Flow of coolant in heater hoses - 1981
Everyone, I could use some input on the flow of coolant through the heater hoses. Sorry for this long post.
Briefly, about a year ago I purchased a 2,500 mile 1981 Corvette. At the time of purchase, the prior owner disconnected the heater hoses from the heater core and just clamped the hoses to a pipe so coolant bypassed the heater core. Given the low mileage, I thought for sure the heater core was fine.
Sadly, upon connecting the hoses to the heater core, the dreaded drip of coolant on the passenger side floor mat occurred. Thus, I was faced with removing the heater core to have it rebuilt. I removed the heater core and had a local, well respected, radiator shop replace the core. The shop agreed to use the original side tanks so that I could retain the correct inlet/outlet pipes and save the date code (this same radiator shop repaired the heater core on my '82 which works perfectly).
I reinstalled the repaired heater core (without running coolant through it first to make sure no clogs, my first mistake). Everything was reassembled but no heat. Clearly coolant is not passing through the heater core.
So, I need to determine where is the coolant not flowing. Yes, I know there is a coolant shut off value that is actuated when you move the "cold-hot" lever all the way to cold. This value can get stuck closed. I will test that. But, before I do so, I thought I would pass coolant through the heater core to see if it flows through it. I plan to flow coolant through the core in both directions so that if there is an obstruction, maybe the reverse flow will help dislodge the obstruction.
There are two heater hoses that connect to the heater core, one hose has a 3/4" inside diameter hose and the other has a 5/8" inside diameter hose. The 3/4" ID hose comes from the water pump through the shut off value and then to the core. I will call this the "outbound" hose. The 5/8" hose passes from the engine intake manifold directly to the heater core. I will call this the "return" hose. Does the coolant flow from the water pump through the shut off valve to the core, then out of the core directly to the intake manifold (I think this is the direction of flow) or does it flow in the reverse direction?
Other than: (a) passing coolant through the core in both directions to see if there is any obstruction (I will disconnect the heater hoses, install outside hoses connected to a hand pump and a pail of coolant so that I can independently pump coolant through the core), (b) flowing coolant through the "outbound" hose that has the shut off valve to make sure the valve is not stuck closed and there is otherwise no obstruction in the hose itself, and (c) passing coolant through the "return" hose to make sure there is no obstruction in that hose, is there any other test I should perform? Is there anything else I am missing? Is there a better way to go about this? I would really hate to have to take the core out of the car for further repair so I want to eliminate all possible problems before I have to tear apart the dash again to take out the core.
I just want everything to work in this low mileage beautiful Corvette. This is the last problem to fix. I appreciate any comments you may have.
Harris
Briefly, about a year ago I purchased a 2,500 mile 1981 Corvette. At the time of purchase, the prior owner disconnected the heater hoses from the heater core and just clamped the hoses to a pipe so coolant bypassed the heater core. Given the low mileage, I thought for sure the heater core was fine.
Sadly, upon connecting the hoses to the heater core, the dreaded drip of coolant on the passenger side floor mat occurred. Thus, I was faced with removing the heater core to have it rebuilt. I removed the heater core and had a local, well respected, radiator shop replace the core. The shop agreed to use the original side tanks so that I could retain the correct inlet/outlet pipes and save the date code (this same radiator shop repaired the heater core on my '82 which works perfectly).
I reinstalled the repaired heater core (without running coolant through it first to make sure no clogs, my first mistake). Everything was reassembled but no heat. Clearly coolant is not passing through the heater core.
So, I need to determine where is the coolant not flowing. Yes, I know there is a coolant shut off value that is actuated when you move the "cold-hot" lever all the way to cold. This value can get stuck closed. I will test that. But, before I do so, I thought I would pass coolant through the heater core to see if it flows through it. I plan to flow coolant through the core in both directions so that if there is an obstruction, maybe the reverse flow will help dislodge the obstruction.
There are two heater hoses that connect to the heater core, one hose has a 3/4" inside diameter hose and the other has a 5/8" inside diameter hose. The 3/4" ID hose comes from the water pump through the shut off value and then to the core. I will call this the "outbound" hose. The 5/8" hose passes from the engine intake manifold directly to the heater core. I will call this the "return" hose. Does the coolant flow from the water pump through the shut off valve to the core, then out of the core directly to the intake manifold (I think this is the direction of flow) or does it flow in the reverse direction?
Other than: (a) passing coolant through the core in both directions to see if there is any obstruction (I will disconnect the heater hoses, install outside hoses connected to a hand pump and a pail of coolant so that I can independently pump coolant through the core), (b) flowing coolant through the "outbound" hose that has the shut off valve to make sure the valve is not stuck closed and there is otherwise no obstruction in the hose itself, and (c) passing coolant through the "return" hose to make sure there is no obstruction in that hose, is there any other test I should perform? Is there anything else I am missing? Is there a better way to go about this? I would really hate to have to take the core out of the car for further repair so I want to eliminate all possible problems before I have to tear apart the dash again to take out the core.
I just want everything to work in this low mileage beautiful Corvette. This is the last problem to fix. I appreciate any comments you may have.
Harris
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