I have an 88 pickup 22re 4x4, the issue is I have no heat, these are the things I've done: I have changed The thermostat, I have changed the water pump, I have burped the system at an incline. I have confirmed the heater core is free flowing by flushing the heater core with garden hose, I have confirmed hot water is actually entering the heater core by taking the inlet hose off at operating temperature the water came out hot, I also took the return hose off at operating temp and the return water is hot. I have confirmed that the heater valve is open on inlet hose, I have confirmed that the blender door is functioning properly, the only thing I haven't done is replace the heater core. But I wouldn't think it's bad if it is free flowing or am I wrong?.

 

One thing I have found is if the coolant level is to low the first thing is no heat.

If this is not your issue look to see if the old heater hoses are just sucking closed?? Have they been replaced??

Have you pulled the heater box apart could be the heater core is just blocked by years of dirt.

 

Same problem. For 7 years now, I just decided to care. Subscribed!

 

I've stayed on top of the coolant level, also like I said I let the engine get up to operating temp then pulled both the inlet hose and return hose loose to confirm hot water going in and water coming out from the return side. When I did the heater core flush it flowed from both inlets freely and did not seem to be any blockage,

 

As wyoming9 mentioned above, the external fins on your heater core are likely plugged with dirt and grime so the coolant inside the core is not making good contact with the air from the heating system i.e. the grime is acting like an insulator.

 

No blockage inside but 27 years or so of dirt on the outside of the heater core.

Unless your Truck lived in a NASA lab most of it`s life.In the super clean environment .

I have to clean the mice nests out every few years.

 

I took the heater core out today and it was definitely the culprit, very clean on the outside but it did have blockage on the inside pretty bad with rusty goodness I'm guessing when i flushed it the water was just flowing over the blockage and right back out the return, thanks for the input guys, new heater core will be here tomorrow.

 

Since you have the core out, now is a good time to clean the blower motor box and the AC Condenser too. With the blower box out, there is a stove pipe that extends up into the cowl just in front of the windshield. You can remove the cowl and get a lot of debris out of the cowl and keep it from getting into the ventilation system again. I would suggest putting a screen mesh over the openings to help cut down debris getting in it again.

 

Hi guys, Reelal here, just somethimg to keep in mind if anyone else has a heat problem. Have seen the heat valve lever, under the hood, rust loose from the cylinder inside so it doesn't turn consequently no heat.