95 GMC Sierra k1500 sle

[BigCountry434]

I know this might be a bit weird and crazy, but can someone point me in the right direction. I’m trying to figure out which heater core hose go where preferably the outlet hose when I got the truck it was running to the water pump and not the radiator so I’m curious if running it to the water pump is correct or not I’ve searched the internet to no avail. If someone could nudge me in the right direction I would appreciate it.

 

[Schurkey]

Coolant flows from right rear of intake manifold to heater core, from heater core to either the radiator or the water pump inlet.

The heater core outlet hose diameter is often larger than the inlet hose, but not always.

Are you having some problem with the heater?

 

[BigCountry434]

Thanks for the quick response. Yeah I am. I’ve replace water pump blend door actuators heater core thermostat. Pretty much when I leave the hose hooked to the water pump I can’t see any circulation in the radiator but if I hooked it to the radiator I can see it flowing from the heater core as soon as I start the truck on a cold start. The truck heats up to maybe Luke warm if that.

 

[Schurkey]

I’ve replace water pump blend door actuators heater core thermostat.

Commas would make that more readable.

Pretty much when I leave the hose hooked to the water pump I can’t see any circulation in the radiator but if I hooked it to the radiator I can see it flowing from the heater core as soon as I start the truck on a cold start.

Absolutely normal. Without a heater hose going directly to the radiator, the thermostat will block flow when the engine is cold. If the hose does go to the radiator, there'll be coolant flow from the heater core in the "cool" tank even with the thermostat closed.

The truck heats up to maybe Luke warm if that.

The engine, or the cab?

Verify engine temperature using a scan tool to read the coolant sensor; or drop a thermometer probe into the radiator fill neck.

If the problem is the cab not warming up, verify that the air doors work like they're supposed to, and that the crappy foam gaskets that seal the ductwork--ESPECIALLY the one between the steel cowl and the plastic inlet for the HVAC fan are still intact. My foam gaskets turned to jelly, the cold air POURED into the cab from under the dash. So even with the heater/AC working properly, the cab was cold in the winter, and of course hot in the summer.

 

[BigCountry434]

Thanks! I’ll look into it and see what happens. Will be in touch with findings.

 

[BigCountry434]

@Schurkey sorry for late response work has been busy as hell. But I’ve done all of what you said checked over everything now I’m getting heat hot heat as long as I’m setting but no soon as I take it up the road or drive it to work I the heat cools down. Temperature hand will go to 210 and come back down. Could this be a bad radiator? Thermostat is new.

 

[Donald Mitchell]

You might need to pull the blower motor and clean out the dirt and junk on the evaporator core. That's where the air comes in form outside. You will be surprised at what you find.

You must be registered for see images attach

 

[Schurkey]

I’m getting heat hot heat as long as I’m setting but no soon as I take it up the road or drive it to work I the heat cools down. Temperature hand will go to 210 and come back down. Could this be a bad radiator? Thermostat is new.

Does the coolant level drop? Ever have to add coolant?

Makes me wonder if you have a failed head gasket or cracked casting--pumping combustion gasses into the cooling system above idle.

USUALLY the issue is poor heat at idle, gets better with RPM. You're having the opposite problem.

 

[BigCountry434]

It was dropping at first, but that was also after I done the flush on it after getting all the air out of the system it wouldn’t drop. I’m thinking hair line crack some where because it’s also dumping coolant back into the reservoir instead of going in the radiator.

 

[BigCountry434]

You might need to pull the blower motor and clean out the dirt and junk on the evaporator core. That's where the air comes in form outside. You will be surprised at what you find.

You must be registered for see images attach

Will also give that a shot.