S4amoht4

So, it's turning cold and the first time I tried my heater out on my recently acquired 4runner, I get nothing but cold air. I replaced the thermostat and thought that might be the quick fix, but still no hot air.

I have a heater core ordered and on the way, is that the best 'next step'? Just a little FYI for you, I found a pile of shiny gold flake looking gunk in my radiator resovoir. Is that stop leak? Could that have something to do with the heat not working?

Any ideas would be much appreciated.

swampfox

try checking the water shut off valve at the fire wall. make sure it is opening. also check and see if the hoses are hot to and from it. that will give an idea if the heater core is plugged. most toyotas have this valve.

S4amoht4

I will look today when I get off work. Would it make sense that this would be in the off position if the heater core was leaking??

swampfox

it could still leak water, if it is plugged and not flow enough to heat as it should. when you remove the heater core be careful not to damage the tubes where the heater hoses hookup. I replaced a core in a 86 model and had to reuse them. It took a lot of work to straiten them back out.

toyospearo

Hey swampfox. I am dealing with a similar issue on my buddies 85 22r. Do you have a picture of were the shut off vavle at the firewall is. Or, could you give me a little detail on where it is? I don't want to tear the heater core out if I don't have to.
Also, if it is plugged can you pull one end of the hose off and run compressed air through it to un plug it??
thanks

S4amoht4

toyospearo, I found this thread after reading your post. I think this is the valve that swampfox is referring to. Thread has a lot of good pics with several different types of valves.

https://www.yotatech.com/forums/f115...n-idle-192717/

RobD

Did you burp your cooling system after changing your T-stat out?

swampfox

I don't have any way to take a photo. On my 89 pickup with a 22r the valve is between the back of valve cover and the master cylinder.It will have a cable going to it. If it is plugged you might try putting radiator cleaner in the heater core, while it is still in place. I seen it done by a toyota tech .it worked allright.

S4amoht4

Well, I called myself burping the cooling system after I changed the t-stat out. I may try it again for good measure. From the threads I have read, the best way is to park on an incline, remove the radiator cap, and turn the heat on wide open, and add coolant as necessary. Is that correct?

Another quick question, where does everyone's temp gauge run? Mine never makes it halfway. It is constantly to the left of center, if it were a fuel gauge, it would be running a 1/4 of a tank.

myyota

If you have the original heater valve on your 4Runner then its probably rusted closed, mine was the same way so i installed one from an 89 4Runner, its a newer style valve and it won`t rust closed. Ive also replaced heater cores on two 86 4Runners and you need to remove the complete dash to do it, and if you have never done it before its about a six hour job. The second one that i did only took four hours because of the experience doing the first one. Its not hard to do, just time consuming.

abecedarian

If the heater core has a leak, it's possible for coolant to flow into the heater core even with the valve closed. It will come up from the return piping when the engine is off and the coolant is warmed up since warm coolant will be under pressure.

S4amoht4

Thanks for the heads up myyota. Just thinking about taking the dash off gives me a headache. I didn't get a chance to check the valve today before the sun went down. Hopefully I can look into that tomorrow.

LITLRED

Replacing the heat exchanger is a big job and I would only do that if your current one tested bad. You can test it for leaks or clogs via the pipes that stick thru the firewall.
When i bought my '86 4runner, the PO had rerouted the hoses to bypass the heat exchanger. I assumed he did that because the core was leaking. Not!! After spending couple days pulling it out I discovered that the valve on the firewall was stuck in the on position. (I did this while my engine was at the machine shop.) I couldn't find an aftermarket valve so I with time and elbow grease was able to free up the old one.

myyota

Like i said before, it looks more intimadating than it is, because you are removing the complete dash. Its just a matter of finding all of the hidden nuts and bolts, after that its easy.

mpavolka

If you want to test the installed heater core, just hook small hoses up to one of the lines coming throught the firewall. Use a funnel and hold it up high fill it with water, lift it up and water should run out of the other line. I know it sounds like that wouldn't be much pressure but thats all a working heater should need. If you use compressed air you risk blowing up the heater core, not a huge problem if it is plugged already, but will leak coolant in your car.

Chances are your heater core does not have a leak because you would most likely see or smell coolant in your car. The heat would probably still work and you would be losing coolant.


S4amoht4 you are correct that the best way to burp the system is to have the front of the vehicle higher to try to get air bubbles in the block and heater to escape and move higher to the radiator.

S4amoht4

I just go an e-mail notification telling me the parts store that I ordered my heater core from is unable to ship it at this time and they gave me a full refund. I think it's a sign. I will check the valve today if the weather breaks. It's raining like a cow pissing on a pine pole bridge right now. If the valve doesn't give me any indication of being faulty, I will try to flush out the heater core.

Does anybody have any pictures of what hoses to unhook and where to unhook them at? Sorry if that's a trivial question. This would be what some would consider a 'first rodeo' for me.

S4amoht4

mpavolka, that's a nice observation. I suppose I should have thought about that earlier...

4Crawler

iTrader: (3)

Easy enough to find the two heater hoses that pass through the firewall as they are the "hoses that run to and from the heater":

http://www.4crawler.com/4x4/CheapTri...ne_Pix/14.html

S4amoht4

Thanks for the reply, 4Crawler. Looks like the setup is a little different on the '85 compared to the '95. I wish I had that much room to work with. ha!

S4amoht4

An update, I was able to check the valve yesterday. It seems to be working correctly. It would open and close as I turned the temperature lever from hot to cold.

However, I did notice that the return line from the heater never warmed up. The in-flow line warmed up nicely as the engine warmed up so, I'm thinking a clogged core may very well be the problem. I'm going this Friday to get some Toyota coolant and a Toyota t-stat for good measure. I just can't trust the napa t-stat after reading through some of the post. I will flush the core and install the new t-stat this weekend.