waterpump question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cole · 09-22-2003, 09:38 PM

I'm going to change my water pump this weekend, (it's leaking through the weephole) so I ordered one. I was reading the instructions and it talked about internal and external bypassing. It said trucks are external and corvetts and passenger cars are internal. There is a 3/8 plug to insert into the hole for externally bypassed pumps. The problem I have is, there is no bypass hose on my water pump. Does that mean I have a car engine with internal bypassing? Or did someone change some other parts which left my engine without the ability to bypass. I am told, that if your engine cannot bypass in case of a stuck thermostat, it could cause damage. Does anyone know about this?

Thanks, Cole

jef5150 · 09-22-2003, 09:59 PM

ok, are you saying, your old pump had a heater hose going into it and now your new pump has no place to put that hose ?,,,it that what you mean?

Tx Firefighter · 09-22-2003, 11:41 PM

The outlet on the passenger side is where the heater hose goes.

The outlet on the top should be plugged with a plug.

Orion 762 · 09-22-2003, 11:55 PM

I just replaced the water pump on my '71 Cheyenne. On my engine, the original intake manifold had been replaced with an Edelbrock intake. The high-pressure side of my heater core is connected to a fitting on the intake itself, on the "passenger side" of the thermostat housing. The low-pressure side of the heater core is connected directly back to the top of the radiator.

I just plugged both "outlets" on the new water pump (not the big one going to the radiator, though).

I wasn't aware of external/internal bypassing differences. Does it matter if I did NOT tap the heater high side from the water pump??

It seems to work okay, but then my thermostat has not froze shut yet to test this out.

Please advise if I need to rehook-up these hoses to the pump.

Thanks . . . Orion 762

cole · 09-23-2003, 11:26 AM

The heater connections I understand. But should there be a bypass like the directions talk about, internal/external. I guess I'll know more when I pull the pump. I also have a highrise manifold. I just though maybe someone out there might have run into this problem.

Thanks, Cole

09-22-2003, 09:38 PM	#1
cole Registered User Join Date: Aug 2002 Location: AZ Posts: 17	waterpump question I'm going to change my water pump this weekend, (it's leaking through the weephole) so I ordered one. I was reading the instructions and it talked about internal and external bypassing. It said trucks are external and corvetts and passenger cars are internal. There is a 3/8 plug to insert into the hole for externally bypassed pumps. The problem I have is, there is no bypass hose on my water pump. Does that mean I have a car engine with internal bypassing? Or did someone change some other parts which left my engine without the ability to bypass. I am told, that if your engine cannot bypass in case of a stuck thermostat, it could cause damage. Does anyone know about this? Thanks, Cole __________________ Unemployment would have been a wonderful experience, had it not been for the lack of money.

09-22-2003, 11:41 PM	#3
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	The outlet on the passenger side is where the heater hose goes. The outlet on the top should be plugged with a plug. __________________ I'm on the Instagram- @Gearhead_Kevin

09-23-2003, 11:26 AM	#5
cole Registered User Join Date: Aug 2002 Location: AZ Posts: 17	The heater connections I understand. But should there be a bypass like the directions talk about, internal/external. I guess I'll know more when I pull the pump. I also have a highrise manifold. I just though maybe someone out there might have run into this problem. Thanks, Cole __________________ Unemployment would have been a wonderful experience, had it not been for the lack of money.

09-22-2003, 09:59 PM	#2
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	ok, are you saying, your old pump had a heater hose going into it and now your new pump has no place to put that hose ?,,,it that what you mean?

09-22-2003, 11:55 PM	#4
Orion 762 Registered User Join Date: Sep 2003 Location: Mississippi Posts: 36	I just replaced the water pump on my '71 Cheyenne. On my engine, the original intake manifold had been replaced with an Edelbrock intake. The high-pressure side of my heater core is connected to a fitting on the intake itself, on the "passenger side" of the thermostat housing. The low-pressure side of the heater core is connected directly back to the top of the radiator. I just plugged both "outlets" on the new water pump (not the big one going to the radiator, though). I wasn't aware of external/internal bypassing differences. Does it matter if I did NOT tap the heater high side from the water pump?? It seems to work okay, but then my thermostat has not froze shut yet to test this out. Please advise if I need to rehook-up these hoses to the pump. Thanks . . . Orion 762



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