wyoming9

iTrader: (1)

Just like a radiator it is possible to have a good flow through the heater core with a lot of tubes blocked so the flow just carries the heat back into the engine instead of dumping it into the heater core and into the vehicle.

Unless the valve on the firewall is broke and the cable opening and closing it does nothing:jessica:

lobukbuild

there was an old trick that they used to do at the dealer to correct this, simply reverse the flow of the heater core by swapping the hoses,itll take a few days to get results. sounds stupid but it works. i swap my hoses now every year. another important issue with toyota cores is that they do not like a coolant mix higher than 50/50.if there is any dought about the valve on the fire wall, a good test is to just bypass it. you can also try a new radiator cap (or try the one from the camry) to test it. hope this helps.

iliketoyota

i was wondering about that...if it could just go in one tube and out the other without passing though the fins. I may just need a core after all. I would like to make sure that is the problem first though.

and yes the control is defiantly working...i have watched the heater valve move and i can hear the flap slapping open and shut when i move the temp control. It definatly makes a difference when you move the adjustment control around.

iliketoyota

i have actually switched them back and forth twice for about a week. And could a radiator cap cause problems like this?

TNRabbit

This is good advice.

It's not the radiator, radiator cap, or water pump. Everything you've stated sounds like your cooling system is working fine.

Have you used any leak sealant in the cooling system at any time? This stuff with eff up EVERYTHING in it's path. My guess is that it was used at some point & blocked up your heater core. Replace it.

j2the-e

Did you bleed the cooling system using the method I suggested? 22r can be a real pita to bleed because the upper hose acts like a p trap

iliketoyota

Not yet my dad has a no spill funnel at work and i need to go get it.

iliketoyota

No I never used it. When I flushed the core with CLR all that came out were little black and brown looking flakes if that means anything.

lobukbuild

radiator cap pressure helps control flow in the entire cooling system. the heater part of system is the most restrictive part of the system. a weak cap could cause propper engine temps but low heat out put. this might not be your problem but worth looking at.

Mudcat

I just went through this with my 88 4Runner. I was not getting very much air and it was not that warm. I removed the AC condenser and found this.

I took the condenser out of the box and flushed it with water both directions for several minutes. Finally got to where I could see light through the fins.


You have to be careful to not bend the fins though I just used regular water hose with no nozzle on the end. I now get hot heat and enough air to blow my hat off. My AC was not charged up so no big deal. It is easy to remove and only took a couple hours from start to finish. I will fix the AC when it gets to be 100 degrees again.

Richard

how doea the A/C condesor affect the heater ?

j2the-e

Wow thats a lot of dirt!
Richard- Air always flows through the A/C condensor, even on heat setting. The blend door routes more or less air through the heater core- after the condensor

iliketoyota

The air is blowing strong out of the vents though. So would that rule out that problem for me?

iliketoyota

Today I drained the cooling system, refiled it with new 50/50 mix and bled it with a no spill funnel. I also switched the heater hoses around again. Its still exactly the same. I'm probably just going to buy a core unless you guys can think of anything else. Also where is the cheapest place to get heater cores for a 4runner with no rear heat. Cheapest I've found is $80 on rock auto.

iliketoyota

well i put a new heater core in...and guess what....still not much heat, same as before.

The motor never overheats but you can drive it for half an hour and the lower radiator hose is still about 55 degrees on a 20 degree day (tested with one of those red dot infrared or whatever temp guns) its should be hotter than that right? Both heater hoses are always the same temperature but sometimes they are just warm not hot. So im going to take the water pump off in the next couple days. It really sounds like its bad but it never gets hot so im not sure. That same temp gun said 180F at the thermostat housing so i know its getting up to temp and the thermostat is good.

iliketoyota

im getting plenty of air its just not very hot. And i just had the dash apart and i looked at the condenser to see if it was plugged, and it was fine.

iliketoyota

btw all controls and flaps in the dash including the heater valve are working fine. I just had that all apart and all cables and flap linkages are good and moving fine.

jerry507

At this point I can't come up with anything more than "You have bad flow to the heater core".

vikkz

i read this entire thread and i was hoping it was just your heater core. Im wondering if there is something blocking your heater hose somewhere keeping the coolant from running through the heater core.

Is there a way that you can take the heater hoses off and turn on your truck and the heater on full blast just to see if coolant is coming out of them. I never done this but after changing the heater core it probably wouldnt hurt to try that to see if there is any coolant going through those hoses.

iliketoyota

That's what I'm going to do. Then im going to take the water pump off either way.