Looking for some pointers.....just rebuilt my 455, installed, broke in the cam....all seems to be really good. Except that is, for the heat. My heater core is only 2 years old. Heat PUMPED hot prior to pulling the motor. I reinstalled the heater core hoses just as before, connected the vac hose to the valve etc. As the motor run fully warmed up, if I squeeze either of the heater core hoses, they are cool, no fluid flowing. Heat blows ice cold. Would that valve thing stop the flow completely if not being opened?
Ok....update....so I disconnected the little vacuum hose that comes from firewall...to that valve that is connected to heater hose....and connected my vac hand pump. Started the car.....and almost immediate hot coolant began flowing through heater core....super hot heat. SO.....that hose that goes into firewall....where does it get it's vacuum from? I assume it connects somewhere behind the dash. Can I just eliminate the valve? Or that will always have hot coolant flowing?
You can bypass or eliminate the valve. Doing so will allow heated air into the heater box (ducting), and will interfere with AC by diluting with heated air. (Due to all time flow of heated coolant though the heater core) But you can bypass the water valve if you want to drive and while you troubleshoot and ensure all the components are working. Just make sure all the vacuum lines are connected or plugged so you don't have vacuum leak to the engine.
Thank you very much for the input. So let me understand....that canister thing mounted on the firewall, is connected to the carb. I assume that take vacuum and dispersed into the dash or heating controls? That make sense? Could the canister be bad? As you are right....I did not consider a vacuum leaks that affects the motor
The vacuum opens or closes the valve to allow coolant to flow through the heater core for heat, and stop flow when AC is on. Some of the inner doors and flaps on some models are also controlled by vacuum. Yours may well both control the flow of air in the plenum (box/ducting) as well as the valve. I do not have enough info (or manuals) on the various models but sure someone has the 1971 Skylark/Special/GS and can help. If you do not have the Buick Service manual, it is a great investment, and you can get them for about $30 on eBay or "used books" sellers. If you want, I can do some digging for manuals.
The valve should receive vacuum to close flow when the AC is on. It should only have vacuum when the heat selector is is in one of the AC positions. If it has constant vacuum, your heat control has failed. The canister on the firewall is a vacuum tank for the heat controls. Without it the controls would lose vacuum everytime you mash the pedal. It should be connected to manifold vacuum
Ok....well....I should probably delete this post all together...basically due to embarrassment....but perhaps my embarrassment will help the next. You triggered me with Vacuum leak. Stupid...Stupid. The hose from canister to back of carb had slipped off. NOT good...major vac leak. Reattached....heat works as it should. No need to dig in manuals.....but thank you so very much! Sometimes we over look the obvious
So the valve needs vacuum to be open and allow coolant flow? I thought it was opposite of that. Good to know.
No need to be embarrassed... Everybody here has overlooked something simple more than once. Glad you solved your problem.
You probably have the wrong valve. There are two different valves that look the same and they work the opposite of each other. You might have one for a C body. Easy to check, turn it to high heat, start you car and check the hose. see if you have vacuum. Now turn the ac to high and check the hose again, vacuum or not??? It should be when the temperature lever is fully to the left, the water valve has no vacuum. If you move the temperature lever part of the way or all the way to the right, vacuum will be applied and the water valve will open and flow coolant to the heater core. Another thing you have the inlet on the water valve swapped. You might try switching it the correct way and see if that helps. Let is know what you find.
Ha!!! See....u guys know your stuff....I am impressed....it was originally an a/c skylark with the ole 350. I yanked it all, installed one of those American graffiti firewall covers several years ago. Good catch! It's all good now.
I thought the heater hose connected to front of motor and not the back. 455 different? Wouldn't it be better to be at the front of the motor after the water goes thru the heads?
Doesn't matter, the water comes out of the head. The water pump pumps coolant into the block and it comes out of the heads. Stock intakes block the rear head coolant outlets. The Edelbrock intake has an additional threaded hole on the passenger side rear. You can use that hole for the heater, or temperature sender.
