and radiator replacement. I just had a friend look at it before I saw your suggestions and he let the car warm up and touched the sides of the radiator (black part) and said it was not hot/warm. Then he touched the hoses and say they felt warm. But he was also stumped. Does this help any?