I've got an 85' Olds custlass 5.0. There is no heat blowing out. New Thermostat, gasket and water inlet valve. The hose from the water pump to the heater core is only hot about 1/4 of the way up the hose. The rest is slightly warm. The return hose from the heat core to the motor is hot. Also the Upper radiator hose is hot, but the lower is slightly warm. The heat was working fine and just stopped. I noticed some leaking around the water inlet valve so I replaced that with a gasket and thermostat. This did not solve the problem. We are coming into winter and need heat.
Also we bypassed the heater core and went directly from water pump to engine and the lines were then getting warm/hot. We blow out the heater core with air and minimal debris came out.
Please help.
@cell4me78
When replacing parts did you get new hoses? I had old hose that separated inside. Would block flow one direction, not the other. New hose fixed it.
Hoses have not been swapped.
Well I’m going to replace the water pump now. Still no heat.
Two 5.0 L engines were used. A Chevrolet and an Oldsmobile.
I would try back flushing the heater core rather than blowing air through it.
Actually, the return hose from the heater core is the one that goes to the water pump. The heater hose that goes the heater control valve goes to the pipe on the bottom of the heater core an vise versa.
Try removing the heater hose from the water pump and cap the port on the water pump. Pinch off the heater hose that goes to the water pump. With the engine running, unclamp the heater hose. Do you get good flow? If not, you most likely have a plugged heater core. If you get air then good flow, you were air bound.
If air bound, where did the air come from.
Not properly bleeding the cooling system. Try vacuum filling the system.
A leaking head gasket. Do a combustion leak test for a bad head gasket.
@bc-st
Thanks for the help. I will try this and report back.
@bc-st
A neighbor paid for a new A/C compressor because of "no air conditioning". The wire from the dash to the A/C damper position had been disconnected. He had a new compressor and still no cooling. Fixed the damper to allow cold air flow and cooling happened. A simple disconnect between the dash controls and the conditioned air fixed the problem. This problem seems to be about heat distribution than heat production.
So the cable from the heater A/C control to the blend door was disconnected. Glad you found it and it's fixed.
@bc-st
@jimz
The cable for my blend door is operating fine. I took the heater core/ac coil cover off last night. Heater core not clogged. The blend door moves when it should. Did notice slight corrosion on bottom of core which would has been there for awhile. However it’s right where the drain hole is inside the box/housing. Going to replace heater core since it’s fairly cheap. Still need to properly test pump as not 100% sure it’s distributing coolant properly. Otherwise it’s probably the intake manifold leaking, I guess.
Did you try swapping hoses at core?
@jimz
We did remove the heater core all together and directly connected to the engine from the pump and the lines would get warm/hot.
@jimz
I have 1 long hose from water pump that's actually longer than needed, which might be standard. The hose will get hot 1/4 of the way from the pump, the remaining 3/4 of the way are not warm at all. The return from the core to engine is Hot. When we took the core out of the equation, it was also warm/hot.
Odd part is the upper hose on radiator is hot, but the return hose is warm at best.
I had a heater hose that was separating inside. The inside would act like a check valve and stop the flow of water. I added new hoses to fix problem.
Check the heater temperature blend door.
@mountainmanjoe
It’s working as it should. Ac has never worked since we got it.
Heater core. Not clogged. Can you add pictures?
Replaced heater core and did not fix. Ugh
Does the water pump pull through heater core from engine or push it through from water pump to core to engine?