Heater Core Hoses and Heating Issues

[AJ 3]

On my new purchased 1979 stepside with a 350 engine I am having an issue with interior heat. Everything works electrically but my VW's seems to blow out hotter heater air than my truck. I have replaced the thermostat with a known working one (I tested it first).

After looking over the heater core hoses they start at the intake manifold. Then run to the heater core and back to the radiator. After looking at my 2003 4.3 Blazer and 1993 305 truck. Both return from the heater core and run to the water pump.

On my 1979 truck I have a plug at my water pump that I could unscrew and run my heater core return there like my other Chevy's. So which way is correct, return to radiator or return to water pump?

Could this quick fix solve my heating issues or do I totally have other issues. Like a plugged heater core or a not working cable somewhere.

 

[austinado16]

I don't recommend installing used T-stats. A nice new Mr. Gasket T-stat (top of the line) is dirt cheap. Just because a T-stat tests ok in a pan of water doesn't mean it'll last, be accurate, flow properly, blah, blah, blah.

Regarding the heater, remove the hoses from the core. Foreward flush and backward flush the heater core. Do similarly with the hoses to the engine.

 

[chengny]

Deja vu! Another member asked a very similar question yesterday.

Flow through the core is in from the bottom, up through the coils and out the top.

The bottom hose is the higher pressure hose and connects to the nipple on the intake manifold.

The return to the engine is from the top of the core and can connect to either the tapped connection on the water pump or the nipple on the top of the RH side of the radiator. Schematically speaking, in the system the are in the same run of pipe.


See this link for more information/images

http://www.gmsquarebody.com/forum/showthread.php?t=8877

 

[Slick51]

Maybe too late to be helpful here, but I just fixed a similar problem with my 1985 c10 with a later model 350. My ducting worked fine and the air blew out of the correct holes, but it never got hot. My problem ended up being that there were 2 ports out of the water pump that I could connect the heater hose to, one to the passenger side (right) and the other to the driver side (left). I had it hooked to the right side of the pump which turned out to be more on the suction side of the impeller. I switch the lines in wammo! Warm air out of the heater. Hope this helps!

 

[GreaseDog]

I don't recommend installing used T-stats. A nice new Mr. Gasket T-stat (top of the line) is dirt cheap. Just because a T-stat tests ok in a pan of water doesn't mean it'll last, be accurate, flow properly, blah, blah, blah.

I'm not sure I'd qualify anything with a Mr Gasket logo on it as "top of the line". Stant is the name you want to look for in thermostats.

 

[MrMarty51]

Stant is good stuff.
Forwards flush heater core, then reverse, then, blow through with compressed air, very carefully until all the water and sludge is pushed out, then open the air a bit more, reflush, blow, and flush and blow through until water becomes clear.
Intake manifold is pressure side. Also, hook pressure side to lower on the heater core, hot water rises and helps the flow.