Im at a roadblock here. I can't figure out what the deal is with the heater. I put a new heater core in, and found out some of the controls for it are broken. Thats ok since I can just push the flaps by hand to keep the heater on all the time if I want. The problem is that it doesnt seem like im getting enough coolant into the heater core.

Ok so on the water pump there are two outlets. I have the hose connected to the outlet on the right of the water pump, connected to the left side of the heater core. Is this correct? So basically the hoses cross eachother on the way from the water pump to the heater core. Are the two outlets on the water pump supposed to be right next to eachother as well? I just don't get why it seems to be sucking the coolant up and bringing it back out in pretty much the same spot.

Now I messed with the flap under the dash right where the heater core sticks out the firewall and I had it to where coolant came out the tube on the right under the hood. The problem is that the hose going into the heater core is hot, while the one going out of it doesnt seem to be nearly as warm as the other one. I have the flap under the dash flipped all the way so it should be letting through as much as possible. Its like there isnt enough pressure pushing the coolant through. Does anyone have any suggestions? Im at a loss here. Thanks.

The heater core is supplied off the fitting screwed into the top front of the cylinder head. The coolant is routed out of the heater core and to the rightmost nipple on the water pump neck. It doesn't make much of a difference which hose goes to which heater core pipe. The fact that one heater hose is hot and the other is merely warm can mean two things: Either the heater core is doing its job, wringing heat out of the coolant, but the airflow within the airbox is wrong so you're not getting the hot air into the passenger compartment, or the fluid path is blocked. You've obviously got no problem on the supply side of things, since one of the hoses is getting hot. Remove the other hose (the one connected to the water pump, remove it at the water pump and temporarily cap the nipple) and see if you get a solid gush of coolant when you start the engine. If not, find and fix the blockage. If so, go back inside the car and focus on airflow.

Also remember that if there's a significant cold air leak that lets air into the car without its first flowing through the heater core, you won't get much effective heat. Also check the cowl isn't plugged up with leaves and junk.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Remember Also, "That Flap" Does Not control The Flow Of Coolant Through The Heater Core. It Will Only Damn Up The Airflow From The Fan Or Divert It Between heat And Defrost Ducts...
The Fluid Comes No Matter What.











I Think?

Let's review the coolent flow paths.
Hot water fron the cylinder head is routed to the heater core.
After heat exchange, cooler fluid is sucked back into the water pump, to be sent thru the engine again.

From your discription, it sounds like you do not have the "pressure - suction" relationship needed to get good circulation thru the core.
DD

Depending upon how original your setup is, you might have a water control valve stuck in the closed position. On my son's Dart Sport, one hose (I don't remember which) has a vacuum-actuated water valve installed in-line. The dash heater control switch operates on a vacuum and draws open the water control valve (mounted on the passenger side inner fender) to allow the flow of hot coolant on its way through the heater core. See if you have that valve and determine if it is working properly. I got a replacement at NAPA that did not have the original-style attached mounting bracket, so I made my own.

Jerry

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

The only A-bodies with heater control valves are '65-'76 with factory A/C.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Since I just had it rebuilt and out of the shop the other day, I took it back in and told them to put another water pump on it. It just wasnt getting much coolant pumped through the heater hoses. I also started to notice that even immediately after driving, there was no pressure released when I pulled the flap on the radiator cap. So hopefully I'll have it out today or tomorrow and I can get back to work on it.

I think you're chasing your tail. The water pump doesn't generate the pressure under the radiator cap -- that pressure is generated by the expansion of the fluid in the cooling system as it heats up. And, there's really nothing that could be the matter with the water pump that would cause it not to pump adequate coolant through the heater core, given that you've already told us one of your heater hoses is getting hot (indicating ample coolant flow through it). It's best to diagnose properly, according to info you've, erm, been amply given in this thread, rather than just guess and throw parts at it.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

My 68 Dart has the same issue... not getting warm enough in very cold weather (it was 10 degrees outside the other afternoon, and I don't think I could get the cabin above 60).

Of course, the same symptom may not be from the same problem.

I think I have traced my problem to an airleak around the fresh-air doors, (the ones by your feet) especially near the hinges. I was able to feel quite a draft coming out from around the edge of that door frame as I drove down the highway.

I'll seal this leak tomorrow and let you know if it helps.

-Mac

Which begs the question... what is the car you are having the problem with?
(Maybe I missed that detail somewhere along the way)

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

Thanks for all the tips guys.

Dan, I wasnt ignoring the suggestions, I was just taking advantage of the situation where I could take my car in and have it worked on for free. Basically what they did is instead of running both lines from the water pump to the heater core, they took the line on the right and routed it to the head and then brought the line off the head to the heater core. Now im getting sufficient coolant to the heater and for the first time since ive had the car, I now have heat!

"Both lines from the heater to the water pump" makes me go "YIKES!".

The inboard fitting on the water pump is supposed to be connected to the bottom fitting at the front of the cylinder head. If it isn't...make it so!

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

You're exactly right and thats how its all connected now. I knew it looked funny but I couldnt remember how the setup was before my car went into the shop. Now everything is working perfectly fine and both hoses are nice and warm all the time. Thanks for the help.