the_supernerd

I was wondering if anyone here has ever replaced their heater core in an 84-88 4x4 truck. My heater is not as hot as it used to be and I was thinking of replacing the core. Is it very difficult? I can fix things on my truck, but I am not an expert mechanic and I do not want to start and not be able to finish the job or take the chance of messing up something else.

the_supernerd

I am pretty sure it needs to be replaced, although it is not leaking. The hoses seem to be fine and I have already replaced the control valve. I also flushed the cooling system and changed the antifreeze. I do not want to use that flushing stuff because I heard that it could break down some thick corrosion which would create a small hole for it to leak. I replaced the thermostat a while back and it did no difference to the heater. Thanks for the suggestions.

Yoda

I have gotten the heater to work better by undoing the heater hoses, and using the garden hose to push water through the core one way, then the other. Alternate it several times. Sometimes you can see the crap come out of it. If water seems to flow very slow through the core it is probably plugged and needs to be changed. It is not too difficult IF you dont have AC.

Hrdrd

On the heater core thread...my core works fine, fan too, except i have to manually open and close the valve spring and fall. My problem is i think the fan isn't blowing through because of debris. Can i blow this out without removing the dash?

j2the-e

Does it blow properly when you switch it to cold?

Hrdrd

The fan blows cold with the switch that way and just a little warmer switched the other way. I guess core is fine but air is somehow restricted enough that it is blowing everywhere but through the core. Make sense?
I just hate the idea of pulling the dash, but winter is upon us, and this is my "winrter porsche"

j2the-e

Not likely. I would check the cable to the blend door, and I would bleed the cooling system. Take the radiator cap off and run the engine at 1500-2000 rpm with the heater on full blast.

Hrdrd

I just cleaned out the core, both directions with pressure hose. The hoses are hot on both sides of the switch. The switch is broken off in the dash, but i do it manually. I will try that rad cap off thing though to see if that works.
I suppose to fix the slider that controls the mix, I'll have to take the dash out. but looking at the step by step, and with a flat rate of 8 hrs, I'm leery.

the_supernerd

On my '87, I can access the blend door lever on the box without removing anything. Just to replace the cable could probably be done by just removing the radio bezel and the heater control levers. Another issue could be the thermostat. If the engine takes a long time to warm up, then that could be the problem. To address your original question, you can probably take out the duct under the glove box between the fan and the heater box, then vacuum out most of the debris with a shop vac.

I replaced my heater core after posting this thread years ago, and it seemed to work well. Recently, my truck has been having head gasket problems and I noticed that the heater does not work as well as it used to. I think it is allowing air into the cooling system that creates bubbles in the heater core. Hopefully that is not your problem, but it is worth checking before replacing the heater core.

Hrdrd

Thanks for the. Help guys. It was a vapour lock. Bled with rad cap off

TJC

I have a 99 Tacoma I need to replace the heater core. Do I need to remove the AC cooling unit or will it come out with the AC system still intact?

Basnbuks

On my 96 i had to remove the ac unit... Alot of crap had to come out bt its doable. Heres a pic to give u an idea

TJC

Yeah it looks like a hassle I'm going to start on Sunday. I had my AC system evacuated.

Were you able to leave your steering collumn intact? it looks like you were.

Basnbuks

Seems like i had to remove a bracket or something but didnt have to remove it. Label ur bolts it u can, i had 3 left over lol. Suprisingly tho the dash dont rattle. I went into it blind, took me 1/2 day to get core out and couple hours goin back together.