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Greg A
Greg A, Master Troubleshooter
Category: Chevy
Satisfied Customers: 7946
Experience:  Working with Electronics & Cars for 25+ Years
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Resolved Question:

Submitted: 7 years ago.
Category: Chevy
Expert:  Greg A replied 7 years ago.

Hello & Welcome,


Did you feel the hoses going to the heater core?


Are they both HOT to the touch (when the engine is at normal temperature)?



Customer: replied 7 years ago.

Input hose going to heater core is warm, output hose from heater core to radiator is cold.

Expert:  Greg A replied 7 years ago.

Can you tell me what engine size you have in the vehicle? I want to see if I can find a routing diagram for the heater hoses. Having a heater hose going to the radiator does not sound quite right.



Customer: replied 7 years ago.

The engine is a 5.7 liter V8 carborated, no manufactured A/C

Expert:  Greg A replied 7 years ago.

Hi again,


I just wanted to let you know that I am having some trouble locating the diagrams for the cooling system and especially the heater hoses and where they go.


But if you have only a "warm" hose on one side of the core and a cold hose on the other side, then there is no coolant flow through the core. This could be cause by a blocked core (which you said you replaced) or maybe a blocked hose. I don't think you have a water flow valve in that particular vehicle.


The first thing I would check is the coolant level. Make sure it is absolutely FULL at the radiator neck, and if you have an overflow bottle, it should be about half full when the engine is cool.


The other thing that concerns me is the heater hose routing. Usually one hose comes from near the thermostat housing, and the other goes to near the water pump. That is why I was looking for the heat hose diagrams. If I can find them, I will let you know.


I also wanted to let you know that I will be off this system for the rest of the afternoon and most of the evening. But I will check back either later tonight or tomorrow.



I hope this helps. Please let me know what you find.


Take Care, Greg A.

Customer: replied 7 years ago.
the engine overheated and i put in some bars sealant. is it possible that the engine can not build up enough pressures to circulate the antifreeze. we did not get the head planed.
Expert:  Greg A replied 7 years ago.

Hello again,


First let me say that I am not a fan of any sealant. They are a "patch" at best, XXXXX XXXXX often cause more problems down the road, such as clogging coolant passages (which may be what you have now).


Having said that, when was the sealant put in? Was it recently, and before this heater problem was noticed?



Customer: replied 7 years ago.
I believe I put it in after the new heater core went in.
Expert:  Greg A replied 7 years ago.

Hi again,


If that is the case, I would take the hoses off the heater core and flush the core in both directions to make sure you have good flow through the core. You should be able to do this with a garden hose and it should be relatively easy to get flow through the core.


While you have the hoses off, I would also run the engine for a very short time to make sure coolant is flowing from one of the hoses going to the core. If you can catch the coolant in a clean container, you can reuse it.


I have also done a "bypass" of the heater core with a small metal coupling (pipe) and then felt the heater hoses when this is attached to verify that coolant is flowing through the hoses. You might want to do that too.


Please let me know what you find.


Take Care, Greg A.

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