As far as the bypass valves, I've seen some really neat arrangements! Bubba uses a regular gate valve that you'd see on a garden hose!

daveb12 said: As far as the bypass valves, I've seen some really neat arrangements! Bubba uses a regular gate valve that you'd see on a garden hose!

yeah but dont use bubba's method... get a real valve it will have an h design.... so that you have a complete "circuit" whether the valve is open or closed..

it you have one of these vavles its a good idea to open it up every couple of weeks to allow the water in the core to get recirculated leaving it closed tends to degrade the corrosion resistance of the anti-freeze.

I bought a full port ball valve that already had 5/8" hose barb connections from Home Depot (about 5 bucks) cut one heater hose (the 5/8" one) and installed the valve with hose clamps, took care of most of my cabin heat, and I can open the valve whenever I need heat. Most people wouldn't even notice the valve hiding under the A/C compressor! There is a damper in the ductwork that is supposed to stop air from blowing through the heater core, but leakage from old seals (that were not all that great even when new) is probably most of the problem.

I have a 73 -454ci, with that same problem. The by-pass value your talking about, does it get connected between the 2 heater hoses on the passenger side of the engine compartment?

the shutoff method is one way of doing this..

the bypass is better..

you cut your heater hoses near the firewall at any convenient spot then install the bypass valve..

it basically splices both hoses and allows you to loop the flow though the valve or let it pass through.

if youre still confused.. goto the parts store and buy one... once you take a look at it you will no longer be confused.

|UPDATED|6/29/2004 11:00:52 AM (AZT)|/UPDATED|

cthulhu said: the shutoff method is one way of doing this.. a shut off adds resistance load to the water pump. a bypass does not.

Sorry, but I must disagree. If you have a pump running and have am ammeter connected you can observe the amp draw go down while throttling off the discharge of the pump. This is how the flow of pumps is matched to system requirements in commercial buildings for hot or cold water applications.

I can also say I have seen many cars with control valves that shut off only one line.

Edit: adding resistive load would only be true if the pump was a positive displacement type of pump, like a rotary vane or diaphram. Centrifugal pumps used in cars are not positive displacement.

|UPDATED|6/29/2004 3:52:19 AM (AZT)|/UPDATED|

Big Fish said: Edit: adding resistive load would only be true if the pump was a positive displacement type of pump, like a rotary vane or diaphram. Centrifugal pumps used in cars are not positive displacement.

I stand corrected.

Big Fish has it right. The type of pump makes a big difference.

The only caution. This does not apply to a C3 or any small block Chevy. Some cars require the flow through the heater core to create the proper flow through the cylinder head. Stopping the flow will cause the cylinder head to overheat. Example is the 2.2L Mopar engine. Omni, Horizon, K cars Aries, Reliant, Daytona, MiniVan, etc.

But why the heck am I talking about them?

Anyone have a picture what the bypass valve looks like?

kstyer said: Big Fish has it right. The type of pump makes a big difference. The only caution. This does not apply to a C3 or any small block Chevy. Some cars require the flow through the heater core to create the proper flow through the cylinder head. Stopping the flow will cause the cylinder head to overheat. Example is the 2.2L Mopar engine. Omni, Horizon, K cars Aries, Reliant, Daytona, MiniVan, etc. But why the heck am I talking about them?

is there a case you know of where using a shutoff is better than a bypass??

ie.. ive always seen cars factory equipped with a bypass. I havent seen one equipped with a shutoff.. Ive seen plenty where the shutoff was added after the fact, often with lawn and garden type valves.

I saw a mopar advisory notice on this once, they said not to use a shut off, and to replace any defective bypass valves with part number ????(bypass part number long since forgotten). They were talking about larger and older vehicles.. is this a mopar specific issue.

Ive also seen an advisory about shut offs with elctric night time water heaters, but i cant imagine why your valve would be closed during the cold season.

now im curious

|UPDATED|6/29/2004 6:14:34 PM (AZT)|/UPDATED|