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Coolant through the heater core

skyman51

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Other than correctness, does it really matter which way the coolant flows through the heater core? In other words the hoses are incorrectly installed as far as the input and output.
 
Not really, but depending on year (where the heater valve is located) it would seem to be best for the valve to shut off the flow before it gets to the heater core in case of leaks.
 
I'd have to say it's hooked up a certain way for a certain reason.
I'd also say the water pump will push water either way though the heater core.
What year car and motor?
 
In a heating coil it is general practice to pipe the heater with flow in the bottom of the coil and out the top of the coil. Not hard to change hoses.
 
In a heating coil it is general practice to pipe the heater with flow in the bottom of the coil and out the top of the coil. Not hard to change hoses.
I agree with this, helps with removing air.
 
The car is my 67 Hemi. The heater core inlet and output are horizontal and not vertical. The hoses are installed backwards. A radiator guy and a master mechanic said it really won't make any difference which way the water flows through the core. It has nothing to do with the engine cooling. The heater works perfectly and the car runs at the correct temp. I don't want to risk damaging the heater core or paint on the block by switching the hoses.
 
It's your call. Not hard to switch if you wanted to. Won't hurt anything if you don't. Just curious though, my 70 has different size hoses and connections. Are the hoses on a 67 the same size?
 
It's your call. Not hard to switch if you wanted to. Won't hurt anything if you don't. Just curious though, my 70 has different size hoses and connections. Are the hoses on a 67 the same size?
Yes the hoses are the same size on a 67. GM always made them two sizes. I don't know why they are the same on the 67 GTX. T
he nipples on the heater core are the same too.
 
Water flow direction doesn't matter so much with a car that doesn't have ac, but it does matter if it does because the shut off valve needs to stop the hot water so the ac coil will remain cold as the air goes past it. The valve will not completely shut off all the water, as the ac coil could freeze up, so a bit of water flow still goes through for that reason.
 
Water flow direction doesn't matter so much with a car that doesn't have ac, but it does matter if it does because the shut off valve needs to stop the hot water so the ac coil will remain cold as the air goes past it. The valve will not completely shut off all the water, as the ac coil could freeze up, so a bit of water flow still goes through for that reason.
No shut off valve and no A/C. I am going to leave it alone.
 
skyman51 I'm not being a Smart A., just curious, would these hooked up wrong hoses be on your 67 Hemi GTX 1st. place Concourse de Elegance winner?
If the hoses have not been installed for to long of a time, they could slip off with out much trouble. If in place for a long time period then you may have to cut the hoses.
So I see your choice now is to leave them as is.
 
A radiator guy and a master mechanic said it really won't make any difference which way the water flows through the core. It has nothing to do with the engine cooling.

I beg to differ.

The first thing you do when driving and the engine temperature increases too much is to turn your heater to FULL Hot. That brings the temperature down enough to get to a place of inspection or repair.
As far as the correct way around for the hoses, I don't know about Hemi cars, but all others have two different sizes nipples from what I've seen. So putting them the wrong way around means that someone has used too small a hose on one nipple, and too big a hose on the other. One will likely fall off, and the other could possibly split open.

Might be a good time to get a new Master Mechanic. :rolleyes:
 
I beg to differ.

The first thing you do when driving and the engine temperature increases too much is to turn your heater to FULL Hot. That brings the temperature down enough to get to a place of inspection or repair.
As far as the correct way around for the hoses, I don't know about Hemi cars, but all others have two different sizes nipples from what I've seen. So putting them the wrong way around means that someone has used too small a hose on one nipple, and too big a hose on the other. One will likely fall off, and the other could possibly split open.

Might be a good time to get a new Master Mechanic. :rolleyes:
His mechanic is correct. The heater core will work the same regardless of direction of flow. When he says it has nothing to do with engine cooling I'm sure he's talking about design. You can still run your heater to aid in cooling the engine, it will work the same. Also he stated earlier that his hose connections are the same size.
 
I was just pressure washing my engine bay and shot water in the two outlets from the core. It would only go in one and not the other so I would say it does matter.
 
dla4567, not sure why you are disagreeing with everyone, by chance did you hit the wrong button?
 
Non AC, water will flow either way.

Edit: I should add something here at this time, please correct me if I'm wrong.
The B, RB and 426 Hemi water pump are the same item, and the water flows only one way though the water pump and also water flows out the rearward most stub/nipple (outlet) and in the forward most stub/nipple (inlet).
Water flows in the smaller heater core stub (inlet) and out the larger heater core stub (outlet).
Now I do not know at this time if the heater core stub diameters are the same for the 426 Hemi compared to the B&RB motors.


I'd say only one way is correct.


heater core 1970 x3.jpg
 
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